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DECEMBER, 1967 THE ANALYST Industrial Gas Analysis Vol. 92, No. I101 A Literature Review* BY (THE LATE) H. N, WILSON AND G. M. S. DUFF (Imperial Chemical Industries Ltd., Agricultural Division, P.O. Box No. 6, Billingham, Co. Durham) SUMMAEY OF CONTENTS Introduction Permanent and inorganic gases Analysis of liquefied or pure gases Fuel gases Flue gases Motor exhaust gases Analysis of micro samples Atmospheric pollutants IN this review we have covered the years from 1958 to about mid-1966, because a chapter on gas analysis by A. E. Heron and H. N. Wilson in Volume 1A of “Comprehensive Analytical Chemistry” (Elsevier Publishing Co. Ltd., Amsterdam and London, 1959, pp. 236 to 327) gives a survey of developments up to 1958. We have not attempted to list every paper, but have tried to present a reasonably comprehensive review of the present methods of gas analysis.We have omitted many papers that roused our scepticism rather than approval and have commented on some of the papers to which we have referred. In no branch of analysis is the swing towards physical methods more marked than in gas analysis. There have been no important developments of the conventional methods during the last 10 years; the chief advances have been the application of galvanic methods to “traces” of certain gases, and gas chromatography. Indeed, although such apparatus as Orsat’s, Haldane’s and Bone and Wheeler’s still have their place, in some industries they are obsolete and in others obsolescent. Dr. E. A. C. Chamberlain, Divisional Chief Scientist, National Coal Board, Scottish Division, informs us that in the analysis of mine air the gas chromatograph is now the apparatus usually used, and that in a survey of the atmosphere in one pit, as many as 17,000 samples have been analysed over a period of 12 weeks by this method.The rapid spread of the electrogalvanic methods for the “on-stream’’ determination of traces is also most significant. The other most noticeable feature is the vast and increasing attention being paid to atmospheric pollutants of all kinds, particularly sulphur dioxide, sulphuric acid and hydrocarbons. PERMASENT ANT) ISORGANIC GASES GENERAL- - There have been few papers dealing with the older methods of gas analysis; these methods had all been developed to such an extent that major improvements were becoming rare; usually if quicker or more precise analyses are required, it is necessary to have recourse to a physical or instrumental method.There are a few papers to record that deal with Orsat’s apparatus. Charpenatl measures all gas volumes over mercury at constant pressure and, as a further departure from the usual method of working, dries the gas before and after each absorption. The minimum volume of de-gassed reagent solution is sprayed on to the walls of the absorp- tion tubes; explosion with oxygen is retained, but the eudiometer is made of stainless steel. The apparatus is recommended for checking the purity of such gases as carbon dioxide from cylinders, and high accuracy is claimed, but there seems to be no reason why this apparatus should be more accurate than a well designed constant-volume apparatus.* Reprints of this paper will be available shortly. For details see Summaries in advertisement pages. 723724 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS [A;~zaZyst, Vol. 92 Blakemore2 combines the Orsat with a gas-chromatographic apparatus on JanAk’s system3; this apparatus is intended for analysing town gas made from, or enriched with, petroleum hydrocarbons. Three components, carbon dioxide, oxygen and, if desired, un- saturated hydrocarbons are successively removed by absorption and the residual gases passed on to the gas-chromatographic part of the apparatus. An activated-carbon column separates the permanent gases, and either alumina or diethyldigol is used to separate the hydrocarbons. Blakemore prefers the JanAk system to the more usual detectors as he considers it more suitable for operation by junior staff, but this opinion is no longer held in many laboratories.Barnard and Hughes4 describe modifications of absorption methods for determining carbon monoxide, oxygen and methane. Bracht5 compares the precision of modified Orsat apparatus between operators and between laboratories, and makes a comparison with gas- chromatographic apparatus. Schoedler6 compares the Orsat analysis of furnace gases with a 2-column chromatographic technique, and Ebersbach7 reviews Orsat reagents. Lloyda describes a modification of Haldane’s apparatus, perhaps the most important modification being a multi-channel tap,g and GooderhamlO describes modifications to the constant-volume apparatus, for which Chapman and Murchell have designed an absorption pipette with a magnetic shaker. Schwab and Neuwirth12 describe a continuous gas analyser in which the flow of gas (corrected for viscosity effects) through a series of absorbers, connected by capillary flow- meters, is recorded.Kienitz13 reviews classical and modern methods, including chromatography and infrared analysis of organic and inorganic gases, giving 33 references; modern methods of gas analysis are reviewed by Kainz14 and physical methods by Guerin.15 Non-dispersive infrared gas analysers (“Luft” gas analysers) are described in a detailed review,16 and a versatile tran- sistorised double-beam infrared gas analyser, suitable for use in a potentially explosive atmosphere, is described by Hill and Stone.17 An infrared analyser in which the radiation source is a heated cavity containing the component in question is described by Sall and Stanevich .I8 Mass-spectrographic methods are dealt with by van Katwij k,l9 and Carnides,2* who deals with gases with identical mass numbers.McLaff erty21 reviews applications of mass spectro- scopy to production, e.g., argon in ammonia plant gases, while another paper on the application of mass spectroscopy deals with the analysis of the rare gases in works control.22 Permanent gases, free from corrosive components, can be analysed with a coefficient of variation of 5 per cent. at the 1 per cent. level. This is particularly suitable for mixtures containing hydrogen, helium, oxygen, argon, carbon monoxide and carbon dioxide.23 A U.S.Atomic Energy Report24 describes modifications to a single-focusing mass spectrometer to enable it to be used for the analysis of mixtures of carbon monoxide and nitrogen. I ~ u d e r ~ ~ measures the oxygen-18 abundance in determining oxygen in carbon monoxide - carbon dioxide mixtures. The omegatron is discussed by Wagener and March.26 McGrath, Magee, Pickering and Wilson27 give a theoretical and experimental discussion and a literature review of analysis by molecular-emission spectroscopy, especially of the methods of excitation of permanent gases ; application to hydrocarbon gases is probably not feasible. Electronic molecular spectra, particularly of organic compounds, are also reviewed by McGrath, Pickering, Magee and IVilson.28 Despite the lack of specificity for given wave- lengths and rather difficult conhtions, the high sensitivity of the method may lead to its being used for very small samples; the spectra of nitrogen, hydrogen and ammonia are, as yet, affected too much by i m p ~ r i t i e s .~ ~ High frequency discharge is applied by Botschkowa, Frisch and Schreider30 to the determination of impurities in the inert gases, and of krypton in oxygen, and Stolov31 used this method to analyse mixtures of nitrogen and carbon dioxide (1.5 to 33 per cent.). The whole field of spectroscopic analysis of gas mixtures is covered in a recently published text.32 The use of gas chromatography in the analysis of permanent gases is rapidly increasing and the subject has been comprehensively dealt with by Jeffery and K i ~ p i n g ~ ~ in a book that covers the whole field of gas chromatography, as applied to the analysis of gas mixtures.The replacement of the Orsat by gas chromatography has been comparatively slow, partly because no single chromatographic column has been discovered that is capable of separating all of the components determined by this apparatus. The development of molecular sieves solved the problem of the separation of hydrogen, nitrogen, carbon monoxide andDecember, 19671 WILSOh' AND DUFF: INDUSTRIAL GAS ANALYSIS 725 methane, but carbon dioxide requires separate treatment and the separation of argon and oxygen requires special conditions.34 to 45 The use of argon as carrier gas simplifies the deter- mination of oxygen, and careful design of columns and flow-circuits enables the remainder of the above gases to be determined on a single apparatus.46 The results obtained with such a system have been compared with those obtained by using a Bone and Wheeler apparat~s,~' with satisfactory agreement.The conditioning and preparation of molecular sieve columns have been described by JanAk48 and Farr6-Ruis and G ~ i c h o n , ~ ~ among others, the latter authors contriving to separate hydrogen, oxygen, nitrogen, methane and carbon monoxide in the extremely short time of 15 seconds. I t has been shown that the life of a molecular sieve column is vastly increased if both samples and carrier gas are rigorously dried.50 The problems of precise quantitative measurement have been discussed by Vizard and W ~ n n e , ~ l and by K i ~ p i n g , ~ ~ who describe zero-suppression circuits that are necessary for the accurate direct determination of major components in a mixture.The use of a cross-section ionisation detector for permanent gases is claimed to have the advantages of sensitivity and wide linear range,53,54 but despite this it has not been applied widely, as yet, and some of the claims have been disputed.55 The instrumentation of the JanBk method of measurement to give a digital print-out has been described by Kateman and R i j k ~ . ~ ~ Lacy, Woolmington and Hill57 and describe the application of gas chromatography to the gases used in the industrial synthesis of ammonia, while Cerrone, Piatti and Rio describe a multi-column system for the products from the steam-cracking of hydrocarbon^.^^ They separate carbon dioxide, nitrous oxide and oxygen over 20 per cent.dimethyl sulphoxide at 20" C, and ether and fluothane on a column of 15 per cent. dimethyl phthalate at 70" C parallel with the first column, hydrogen being used as carrier gas ; the time taken for an analysis is 4 to 5 minutes. Some interest is being displayed in sonic gas analysers. MartinG1 discusses the principles involved, and, with Mourfield, has issued several patents.62 The instrument is made by Howard Grubb Parson Ltd., and its practical advantages and disadvantages are discussed by H a ~ w e l l . ~ ~ S t o t P discusses a continuous sonic analyser for carbon dioxide in expired air, covering the range 0 to 10 per cent. TRACE ASALYSIS- General-This section is restricted to the determination of trace constituents in gases other than air (liquefied gases have been excluded, the determination of trace constituents in these being referred to later).The most important general technique is the ubiquitous gas chromatography. Extremely sensitive detectors have been developed for organic molecules, which have made the deter- mination of amounts down to parts per million, or even per hundred million, no longer a problem. The various types of ionisation detector suitable for this application have been reviewed by Lovelocks5 ; unfortunately, these detectors do not respond readily to the inorganic and permanent gases, and no simple universal technique has been evolved. Probably the best detector so far is the radioactive ionisation detector, with helium as carrier gas, that has been developed by The metastable helium ions formed on irradiation are used in this detector to ionise the components being determined; this calls for intensive purification o f the carrier gas as well as exclusion of air.Rules for optimisation of the responses are given by Bothe and LeonliardtG7 and a system for purification of helium by Rourke, Grey and D e n t o ~ i . ~ ~ Limits of dctcction are given by Paris11 and Parsons.69 Il'ith a 5-ml sample they could detect 10 p.p.m. o f hydrogen, 0.5 p.p.m. of oxygen, 2 p.p.m. of nitrogen, 5 p.p.m. of carbon monoxide and 0.5 p.p.m. of carbon dioxide. More recently a variant with very low internal volume has been discussed with limits of detection claimed to range from 1 to 20 ~ .p . n ~ . , ~ O and another design has been used in vacuum fusion.71 Several workers have used impure helium and observed the diminution in the standing current when other permanent gases are but these methods have not the sensitivity nor the stability of Berry's system. Previously, several workers had tried sensitising the original argon detector by adding an organic vapour, but this method appears to have fallen into disuse.75 Probably the simplest method, when rapid analysis is not required, is to use standard gas- chromatographic techniques after a concentration stage in which a cold absorption column is ~sed.7~9'~ This technique enables the average laboratory instrument to be extended into the p.p.m. range and further examples are given under the headings of specific gases.Several Adlard and HilPO describe the analysis of anaesthetic gases.726 WILSON AND DUFF: INDUSTRIAL GL4S AKALYSIS [Analyst, Vol. 92 workers have modified mass-spectrometer design to cover the p.p.m. range, in which it is extremely valuable for the determination of the permanent and noble gases in small amounts or when at high vacuum. Modifications to a commercial model to extend the ramge to detect 1 p.p.m. of helium in nitrogen or hydrogen in argon have been described by Parkinson and Toft,78 while an instrument capable of working in the range 5 x torr has also been de~cribed.'~ A procedure for the determination of helium at the p.p.m. level has been des- cribed.80 The production of condensation nuclei by suitable reactions followed by electronic counting has been applied to ammonia, carbon dioxide, sulphur dioxide and mercury, and developed into a commercial apparatus.8l ,82 Argon-The separation of argon from oxygen by gas chromatography is extremely difficult and no completely reliable method has yet been developed.The use of a column of firebrick impregnated with bull's blood has been reporteds3; this must be the only recent use of this reagent, and it has obvious disadvantages. The separation on molecular sieve 5A generally requires operation at inconveniently low temperatures, e.g., - 72" C,34 -78" C35936 and -50" C,37 with long columns that result in broad, ill defined peaks. Better results have been achieved recently, giving separation at -9" C,38 and several authors have claimed separation at rooin temperature, with molecular sieve 5A that had been activated at 350" C in ~ a c u o , ~ ~ in helium,40 at 400" C in purified helium41 and at 450" C in argon containing 100 p.p.m.of water.42 Other workers have resorted to removal of the oxygen by catalytic hydrogenation to water. In such a system43 the argon and oxygen are first measured together and then the argon alone after removal of the oxygen, while in another method the oxygen is measured as a water peak after separation on a column of Triton X305,44 or as acetylene after reaction of the water with calcium carbide.45 If the determination of oxygen is not required, then it is possible to carry out a simple determination of argon by using oxygen as carrier gas.84 Argon in ammonia synthesis gas can be determined by transferring the residual gas from an Orsat apparatus to an interfer~meter,~~ and Hoffman and Helles6 determine argon in synthesis gas by absorption of soft X-rays.Chakrabati, Magee and Wilson8' determine argon when mixed with carbon dioxide (9 to 10 per cent. of argon) by high frequency excitation at 230 Mc/s, measuring the emission with a quartz prism spectrophotometer (a determination takes about 1 minute). Carbon dioxide-There is little new work to report on the determination of carbon dioxide. Earnshawss reviews methods for its determination, and Kiff and Partridges9 describe an indicator-tube method for the range 10 to 50 per cent., in which the reagent is sand- impregnated with rosaniline hydrochloride decolorised with hydrazine ; Bunker, Bendixen and Murphygo measure the change in pressure of a 45-ml sample on removing carbon dioxide with soda lime (for the determination of carbon dioxide in anaesthetic gases a commercial apparatus is available in the U.S.A.).The best method for routine laboratory determination of traces of carbon dioxide depends upon measurement of the change in conductivity when the gas is absorbed in a suitable reagent. In a typical apparatus a spiral absorber is used to obtain the necessary contact for efficient absorption of carbon dioxide.91 ,92 A particularlv neat conductivity cell has been described by Piringerg3 and a recording instrument by Dij kstra94 Other designs have been described by S ~ e k i e l d a , ~ ~ Ehrenburgg6 and P r i ~ c o t t , ~ ~ and the last of these also measures carbon dioxide. Violanteg8 claims increased linearity by saturating his barium hydroxide reagent with barium carbonate to ensure precipitation of all of the absorbed carbon dioxide as carbonate, while Bartscherg9 has published conductivity graphs and coefficients of absorption for a sodium hydroxide reagent containing 2-aminoethanol. There are several titration methods; one based on barium hydroxide involves the use of barium chloride and ethanol to suppress hydrolysis of carbonate,loO another involves the use of a semi-automatic titration to overcome interference by atmospheric carbon dioxide.lol In a method in which sodium hydroxide is used as reagent, butanol and ethanol are added to suppress hydrolysis,lo2 and in another method, in which the same reagent is used, a spectro- photometric end-point detection is described.lo3 Methods in which non-aqueous media are used have been described by Grant, Hunter and Massielo4 (dimethylformamide and thymol- phthalein; titrated with potassium methoxide) and by Patchorniklo5 (benzylamine and thymol blue; titrated with sodium methoxide).It is difficult to see the advantage of these methods, although possibly they give a more definite end-point. A colorimetric method involvingDecember, 19671 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS 727 continuous measurement of the colour of a solution of phenolphthalein in sodium hydroxide has been described by Juranek.lo6 In a most unusual methodlO7 the gas is absorbed in paper saturated with barium hydroxide and held between silver electrodes.After exposure to the gas, a current is passed and the number of coulombs required to decolorise phenolphthalein indicator is a measure of the carbon dioxide absorbed. A particularly sensitive d.c. discharge detector for gas chromatography is claimed to detect 5 x 10-13 mole of carbon dioxide,l08 while a method in which katharometers are used and the sample volume is increased to 94 ml has detected 13 p.p.m.log A method for the preparation of calibration gas mixtures by electrolysis of oxalic acid has been described by Piibyl.llO Carbon monoxide-Stewart and Evanslll prefer a copper( I) sulphate - 2-naphthol reagent for the determination of carbon monoxide with Orsat's apparatus. Moureau, Chovin, Truffert and Lebbe112 describe the preparation of standard mixtures for calibrating an infrared absorption analyser.The oxidation of carbon monoxide to carbon dioxide by iodine pentoxide, followed by gravimetry, conductivity or iodimetry, is well known and is one of the best methods for determining traces of carbon monoxide, and the difficulty occasionally encountered in pre- paring or obtaining a satisfactory reagent is also well known. An alternative reagent, not much used outside the field of microcheniistry, is decomposed silver perrnanganate,ll3 which might have some advantages. An extremely sensitive colorimetric method that is not affected by 100 per cent. of either oxygen or hydrogen involves the reaction of carbon monoxide with the silver salt of 9-sulphamylbenzoic acid.ll4 9 1 1 5 A sensitive method for routine work is by reduction to methane by hydrogen over reduced nickel and determination of the methane by gas chromatography with flame-ionisation detection.l167117 There is no doubt that this method is capable of giving rapid, reproducible measurcmcnts on small samples (about 10 ml) and could be extended below the p.p.m.level. Carbon szibo vide-The gas-chromatographic determination of carbon suboxide, C,O,, and its preparation have been described by Hirt.l18 Helizw-The determination of the rare gases has been described by Gnaukllg and gas- chromatographic methods for helium, neon and krypton are described. Several authors h a ~ e described the determination of helium in natural gas.1201121 T~~~ 7123 The separation of hydrogen and helium is probably best achieved with molecular sieve 5A,124359126 while for extreme sensitivity a preliminary enrichment of the sample by frontal analysis has been suggested.12' Melhuish and Chapman have described the mass-spectrometric determination of helium at the 10-l2 Hydrogen-There are two problems associated with the gas-chromatographic deter- mination of hydrogen.First, with helium as the carrier gas, anomalous katharometer responses are obtained at certain concentration^,^^^^^^^ which necessitate the use of a mixed carrier (92 per cent. of helium and 8 per cent. of hydrogen). Secondly, the high sensitivity obtained with other carriers makes it necessary to apply a back-e.m.f., rather than to attenuate the signal if good precision is to be obtained at concentrations of 40 per cent.of hydrogen131 and above. There is a revival o f interest in diffusion tlirough palladium, especially for very small samples at low pressures. Young and M'hitten132 detect hydrogen down to a partial pressure of lo-' torr by passing the sample over an evacuated palladium thimble at 500" C, the pressure of hydrogen accumulating inside the thimble being measured by a thermocouple gauge or a manometer. A continuous analyser with a palladium - silver alloy has been described.133 Deuterium in hydrogen is measured continuously by thermal cond~ctivity.]~~ An electrolytic method for hydrogen in the range 1 to 1000 p.p.m. has been described by In this method the gas, stripped of carbon dioxide and oxygen, is passed over a platinised platinum electrode partially immersed in a solution of mercury( I) chloride and sodium chloride in hydrochloric acid.The other electrode is a calomel half-cell and the current is proportional to the hydrogen concentration. A method, in which the "Hersch" galvanic oxygen sensor is used to determine the reduction of oxygen consequent upon reaction with hydrogen in the gas stream, is described by Marsh,136 while with another tech- nique the electrolytic hygrometer is utilised to measure the water formed.137 A detector tube for hydrogen in oxygen involves the reduction of ammonium rnolybdate in the presence of palladium sulphate at 100" C.138 As carbon monoxide, hydrogen sulphide, arsine, phos- phine, acetylene and olefins all interfere in some way, it is difficult to see a real use for this tube.728 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS [Analyst, Vol.92 O~ygeiz-Naumann~~~ reviews commercial equipment for concentrations of 5 to 50 per cent. of oxygen. The chief, and spectacular, advance in the determination of oxygen from very low concentrations upwards is the application of the galvanic cell. This has been known in one form or another since about 1913, but recently it has come into extensive use as a recording instrument. Hersch140 gives an extensive account of principles and applications, with 192 references; the ground covered has not been included in this review. He also gives a brief and clear account of the system and an example of its application to traces of hydrogen in a carrier gas, e.g., as evolved from metals on heating,141 besides many contributions to the literature that are mostly concerned with details of instrumentation. Heinmann14* determines up to 99 per cent.of oxygen on a small sample. Oxygen is usually separated from nitrogen by gas chromatography on a molecular sieve 5A, but Rein, Miviele and Fain- berg143 claim to separate nitrogen and oxygen at 30” C by a 50-foot column of 33 per cent. Silicone Oil 200 on Chromosorb Y; retention times for oxygen and nitrogen are 7.3 and 7.6 minutes, respectively, which may be barely adequate in many instances. Reports on chemical methods include the preparation of a modified sodium dithionate absorption reagent .I44 A method for measuring very small differences in oxygen concentration, for example, in air, by determining the differences in pressure on absorption of the oxygen in pyrogallol, the small amount of carbon monoxide evolved being allowed for, has been described by Linder- ~tr0m-Lang.l~~ A chemical detector tube for oxygen, in which manganese( 11) oxide is dispersed on silica gel in an evacuated tube, has been described; on breaking the end of the tube the manganese oxide changes colour and the length of the stain is a measure of the oxygen present.146 Schulek and Pur,g~t’*~ describe the preparation of manganese( 11) oxide froin manganese(I1) carbonate and its use for absorbing oxygen, nitrous oxide and “oxides of nitrogen.” A t 900” C the electrical conductivity of copper(1) oxide varies with the partial pressure of oxygen in the circumambient gas, and this is used to measure the concentration of oxygen.Sulphur or halogen can be measured in a similar way by using copper(1) sulphide or halide. The major recent advance in the determination of traces of oxygen is the development of galvanic analysis by Hersch, referred to above. The general principle is to cause the gas being determined to become a reactant at one of a pair of electrodes and measure the current produced; besides its original application to oxygen, it has also been applied to the deter- mination of hydrogen, halogen, ozone, oxides of nitrogen, carbon monoxide, carbon dioxide, water vapour, “reductants” and methane. Most commercial instruments have been developed for “on-line” operation. A simple cell suitable for laboratory use (and laboratory construction if suitable skills are available) has lead and silver electrodes and potassium hydroxide electrolyte,149 while a modification suitable for use in the presence of carbon dioxide has saturated potassium hydrogen carbonate solution as e1e~trolyte.l~~ A recent development is to use this type of cell as a detector at the exit of a chromatographic c01umn.l~~ A related technique is the use of the wide-bore dropping-mercury electrode after dissolution of the oxygen in water or other suitable reagent,l52although this does not seem to have any advantage for gaseous oxygen.Several colorimetric methods have also been described, some involving the use of anthraquinone-2-sulphonic acid,l53 its sodium salt154 or 9,10-anthra-diol-2-sulphonic acid.lj5 An old technique, in which the colour of coyper(I1) chloride in a solution of copper(1) salt is has been extended by measurement of the copper(l1) ion by electrolytic reduc- iion.l58 Similarly, a continuous coulometric instrument has been developed, in which chromium(I1) chloride is oxidised and subsequently reduced at a mercury cathode; the current is adjusted to maintain a constant chromium( 11) l e ~ e 1 .l ~ ~ Another paper describes the polarographic determination of the chromium( 11) .lG0 A technique, in which an ionisation detector is used to measure negative ions may offer potential development, but does not yet seem to have received much application.161 The quenching of the phosphorescence of trypoflavine by oxygen has been proposed at the p.p.m. Ozone-The determination of ozone in oxygen by thermal conductivity is described by Burlant and Cannon.163 INORGANIC GASES- Gas chromatography is applicable to the separation of mixtures of reactive gases.K ~ n g e l ~ ~ separates carbon monoxide, carbon dioxide, hydrogen chloride, hydrogen cyanide, cyanogen, chlorine, cyanogen chloride, phosgene, nitrosyl chloride and sulphur dioxide on A novel method is that byDecember, 19671 WILSON AND DUFF: IILDUSTRIAL GAS AICALYSIS 729 a column of chlorinated biphenyl or chlorofluorohydrocarbons on PTFE ; similar systems are used by Araki, Kato and A t ~ b e l ~ ~ and Huillet.l(j6 Philips and Gimmsl67 discuss applica- tions of chromatography to the identification and determination of silanes, germanes, silico- germanes and substituted borazoles. The log of the retention time can be used to estimate the number of atoms present in a molecule and the type of chain branching.Substances not previously known have been identified and determined. The separation of the methyl- silanes has been described by Williams and Murray.168 Ammonia-This is determined in gas mixtures by equilibrating with ammonium chloride solution and measuring the pH.l(j9 At high temperature and pressure, ammonia, carbon dioxide and water can be determined by direct infrared spectroscopy.170 Gas-chromatographic methods, in which catalytic decomposition to nitrogen over a hot wire,171 or hyp~bromitel~~ is used, overcome some of the problems of absorption inlierent in the direct method. Boranes-Fristrom, Bennett and Ber1173 determine boron hydride vapours by burning to boric acid, and colorimetric determination with carmine.If hydrogen is present, Putnam and Mye1-9'~ separate the boranes in a cold trap at -78" C and remove the hydrogen in a stream of argon; the boranes are then allowed to vaporise. They determine boranes and chloroboranes by passing them in a stream of argon through a column of molecular sieve moistened with water, the resultant hydrogen being measured. They also separate chloro- boranes, diboranes and hydrogen chloride175 on columns of Teflon, Silicone Oil 703, Fluorolube and liquid paraffin. Relative retention volumes are given for hydrogen, diborane, chlorodi- borane, dichloroborane, boron trichloride and hydrogen chloride. Hill, Kulins, Merril, Palm, Seals and Urqui~al'~ utilise the red colour produced when triphenyltetrazolium chloride, dissol- ved in pyridine, is reduced, to monitor atmospheres for boranes and other reducing agents.ChZorine mid chlorine compounds-A general test for halogen compounds is given by The gas, mixed if necessary with a combustible gas, is passed over heated copper and ignited; a green flame indicates the presence of a halogen compound. S p ~ r n y l ~ ~ determines chlorine by dissolution in carbon tetrachloride and measurement of the optical density at 335 mp; the sensitivity is 1 pg per ml. Neelyls9 analyses cell gas by chromatography on columns of Fluorolube grease on Chromosorb and molecular sieve 13X in series, while a simple chromatographic method for chlorine and hydrogen chloride has been described by Ruthven and Kenney.lso Peruginilsl describes apparatus for the analysis of hydrogen and chlorine mixtures and emphasises that light must be excluded.Spurny182 discusses the photo- metric determination of chlorine and its oxides, giving maxima for light absorption in carbon tetrachloride solution. Dichlorine monoxide and chlorine dioxide are photosensitive and decompose to chlorine and oxygen, while chlorine pentoxide and chlorine hexoxide are stable. Balashev, Kachalov and Rykovals3 give a chemical method for analysis of chlorine and chlorine dioxide mixtures based on reaction with solid sodium chlorate. Reregard and Gliesl-iko~a~~~ describe the cheniical analysis of a mixture of carbon monoxide, carbon dioxide, chlorine, phosgene, hydrogen chloride, oxygen and nitrogen ; zinc and antimony sulphide are used to absorb hydrogen chloride and chlorine, and sodium iodide in acetone solution to absorb phosgene.A mixture of chlorine, nitrogen dioxide and nitrosyl chloride is analyscd by passing the gases through sulyhuric acid. Chlorine is unchanged, nitrosyl chloride con- verted into nitrosvlsulyliuric acid and nitrogen dioxide into nitric acid and nitrosylsulpliuric acid. The sulphuric acid is analysed for nitros>rlsulpliuric acid by permanganate and for total nitrogen by nitrometer; the clilorine is trapped in iodide solution and titrated.ls5 Analysis of mixtures of chlorosilanes by chromatography are described by Kotsche,la6 who uses a column of silicone oil, followed by a column of silica gel to resolve silane and nitrogen, and by Lengyel, Garzo and Szi,kely,lg7 who discuss various solid supports and stationary phases, They favour Celite impregnated with 23 per cent.of nitrobenzene. Fluorine and its com~o~4nds-Horton~~~ reviews trends in the determination of fluorine. Fluorine itself can be determined continuously by reaction with sulphur dioxide, the change in flow-rate being a measure of the fluorine content.lsg Harrison and Reidlgo determine hydrogen fluoride by infrared absorption, passing beams of two wavelengths through the sample, the second beam serving as a measure for correcting errors arising from window corrosion. Smithlgl gives equations for band intensities against partial pressure of hydrogen fluoride when mixed with a foreign gas. Carbon tetrafluoride and hexafluoroethane mixtures can be analysed by reaction with water vapour; at BOO" C only hexafluoroethane reacts; and at 1100" to 1200" C both compounds react.lg2 Thc most common method of analysing730 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS [Analyst, Vol.92 mixtures of fluorinated materials is by gas chromatography. Lysij and Newtonlg3 discuss suitable apparatus and various stationary phases €or the chromatographic separation of highly reactive gases such as chlorine trifluoride, hydrogen fluoride and fluorine; a preparation of halogenated polymers was the most satisfactory column packing. Mixtures that also contain uranium hexafluoride are discussed in two reports by Iveson.lg4 Full details are given of apparatus, carrier gas and stationary phase 1 Kel-F40 polymer oils on Kel-F powder (poly- chlorotrifluoroethylene) 3 for these separations.Iveson and Hamlinlg5 describe the analysis of a mixture of uranium liexafluoride, chlorine, chlorine monofluoride, chlorine trifluoride and hydrogen fluoride by packed column chromatography with katliarometer detection ; a 5 to 15-ml sample is analysed in about 40 minutes. Another U.K.A.E.A. reportlg6 describes apparatus and gives details of a chemical method for analysing a mixture of uranium liexafluoride, fluorine and nitrogen ; standard deviations are given. Nitrogen trifluoride and carbon tetrafluoride are separated by chromatography with a column of silica gel coated with halocarbon oil at 25" C.lg7 Low molecular-weight fluoro- carbons and compounds such as sulphur tetrafluoride, sulphur hexafluoride, thionyl fluoride and disulphur decafluoride are separated on a column of 33 per cent.Kel-F polymer oil on Chromosorb W at 25" C, with helium as carrier gas. The analysis requires recourse to be made to infrared spectrophotometry, as well as the usual chromatographic ~1etector.l~~ Robson and Askewlg9 describe the chromatographic separation of silicon tetrafluoride and thionyl fluoride. Nitrogen compoumds- Jeff ery and Kippingzoo concentrate nitrous oxide, if necessary, (and also carbon dioxide) in mono-ethanolamine, and finally determine it by gas chromato- graphy on a carbon column, while DeGrazio201 prefers columns of silica gel and molecular sieve 13X. Peters202 describes solid absorbents for oxides of nitrogen, such as silver permanganate and sodium chlorite, and Ellis203 recommends a solid potassium permanganate absorbent.Faucett, McRight and Graham204 compared three methods for the determination of the oxidation state of the process gases from a nitric acid plant and concluded that the best method involved absorption in mixed acid, followed by permanganate titration. Leffort205 separates nitrous oxide, nitric oxide and nitrogen on molecular sieve 5A at 80" C, with hydrogen as carrier gas; Sakaida, Rinker, Cuffet and Corcoran206 separate 0.1 to 1.0 per cent. of nitric oxide from nitrogen over a silica-gel column, after an elaborate pre- treatment of drying and conditioning. Morrison207 determines nitrogen dioxide in nitrogen and oxygen (5 to 150 p.p.m.) with an electron-capture detector; see also Soukup.208 Nitrogen dioxide is determined in a continuous recorder by R o ~ t e n b a c h .~ ~ ~ The nitrogen dioxide is absorbed in a bromide solution, releasing bromine, which depolarises the electrodes, and the current is measured. Sulphur dioxide interferes; the range is 0 to 5000 p.p.m. A colori- metric method covering the range 0.005 to 5 per cent. has been described by Norwitz.210 The chromatographic separation of nitrogen dioxide is almost impossible because of its high reactivity, but one author has reported a technique in which a cold trap is used that is packed with glass beads coated with Carbowax.211 Gritzner212 describes the polarographic detection of nitrogen dioxide, nitric oxide, nitrous oxide and dinitrogen trioxide in anhydrous dimethyl sulphoxide. The mass spectrometer is used by Tranchant and Moreau213 for the analysis of mixtures largely consisting of oxides of nitrogen, e.g., gases evolved on burning explosives in a bomb calorimeter.A gas-chromatographic method for similar mixtures has also been described.21g Mixtures containing nitrosyl chloride, chlorine and hydrogen chloride can be analysed by a chemical method after absorption in sodium hydroxide solution.215 Sulphur-containing gases-Fraade216 monitors the conversion of hydrogen sulphide in a Clauss reaction by gas chromatography. The gas-chromatographic determination of sulphur dioxide in the presence of carbon disulphide, carbon oxysulphide, carbon dioxide and the inert gases is described by Brinkmann.217 Novak21s measures sulphur compounds in technical gases by means of a carbon anode (2 to 3 cm2) and a zinc-amalgam cathode (for hydrogen sulphide) or a copper cathode (for sulphur dioxide), immersed in 0.05 to 1 M sulphuric acid solution.The gas is bubbled through the constantly flowing liquid and a continuous record is given for concentrations of 0-01 to 10 per cent. v/v; the sulphur dioxide recorder has run for 2 years without a change of electrodes. Experience with commercial colorimetric instruments for sulphur dioxide and hydrogen sulphide has been described by Clevett .219December, 19671 WILSON AND DUFF: INDUSTRIAL GAS AKALYSIS 731 Adams, Koppe and TuttleZ2O separated hydrogen sulphide, sulphur dioxide, meth- anethiol and permanent gases with Titron 45 and molecular sieve 5A columns in series.Beuerman221 uses a 20-foot column of dinonyl phthalate at 95" C to separate sulphur dioxide from oxygen and carbon dioxide. Robbins222 separates carbon dioxide, hydrogen sulphide, hydrogen, oxygen, nitrogen, methane, carbon monoxide and sulphur dioxide on two columns consisting of 20 feet of 10 per cent. dibutyl sebacate and 7 feet of molecular sieve 13X, while Hodges and M a t ~ o n ~ ~ ~ separate carbon dioxide, carbon oxysulphide, hydrogen sulphide, carbon disulphide and sulphur dioxide on silica gel at 100" C. An oxygen-lamp metliod for determining total sulphur compounds in gases is described by Mason and H ~ m m e l , ~ ~ ~ and a method for determining elemental sulphur in liquefied petroleum gas is described by Gregory,2*5 in which the sulphur is dissolved in pyridine reagent and determined polarographically.Garbalinskii226 determines hydrogen sulphide in the presence of unsaturated hydrocarbons by absorption in copper sulphate solution, and he claims that this does not absorb hydrocarbons as much as cadmium or zinc acetate solutions. Another met hod for hydrogen sulphide involves titration with hydroxymercuribenzoic acid, which, it is claimed, is free from interferences by iodine, sulphite, chloride and thi~cyanate.~~' A complex system for determining hydrogen sulphide, carbon disulphide and carbon oxy- sulphide involves the use of acidic cadmium acetate to trap the hydrogen sulphide and ethanolic potassium hydroxide to collect the carbon disulphide and carbon oxysulphide as xanthates,228 while another system involves the use of aqueous potassium hydroxide to remove hydrogen sulphide and thiols and of ethanolic mono-ethanolamine to remove carbon oxy- ~ u l p h i d e ~ ~ ~ ; the carbon oxysulpliide is determined by titration with silver nitrate, with potentiometric end-point detection.Methods for determining sulphuric acid mist in process-gas streams, with comparisons of impingers, sinters and electrostatic precipitators, have been given by Ker~-igan~~O and P a t t ~ n . ~ ~ l A chemical procedure for determining carbon disulphide, carbon dioxide and hydrogen sulphide in waste gases from a carbon disulphide recovery plant has been described.232 SuZpphitr diovide-This is determined by Barendre~ht"~ by continuous coulometry. The range covered is 0.1 to 100 per cent.Carbon oxys~Z~~ide--Hobbs~~~ reviews the analytical chemistry of carbon oxysulphide. S ~ h o l s ~ ~ ~ $ ~ ~ ~ describes a gas-chromatographic apparatus with thermistors, in which NN'-di- N-butylacetimide is the stationary phase, which covers the range 25 to 1000 p.p.m. Gam~jager~~' and D0ri1-g~~~ concentrate the gas by absorption in ethanolic potassium hydroxide solution or in acidic palladium chloride solution, when palladium sulphide is formed, and detect it by its catalytic effect in the reaction between azides and iodine; carbon disulphide, sulphides and hydrogen sulphide interfere. l 3 1 - u ~ ~ ~ ~ ~ absorbs the gas in ethanolic mono- ethanolamine and titrates the solution with silver nitrate after removing hydrogen sulphide and thiols. An infrared method covering the range 0.3 to 1200 p.p.m. has recently been described.240 WATER- The biggest advance in the determination of water has been the development of the coulometric cell based on absorption of tlie water bv a film of phosphorus pentoxide, with continuous electrolysis by a pair of electrodes embedded in the film.The electrolysis current at a fixed flow-rate is a measure of the water content. The basic cell has been described by K ~ i d e l ~ ~ l and modified versions by Barendrecht ,242 Czuha, Gardiner and Sawyer243 and Still and C l ~ l e y . ~ ~ * Several patterns of this cell are commercially available and it is now finding wider use. Difficulties may be experienced in the measurement of water below the 10 p.p.m. level and in the presence of hydrogen or oxygen, but this is readily overcome by the simple technique of measuring the water content at two flo~-rates.~~5 Surprisingly, this technique has been ~ a t e n t e d .2 ~ ~ The cell is also subject to interference by any gas that reacts with phosphorus pentoxide, but this has been overcome by Penther,247 who separated water and hydrocarbons by gas chromatography before passing the water to the cell. The determination of water at the p.p.m. level by gas chromatography has not been as successful. A simple technique in which the water from a 10-litre sample is collected in a column packed with a polyethylene glycol coated support at 10" C, then removed by heating to 80" C in a flow of helium, is described by Carl~trom.~~* A similar method, in which a cold trap a t -85" C is used, followed by vaporisation directly into a katliarometer, has been described732 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS [Analyst, Vol.92 by Techniques involving conversion of the water to hydrogen by reaction with calcium h~dride,2~*J~l and to acetylene by reaction with calcium carbide252 have also been described and patented253; neither of these techniques is satisfactory, and direct chromato- graphy with a column packed with Fluon granules coated with polyethylene glycol 2529253,254 or packed with microporous polymer beads255y256 is probably best. Two papers describe ionisation chambers in which the water is determined by formation of negative ions.257~~~8 Two papers describe reaction with magnesium nitride to form ammonia, which is then determined either by conductivity or with Nessler's reagent .259,260 It seems unlikely that this method would be satisfactory, as ammonia is probably absorbed by magnesium oxide, and it seems likely that the reaction of water with magnesium nitride is far from complete.A layer of magnesium hydroxide is formed and inhibits further reaction. Belcher, Otten- dorfer and West26l studied the reaction of water vapour with acid chlorides to release liydro- chloric acid, which could then be titrated. Of the nine compounds examined, PP-dimethyl- glutonyl chloride and P-methyl-P-ethylglutonyl chloride were the most satisfactory. An indirect method involves the use of the reaction with 2,2-dimethoxypropane in the presence of a catalyst to form acetone, which is determined by measurement of the infrared absorp- tion.262 A paper by K ~ b a y a s h i ~ ~ ~ describes several detector tubes for water, and examines interferences.The rather specialised instance of the determination of water in the presence of hydrogen fluoride has been studied by pap pa^.^^^ This is obviously extremely difficult and it is not at all certain that any method will give the true result. Coleman and E1kinP5 determine water vapour in a version of Gooderham's apparatus,711 in which the first rotameter is heated to 105" C to measure the steam-to-gas ratio. ANALYSIS OF LIQUEFIED OR PURE GASES Anhydrous aunmonia-Carbon dioxide is determined in anhydrous ammonia by evapora- tion of a known volume. This is decomposed with dilute acid, and the carbon dioxide is collected in excess of baryta solution, which is back-titrated with oxalic acid; in the range 5 to 50 p.p.m.the standard deviation is 3 p.p.m.266 Water in "anhydrous" ammonia is determined coulometrically by Klingel- h ~ e f e r . ~ ~ ~ The liquid ammonia is passed through a tube packed with dry potassium chloride into an electrolytic cell with a diaphragm; some potassium chloride dissolves and the potas- sium formed at the cathode reacts with the water in the sample. At the end-point the conductivity changes and relays cut off the current; the range is 1 to 1000 p.p.m. of water. Argon-Nitrogen can be determined by the intensity of emission at suitable wavelengths. At atmospheric pressure, excitation can be by means of a silent discharge,268 or by the use of a high frequency discharge.269 (Hydrogen and neon in helium, andneon and helium in nitrogen can also be determined by high frequency discharge methods.270) The determination of nitrogen in argon by gas chromatography requires concentration of the nitrogen from a large sample volume in a cooled column packed with molecular sieve 5A to obtain adequate sensitivity.' b e nitrogen is then desorbed by heating and separated from residual argon by a normal chromatographic system.271 32723273 Oxygen in argon is determined by Mit~he11,27~ who used a galvanic cell based on zirconia and calcium oxide at 950" C. The apparatus is calibrated by oxygen liberated from nickel - nickel oxide at temperatures between 1000" and 1300" C. For most purposes simpler methods are available, for example, the Hersch cell.Liquid carboiz dioside-The use of liquid carbon dioxide by atomic power stations has caused considerable work to be carried out on the analysis of the very pure gas used. The sampling of the liquid at a pressure of about 350 Ib per inch2 and the subsequent evolution of the gaseous carbon dioxide have been described.275 The "residual gases," i.e., gases not dissolved in potassium hydroxide, are measured in a capillary tube in a special apparatus (range up to 0.01 per cent. v / v ) ~ ~ ~ ; the residual gases are, if necessary, analysed by a mass spectrometer.277 The determination of hydrogen, argon, oxygen, nitrogen, methane and carbon monoxide (5 to 20 p.p.m.) by gas chromatography is described by Timms, Konrath and Chirn~ide,~'8 who trap the carbon dioxide in soda lime and the water in magnesium per- chlorate, and separate the other gases on a molecular sieve 5A, with katharometers as detectors and helium, or argon, as carrier gas.The U.K. Atomic Energy trap boron in 2 M sodium hydroxide solution and finally determine it with curcumin. Traces of oil in liquid carbon dioxide are determined At -70" C the carbon dioxide remains as carbonate.December, 19671 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS 733 by the evaporation of the sample through pure carbon tetrachloride. The residue in the sample cylinder is also extracted with carbon tetrachloride, and the oil is determined by measurement of the optical density at 2890 cm-l (C-H stretching frequency). This is valid down to 0.0005 per cent.w/v of oil in the carbon tetrachloride.280 Carbon oxysulphide can be determined (0.5 to 2700 p.p.m.) by gas chromatography on a silica-gel column at 25” C, with argon as carrier gas and an ionisation detector.281 Sulphur compounds can be determined by oxidation to sulphur dioxide, absorption in tetrachloromercurate solution and colorimetric determination. 282 Carbonyls of iron and nickel are determined by passing the gas over a quartz-wool plug at 350” C. It is cooled under argon, then the metals are extracted with dilute acid and determined spectrophotometri~ally.~~~ Oxygen is determined by K ~ y a m a ~ ~ ~ by using a galvanic cell, with potassium hydrogen carbonate as electrolyte. ChZorine-The assay of liquid chlorine for chlorine, water, residue and nitrogen tri- chloride is described in a British Stz~ndard.28~ The gas can be analysed for general impurities by gas chromatography.28G JakSiC and B ~ l i m b a S i k ~ ~ ~ determine water in gaseous chlorine by absorption in phosphorus pentoxide or magnesium perchlorate.de Vries and measure the residual gases after removing chlorine by its reaction with mercury, determining iron(II1) chloride on the residue after evaporation, silicon tetrafluoride by the molybdenum- blue reaction and chloroform by the pyridine method, although this is not specific. HeZiurn-B~urke~~~ determines permanent gases in helium at the p.p.ni. level by using a chromatograph with a P-ray “argon” detector, while Purer and S e i t ~ ~ ~ O achieve a high sensitivity with a large sample on a Beckmann GC-24, and Purer291 determines neon, hydrogen, argon, oxygen, krypton, nitrogen, methane and xenon at the p.p.m.level after a concen- tration stage. Excitation by high frequency electrodeless discharge is used by Bochkova and Cherny~lieva~~~ for determining sinall amounts of hydrogen and nitrogen, the hydrogen line used being 4816A. At a pressure of 20 torr, 10 p.p.m. of hydrogen can be determined in a 15-mm diameter tube. Nitrogen interferes, but can be neglected if less than 0-02 per cent. is present. To determine nitrogen, the lines N+, 4278’4, and He, 5047A, are used. E m r n ~ t t ~ ~ ~ determines nitrogen in helium by measurement of the intensity of Tesla discharge. Sagaidak294 uses external electrodes for determining hydrogen and states that for the range 500 to 2500 p.p.m.of hydrogen the error is + l o per cent. The conversion of a conventional mass spectrometer to determine impurities at the p.p.m. level has recently been described.295 Hydvogeiz-The analysis of electrolytic, compressed hydrogen for hydrogen, oxygen, carbon dioxide, carbon monoxide, nitrogen and mercury is described in a British Standard.296 To determine carbon monoxide in hydrogen, C i u h a n d ~ ~ ~ ~ passes the gas through an aqueous solution of the silver compound of @-sulphamidobenzoic acid at 0” C. The reagent is reduced by carbon monoxide, giving a yellow or brown colour; extinction at 420 mp is measured to determine the carbon monoxide (range 0401 to 0 . 3 per cent. of carbon monoxide). Smolkova, Felt1 and Grubner298 report on the determination of impurities in electrolytic hydrogen, and Brenner and Ettre299 isolate nitrogen and oxygen from other impurities with a condensing trap of silica gel at -80” C, Anhydrous hydro$woric acid-A U.K.Atomic Energy Authority Report300 gives full details for the analysis of hydrofluor-ic acid. The gas is dissolved in glacial acetic acid; water is determined by the conductivity of the solution and sulphur dioxide by reduction of iodine in acetic acid solution, the excess being back-titrated with tliiosulphate; total sulpliur is determined gravimetrically after oxidation with bromine water ; silicon tetrafluoride is con- verted to silicate and determined colorimetrically with molybdate ; and hydrogen sulpliide is determined by precipitation of cadmium sulpliide and iodimetry.Water is determined301 by using potassium fluoride to fix the hydrofluoric acid as potassium hydrogen fluoride and then titrating with Fischer’s reagent, and also302 by determining the electrical conductivity of the liquid hydrogen fluoride in a poly (chlorotrifluoroethylene) cell and correcting if sulphuric acid or fluorosilicic acid are present. Nitrous oxide-Nitrogen and oxygen are separated from nitrous oxide, and from each other, on a column o f molecular sieve 5A, while a column of high viscosity liquid paraffin on brick dust gives a good nitrous oxide peak.303 Oxygen-C, to C,.hydrocarbons in liquid oxygen are determined by gas chromatography, with a modified alumina ~olumn.~O~ Suzuki, Araki and Hirano305 concentrate the impurities in a cold trap and examine them with a mass spectrometer; they found nitrous oxide, carbon734 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS [Analyst, Vol. 92 dioxide, C, to C, hydrocarbons, xenon and krypton.Shinohara, Ohkusa and Okada306 evaporate 100ml of liquid oxygen through a U-trap cooled in liquid oxygen; the contents of the trap are examined by gas chromatography. The column consists of 15 metres of benzyl ether and 2 metres of silicone grease at 30" C, and a typical sample contained 3 p.p.m. of nitrous oxide, 4 p.p.m. of propane and 2 p.p.m. of butane. Alternatively, the concentrate is vaporised and analysed by infrared absorption in a cell 1 m long. The procedure of trapping the acetylene in silica gel followed by determination with copper(1) chloride reagent is although with the sensitive detectors now available it is simple to determine this impurity directly by gas chromatography.Carbon dioxide in oxygen308 (up to 10 p.p.m. of carbon dioxide) is absorbed on a molecular sieve column, desorbed by heating with a movable heater at 350" C, and determined by katharometry. FUEL GASES Coal gas-There is little to report on developments in the older methods of analysis; they continue in use virtually unchanged, but are in course of being replaced by gas chromato- graphy and other physical methods. A British Standard309 describes the sampling and analysis of fuel gases and flue gases. Densham and Gough310 reviewed the application of physical methods in the gas industry up to 1957, while Boreham and Armstrong311 have extended this review up to 1964.Colson and Brown312 describe the analysis of town gas by chromatography. They analyse for permanent gases, and for carbon dioxide, on a silica- gel column followed by molecular sieve 5A at 50" C, with helium as carrier gas, on a 1-ml sample. Hydrocarbons up to C, are separated on an alumina column (0.1 to 0.01 ml sample) with a flame-ionisation detector, the carrier ga5 being nitrogen - hydrogen mixture (60 + 40). They also describe tlie determination of tetrahydrothionaphthene, cyclopentadiene and but-l,%diene, and point out that a flame-ionisation detector can be used, e.g., in laboratories, as a portable leak-detector without a column. An apparatus for the comprehensive analysis of fuel gas by gas chromatography with five columns and an ionisation detector is des- cribed by Blakemore and hill mar^.^^^ In the analysis of coke-oven gas for minor com- p o n e n t ~ , ~ ~ ~ all except the permanent gases are condensed at liquid-air temperature in contact with Apiezon oil.The mass spectrograph was used to identify and determine twenty-eight substances present to less than 0.01 per cent. Prior chromatographic separation over squalane, or, better, benzoquinoline, gave greater enrichment and less overlapping of peaks. The numerous unsaturated compounds were hydrogenated and then identified by fourteen well separated peaks. By combination of chromatography, mass spectrography and hydro- genation, fifty compounds present from 0-0001 to 2.8 per cent. were identified. Schubert315 determines light oil in coal gas by trapping on silica gel and separating by liquid cliromatography with isopropyl alcohol, and Sudan red (C.I.Solvent red 1) as indicator instead of the fluorescent indicators used in the petroleum industry. After 45 minutes the length of the red zone is measured and the light oil determined from a calibration graph. Knipschild and Pagnier report on the determination of benzene hydrocarbons in coal gas3I6 by gas chromatography. A further paper by the same authors317 deals with naphthalene and methylnaplithalenes. An entirely different approach to tlie determination of aromatics is by means of the Hanovin benzole meter, which is essentially a simple ultraviolet photometer .318 There have been three papers on the determination of naphthalene in coal gas by tlie picrate method,319 932°9321 the last of which being the British Coke Research Association's recommended procedure.It is unlikely that any laboratory equipped for gas chromato- graphy will make much use of this old procedure, familiar to all gas works and coke-oven chemists since before 1018. A comparison of the picrate method with an ultraviolet method for naphthalene in coal gas has also been Total sulphur is determined by combustion, the products of combustion being collected in dilute hydrogen peroxide. Giinther323 describes a new apparatus and determines t h e sulphuric acid by conductinietric titration. Mi~haelis32~ describes four methods for deter- mining hydrogen sulpliicle in coke-oven gas that were studied on behalf of the German Coal Mining Association, vi?., with lead acetate paper, by precipitation as cadmium sulphide or absorption in sodium hydroxide solution, by oxidation to sulphate and by passing it through an ion-exchange column, followed by acidimetric titration. Harendrecht and J a n n ~ e n ~ , ~ describe an apparatus in which the gas is scrubbed withDecember, 19671 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS 735 water and the change in conductivity measured. This is applied to the determination of carbon dioxide and ammonia, but small and variable amounts of electrolytes interfere. B o r ~ k ~ ~ ~ determines nitric oxide continuously by oxidation with ozone and the colori- metric reaction with m-phenylenediamine, and pi err air^^^^ passes the gas through a cell in which oxygen is being electrically generated; the nitrogen dioxide formed is determined with the Griess - Ilosvay reagent.The determination of iron and nickel carbonyls in town gas has recently become of considerable importance. Densham, Beale and Palmer328 have published two methods, colorimetric and atomic absorption, which can be applied at the very low levels currently of interest. A recommended procedure is with a molecular sieve 5A column for traces of carbon monoxide, active carbon for the general analysis and activated alumina or di-octyl phthalate for hydrocarbons from Sewage sludge gas-Grune and Ch~eli~~O J~~ describe sampling apparatus and column prepration for chromatographic analysis, and, in another paper,332 the determination of methane, carbon dioxide, hydrogen, oxygen, nitrogen, hydrogen sulphide and ammonia.Natural gas-The infrared analysis of natural gas from Lacq is described by L a f a i ~ . ~ ~ ~ The pressure is atmospheric, and a double-beam instrument with a calcium fluoride or lithium fluoride prism is used. The quantitative determination of methane, carbon dioxide, ethylene, propane, carbon oxysulphide and hydrogen sulphide is discussed. The gas-chromatographic determination of nitrogen, helium, argon and oxygen, after prior concentration on a column of molecular sieve or activated carbon at solid carbon dioxide or liquid-air temperature, is described by Z i e l i ~ k k i . ~ ~ ~ K l i r ~ g m a n ~ ~ ~ discusses sampling arrangements and gas-chromato- graphic determination of helium in natural gas. Sampling and analysis are also mentioned in a review by Verrien336 of the problems arising in the exploitation of natural gas.Thiols in natural gas can be separated by gas chromatography and determined by coulometric titration (1 p.p.m. and upwards) .337 Carbon oxysulphide can similarly be determined by separation over a column of NN’-dibutylacetamide. Propane will interfere if more than 0.3 per cent. is present. Relative retention values for carbon oxysulphide and several other gases are given.236 Blast furnace gas-A U. S. Bureau of Mines Report338 describes a continuous, largely gravimetric, system for the determination of the main components in blast-furnace top gas, while a chromatographic method is described by L ~ e t h . ~ ~ ~ FLUE GASES A series of British Standards deals with the sampling and analysis of flue gases.340i341 These cover the determination of moisture (gravimetric) , dew-point, sulphur dioxide (by iodine solution), sulphur trioxide (by solution in isopropyl alcohol and titration with barium perchlorate solution), carbon dioxide (by conventional means, infrared absorption or thermal conductivity) and carbon monoxide (by infrared absorption, palladium sulphite tube, hopcalite or the iodine pentoxide method).Before the iodine pentoxide method is used, unsaturated compounds are removcd by bromine on active charcoal). “Oxides of nitrogen” are oxidised to nitrate and determined by 2,4-xylenol. Halpen and R ~ e g g ~ ~ ~ discuss the effect of sampling conditions on the apparent com- position of hot-flame gases and recommend the use of water-cooled probes.Thc use of isopropyl alcohol solution to trap sulphur trioxide (or sulphuric acid mist) and thus separate it from sulphur dioxide seems to have become standard practice in this country. Crumley, Howe and Wilson344 describe an automatic method for precipitation of the barium sulphate and optical measurement of the suspension. Fielder and c ~ - w o r l t e r s ~ * ~ ~ ~ ~ ~ describe the determination of 0.50 p.p.m. of sulphur trioxide in the presence of up to 3000 p.p.m. of sulphur dioxide. The sulphur trioxide is trapped in isopropyl alcohol - water solution, and an aliquot is titrated with 0.0025 M barium perchlorate solution, with “thoron” as indicator; the sulphur dioxide is determined with iodine. Seid~nan?~~ uses a similar method for sulphur trioxide, but he traps the sulphur dioxide in the effluent gas from the sulphur trioxide absorber in dilute hydrogen peroxide, and finally titrates the resultant sulphuric acid in the same way.Jelgersma348 dislikes the isopropyl alcohol met hod, because the sulphur dioxide must be Methane - steam reformed gas-This is analysed by chromatography. c, to q . 3 2 9 Stone343 determines the sulphuric acid by turbidimetry.736 WILSON AXD DUFF: INDUSTRIAL GAS ANALYSIS [Analyst, Vol. 92 separated from the alcohol before determination, and prefers to collect the sulphur trioxide in glycerol and measure the concentration by conductivity. Other methods involve the use of formaldehyde34g or acetaldehyde and f ~ r f u r a l ~ ~ ~ to inhibit the oxidation of sulphur dioxide.In an interesting method the gas is absorbed in a solution of iodine in barium chloride, and both sulphur dioxide and sulphur trioxide are determined from measurement of the total acidity and the iodine reduction.351 An automatic apparatus based on measure- ment of the turbidity of barium sulphate in isopropyl alcohol has been described by Grandona.352 H i ~ s i n k ~ 5 ~ describes a portable instrument for the simultaneous determination of sulphur trioxide and sulphur dioxide. The gas is cooled to below the "acid dew-point"; sulphuric acid mist is caught on a sintered-glass filter and sulphur dioxide is subsequently trapped in hydrogen peroxide. It is claimed that all of the sulphur trioxide will be trapped if the temperature is maintained at between 60" and 90" C.3549355 A continuous-recording instrument based on the colour reaction with barium chloroanilate covers the range 0.2 to 10 p.p.m.and may well receive wide appli~ation.~56 An unusual approach is that of Bond357 ; sulphur trioxide is reacted with oxalic acid to produce carbon monoxide, carbon dioxide and sulphur dioxide. The effluent gas is analysed by gas chromatography . For the analysis of flue gases containing both organic and inorganic gases, Cvejanovitch3j8 describes a gas-chromatographic apparatus with multiple columns. Retention time and thermal-response factors are given for five permanent gases and twenty-three hydrocarbons ; a complete analysis, including saturated and unsaturated hydrocarbons up to C,, takes 3 hours. Formaldehyde in combustion products can also be determined by gas chromatography ; K y r y a c ~ s ~ ~ ~ used a column of 12 feet of octyl decyl phthalate at 105" C.MOTOR EXHAUST GASES Both are titrated acidimetrically. Continued attention to atmospheric pollution has led to much work on the analysis of motor exhaust gases. King360 reviews methods of exhaust-gas analysis ; Ellis, Kendall and E c ~ l e s t o n ~ ~ ~ ~ ~ 6 ~ describe methods of sampling and determination of aldehydes, ketones, alcohols and oxides of nitrogen. A l t s h ~ l l e r ~ ~ ~ uses Mylar bags for sampling and the prepara- tion of standard atmospheres, and determines aromatic hydrocarbons by gas chromatography. Feinland, Andreatch and C o t r ~ p e ~ ~ ~ determine hydrocarbons in motor-car exhausts with two chromatographic columns in parallel, and twin flame-ionisation detectors with a common recorder. With no prior concentration, the limit of detection for butane, with a 1-ml sample, is 0.01 p.p.m.An even more complex gas chromatograph that gives a more comprehensive separation has also been described.365 I t is claimed that 85 components are separated in 13 minutes by a rapid gas-chromatographic procedure for C, to C,, hydrocarbons, in which capillary columns and programmed temperature rise are Unsaturated hydrocarbons are determined by Mader, Schoenemann and Eye367 by absorp- tion in carbon tetrachloride, followed by photometric titration with a special 0.01 1\; bromide - bromate solution. The range is 25 to 1000 p.p.m. v/v, but recovery of C, or lighter hydro- carbons is not good. Carbon dioxide can be determined in motor exhaust gases by an interference filter photometer at 4.29 pa; the range is 1 to 18 per cent.V / V . ~ ~ * Nicksic3a9 determines nitrogen dioxide in diesel exhaust gases by ultraviolet absorption. Nitric oxide is determined after oxidation to nitrogen dioxide by mixing with oxygen, and compression to accelerate the oxidation. A rapid method in which Saltzman's reagent is used is claimed to be as accurate as the phenoldisulphonic acid meth0d.~70 ANALYSIS OF XIICKO SAMPLES There have been comparatively few papers on the analysis of very small samples by modifications of absorption methods. Updegraff and H ~ c k a b a y ~ ~ l have modified thc apparatus of Berg.372 Aqueous reagents are used and a sample of 50 to 100 pl can be analysed for carbon dioxide, oxygen, hydrogen, hydrocarbons and inert gases in 15 minutes, with a precision of $0-5 to 10 per cent.for the various components. A semi-micro apparatus is described by K a d l e ~ ~ ~ ~ in which the gas burette is a tube 40 cm long, with a bore of about 2 mm diameter. The usual aqueous reagents are introduced by rolling one of two mercury globules, between which the sample is trapped, over a thin film of the absorbent in the tube, and the analysis is carried out by measuring the changes in length of the gas column. Lef~rt-37~ describes a system of micro gas analysis, which is a combination of an ionisationDecember, 19671 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS 737 chamber with separation of components by a cold trap (carbon dioxide, water and nitrous oxide), diffusion through palladium (hydrogen) or chemical reaction (oxygen).Gas-chromato- graphic methods are usually applicable to samples in this size range. The determination of gases in metals (by which the metallurgist does not necessarily mean gases absorbed or in solid solution in the metal, but any gases that are evolved on heating under specified conditions) is not really gas analysis as considered in this review, but is a subject of great and growing importance and, as it involves the analysis of small volumes of gas, it is appropriate to mention it here. The usual procedure is to heat the metal sample to a high temperature in vacuu, usually in a bath of a flux such as platinum or tin in which the sample dissolves, and often contained in an out-gassed graphite crucible.Dissolved or combined hydrogen, nitrogen or carbon monoxide is evolved, any oxygen present combines with the carbon and is also evolved as carbon monoxide, and also in most instances metal nitrides decompose and give up their nitrogen. In a report375 full descriptions of the evolution of the gases and their subsequent analysis are given. The current tendency seems to be for the use of gas chromatography to in- T y o ~ ~ ~ ~ discusses the determination of hydrogen, nitrogen and oxygen in steel by gas chromatography, and and G a l ~ e y ~ ~ ~ discuss the application of gas chromatography to the determination of trace amounts of carbon in steel. Evans and F a s ~ e 1 ~ ~ ~ determine as little as 0.003 up to 0.1 per cent.w/v of nitrogen or oxygen, or both, in steel by fusion under slightly reduced pressure by a d.c. arc; an aliquot of the resulting gas mixture is analysed on a %foot column of molecular sieve 5A. A routine analysis (coefficient of variation 2.5 to 10 per cent.) is complete in 10 minutes. hiller^^*^ determines helium and hydrogen in beryllium by vacuum fusion and gas chromatography. S u z ~ k i ~ ~ ~ analyses a 1-g sample by the vacuum fusion method, and on a molecular sieve 5A column, with argon as carrier gas, claims to determine hydrogen down to 0.00002 per cent., nitrogen to 0.0009 per cent. and oxygen to 0.0018 per cent. M i ~ k e l ~ ~ ~ describes the analysis of gases evolved during the arc melting of refractory metals.After extracting hydrogen, nitrogen and carbon monoxide from steel, Koch, Eckhard and Stricke1-3~~ analyse the mixture by high frequency excitation and spectroscopy in the visible region. Isotopic-dilution methods have also been applied to the determination of gases in In 1964, a review of later work appeared376 with 163 references. Crease.377,378,379,380,381 metalS.390,391,392,393 ATMOSPHERIC POLLUTANTS GENERAL- The field of atmospheric pollution proper has been extensively reviewed by Alt~huller,~~4,395 but he does not touch upon the wide field of industrial atmosphere analysis. The Air Pollution Control Association has recently issued a manual of standard methods for determining sulphur dioxide, hydrogen sulphide, oxidants, ozone, oxides of nitrogen, carbon monoxide, fluoride, hydrocarbons and aldehyde~3~6 A similar manual of methods for determining sulphur dioxide, nitric oxide, nitrogen dioxide, ozone, aldehydes, acrolein, formaldehyde, sulphate and nitrate has been issued by the U.S. Department of Health, Education and Welfare.397 The results of 5 years' operation of the U.S.National Gas Sampling Network, with details of apparatus and methods, have been described by Tabor and Golden.398 A compendium of methods for testing industrial atmospheres has recently been published.3g9 The collection and storage of large samples of air in plastic bags is assessed in two papers,400v401 and the use of these bags, for the preparation of standard mixtures, in a third.402 The collection of contaminants from the air by using absorbers is discussed and types of absorber reviewed in several papers.403~404~405 A special design, in which only 10 ml of reagent are used in a circulating system, is described by I<amplia~sen,*~~ and an unusual frittcd design is described by This latter apparatus is similar to a design by Bergshoeff that has been in use for 5 years408 An apparatus for the calibration of hand sampling pumps is described by Gage.409 A general-purpose apparatus is described by KUndig4l0 in which the sample is aspirated through a quartz pyrolysis tube at 1000" C, then into water in a conductivity cell; it is suitable for738 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS [Analyst, Vol.92 the determination of hydrogen sulphide, carbon disulphide and halogenated organic com- pounds, but is, of course, liable to considerable interference.Kinnea+ describes a paper tape sampler for the determination, by using suitably impregnated tapes, of hydrogen sulphide, hydrogen cyanide, phosgene, chlorine and sulphur dioxide, while Nichols412 lists modi- fied reagents for use with a commercially available sulphur dioxide meter to convert it for the determination of hydrogen sulphide, chlorine, chloride, nitrogen dioxide, fluoride or organo- chlorine; the absorber used in this apparatus is described in a British Patent.413 The use of detector tubes for the assessment of toxic hazards in factory atmospheres has increased greatly in recent years. Sa1tzman4l4 reviews theory, evaluation and calibration of detector tubes, although his remarks on the performance of commercial tubes are now out of date.Kitagawa415 also reviews detector tubes, principally his own, while Grosskopf416 reviews several types of tube, including those by Drager. Filyanskaya417 describes the technique for the preparation of silica-gel based tubes, with suggestions for tubes sensitive to hydrogen sulphide, chlorine, ammonia, petroleum, benzene, toluene and nitrogen dioxide. A useful paper describing the preparation of standard atmospheres of 16 toxic gases suitable for the calibration of detector tubes or other instruments has been published by S a l t ~ m a n . ~ l ~ ORGANIC VAPOURS- The determination and identification of organic vapours in the atmosphere presents a difficult problem. Before the development of gas chromatography, mass spectroscqpy was the only general method, and its application to the analysis of complex mixtures of organic compounds collected in urban atmospheres is described by Weaver, Hughes, Gunther, Schuhmann, Redfearn and G ~ r d e n .~ ~ ~ The simpler problem of determining hydrocarbons alone is treated by Quiram and Biller.420 The application of gas chromatography is reviewed by - 4 l t s l i ~ l l e r , ~ ~ ~ with particular reference to car-exhaust fumes, while a more general review is given by Lebbe.422 Techniques of pre-concentration and drying are described by F a r r i n g t ~ n ~ ~ ~ for the p.p.m. level, while Bellar424 and Feldstein and Ba1estrie1-i~~~ deal with the p.p.b. level. With such techniques, however, the analyst may have to choose between a system of low e f f i ~ i e n c y ~ ~ j ? ~ ~ ~ or low capacity for certain constituents of the atmosphere he is testing,427 or risk using an adsorbent that may catalyse reaction of the collected pollutant. For example, silica gel may catalyse the con- version of alcohols to olefins, although, surprisingly, molecular sieve 5A appears to be free from this defect.428 G ~ e r r a n t ~ ~ ~ describes a portable gas chromatograph with silica gel or hexadecane columns and a flame-ionisation detector for field use, and Rasmussen and Went430 describe the rough quantitative measurement of organic compounds in forest air.In a paper by West, Buddhadev, Bharnt, Mallik and Sen G ~ p t a , ~ ~ l retention results for numerous possible pollutants on columns of tritolyl phosphate and /3/3-oxydipropionitrile are listed.The application of gas chromatography to the determination of a wide range of toxic substances in factory atmospheres is fully developed by Cropper and Kamin~ky.~27 Hydrocarbow+--The modern technique for determining hydrocarbons in air involves the use of the flame-ionisation detector almost exclusively. Its use without chromatographic columns for total hydrocarbons is described by Andreach and Feinland,432 and by Decristo- far^,^^^ while separating columns for individual hydrocarbons are described by various a u t l i o r ~ . ~ ~ ~ , ~ ~ ~ 3436 9 4 3 7 9 4 2 8 The older technique of combustion to carbon dioxide followed by infrared determination by its spectrophotometric absorption in the infrared region is described by Ro~enbaum.*~~ Methane in mine air is traditionally determined by combustion over a platinum filament.A particularly sensitive design is described by Domanski, Jourdon and E y r a ~ d ~ ~ O and a catalyst for flamelsss combustion (platinum f h t s palladium on alumina) is described by Kravcl~enko.~~~ The other popular instrument, the interferometer, has been reviewed by Baker, Hartwell and Windle, with special references to the effects of other gases.442 The use of infrared spectroscopy at 7.6 p is covered by Colbasini and Watson.443 A detector tube for ethylene makes use of the reducing action of this gas on a mixture of am- monium molybdate and palladium ~ u l p l i a t e ~ ~ ~ ; this is obviously subject to interference from other reducing gases. A simple field method for determining acetylene comprises absorption on silica gel at -78" C.The gel is allowed to return to atmospheric temperature and a solution of animoniacal copper(1) chloride added; the colour produced is compared with a series of A simple chromatographic system for pollution studies is described byDecember, 19671 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS 739 permanent A method for determining conjugated di-olefins involves the use of 9-nitrophenyldiazonium fluoroborate in a 2-methoxyethanol - phosphoric acid solvent as absorption reagent; the extinction at 400 to 500 mp is used, depending on the olefin measured.447 The determination of benzene, toluene and xylene in air is best achieved by gas chromato- graphy, with, for example, a column of 5 per cent. di-octyl phthalate and a flame-ionisation detector,44* but there may be occasions when other techniques are preferred.One of these involves drawing air through methanol at solid carbon &oxide temperature for 30 minutes, followed by measurement of the extinction at 245.5, 268-5 and 272.0 mp, from which the concentration of each hydrocarbon can be calculated.449 Another ultraviolet method for determining benzene alone involves the use of a silica-gel trap, which is subsequently eluted by low boiling solvents, followed by a fractionation stage and spectrophotometry at 253 to 280 mpg50 V l a ~ a k ~ ~ l describes two methods for determining benzene that depend upon nitration, while Blake and Rose452 describe a method for determining toluene, which has been adopted as a standard method by H.M.Ministry of Labour.712 In this method the air is drawn through a solution of formaldehyde in a mixture of phosphoric and sulphuric acids until a colour of standard intensity is formed. By using 89.5 per cent. sulphuric acid alone, instead of the acid mixture, styrene can be determined without interference from either benzene or toluene. A method for determining a-methylstyrene involves the reaction with mercury(1) acetate and the colorimetric determination of the excess with diphenyl- ~arbazide.~~3 Halogen compounds-A simple general method for determining organo-halides in air involves combustion in an ethanol flame that impinges on a copper wire; in the presence of organohalogen compounds the flame is usually coloured g1-een.~54 More specific results can be obtained by application of the many variations of the Fujiwara reaction, which are reviewed by Humold and S c h ~ h l e i n , ~ ~ ~ and the best conditions for seven chloro compounds are given.A more recent modification is described by L e i b m ~ ~ n , ~ ~ ~ and a procedure suitable for chloride (but not specific) is described by Redford-Ellis and K e n ~ h . ~ ~ ' A colorimetric method for the determination of carbon tetrachloride in air is described by B e l y a k o ~ . ~ ~ ~ In this method the sample is collected in pyridine, made alkaline, allowed to react for 20 minutes at 85"C, acetic acid and aniline are added and the extinction is measured at 496mp. A general method involving reduction with sodium biphenyl and titration of the chloride ions is described by Stier.459 The most specific methods involve the use of gas chromatography, either with a collection stage460 or else directly.The extremely sensitive electron-capture detector permits the direct determination of nanogram amounts.461 B e r t ~ n ~ ~ ~ described a general method for chlorinated ethylene in which the sample is irradiated with ultraviolet light to form cyanogen chloride, and is then passed through a paper containing P-dimethyl- aminobenzaldehyde and NN-dimethylaniline. Two detector tubes for trichloroethylene with silica gel impregnated with potassium permanganate - orthopliosphoric acid or o-tolidine hydrochloride are described by Gage.463 The latter is hetter, and, if correctly calibrated, is very effective. A detector tube for vinyl chloride in which the halide is oxidised by sulphuric and chromic acids is described by I<obaya~hi.~fi~ B ~ n c z e ~ ~ ~ describes a method for ally1 chloride involving absorption in ethanolic phloro- glucinol solution, colour development, and measurement of the extinction at 520 mp.H ~ g h e s ~ 6 ~ gives a colorimetric method for 2,2-dichlorovinyl dimethyl phosphate, and BenczeP67 gives one for pentachlorophenol by its reaction with phenazole to form a blue dye; most other chlorophenols form red dyes. The use of a simple thermal-conductivity meter to determine methyl bromide in air is described by Heseltine, Pearson and W a i n i m a ~ ~ , ~ ~ ~ although this is obviously not specific. Micro-sampling apparatus for the collection of brominated hydrocarbons is described by Call.470 Dibromomethane can be determined by absorption in methanolic potassium hydroxide, conversion to potassium bromide, and the bromide determined ~oulometrically.~~~ Berck and Solomon468 describe a polarographic method for chloropicrin.ALDEHYDES AND KETONES- A review of the determination of aldehydes in air is given by Altshuller.472 The chromo- tropic acid method for formaldehyde is reviewed by A l t s l i ~ l l e r , ~ ~ ~ and a modified version is740 WILSON AKD DUFF: INDUSTRIAL GAS ANALYSIS [Analyst, Vol. 92 described in detail by the same A comparison of chroniotropic acid with the more sensitive J-acid and phenyl- J-acid is given by S a ~ i c k i , ~ ~ ~ while a fluorimetric determination, based on reaction with acetylacetone and claimed to detect 0.01 pg, is described by Belman.476 A method claimed to be specific and accurate to 5 to 10 per cent.in the pg range involves reaction with phenylhydrazine and oxygen in an alkaline medium to give a red product.477 Rayner and J e p h ~ o t t ~ ~ ~ describe a method in which Schiff's reagent is used wit11 acetone added to increase the intensity and stability of the colour. With this they claim to detect 5 p,p.b. (lo9) in little more than 1500 ml of air; they also claim a 72 per cent. collection efficiency for an impinger containing 0.005 N hydrochloric acid, sampling at 1 foot3 per minute. Another method for the p.p.b. level involves the use of acid-bleached 9-rosaniline and the dichlorosulphitomercurate complex479 and has been used successfully in a mobile laboratory for over 4 years.Silica gel impregnated with phenylhydrazine hydrochloride is used in the only detector tube for formaldehyde described during this period. After sampling, a red colour is developed by oxidation with potassium hexacyanoferrate(II1) .480 The determination of acrolein in the atmosphere can be accomplished by reaction with 4-hexylresorcinol and measurement of the spectrophotometric absorption at 605 1np.48~ A 10-litre sample is required to detect 0-1 p.p.m. Acetone may be determined in air by adsorption on activated silica gel, followed by desorption in the presence of alkali and iodimetric determination.482 Cyades-Methods for the determination of trace cyanides have been comprehensively reviewed by Bark and I - I i g ~ o n , ~ ~ ~ and alternative reagents to the carcinogenic benzidine have been investigated.484 These authors favour P-phenylenediamine but methods in which bar- bituric and P - t ~ l u i d i n e ~ ~ ~ are used as alternatives to benzidine have also been described. In a method for determining hydrogen cyanide and hydrogen sulphide, mercury( 11) nitrate is used with diphenylcarbazone as indicator.487 A simple paper-stain method based on the formation of Prussian blue has been developed by Dixon, Hands and Bartlett,488 and a booklet describing this method and including a set of standard colour stains has been published by H.M.Stationery Office.489 In another paper method, impregnation with mercury - diphcnyl- carbazide and sodium hydrogen carbonate is used; by insertion of the paper in a suitable tube the concentration can be determined by measuring the length of the red stain produced.49o o-Tolidine and copper(I1) sulphate on silica gel are used in a detector tube described by McConnaugl~ey,~~~ and one based on silver chloride or mercury( I) chloride plus bromothymol blue to detect the released hydrogen chloride is described by Hiedric11.~~~ Hydrogen cyanide and cyanogen may be separated from air by gas chromatography by using a column of tri- a ~ e t i n , " ~ or adiponitrile and the use of flame-ionisation detection is necessary to reach the p.p.m.range. An electrical method for determining hydrogen cyanide or hydrogen sulphide involves absorption in water and measurement of the e.m.f. developed between a rotating silver electrode and a calomel cell.494 Miscellaneous organic compozinds-Acrylic and methyl met hacry late monomer vapours can be determined by collection in cooled isopropyl alcohol, conversion to hydroxamic acid and reaction with i r 0 n ( I I 1 ) .~ ~ ~ Aliphatic amincs may be identified in air by collection in acid, conversion to benzamides and separation bj, paper chromatography,"~ or, alternatively, the original amines may be separated by gas chromatography. The determination of aniline by absorption in hydrochloric acid, followed bj7 diazotisation and coupling is described by Pono~narenko,~~~ while a paper-stain method in which p-dimet hyl- aminobenzaldehyde is used is described by Gernet and R ~ s s k i k h . ~ ~ ~ The determination of benzidine in air is described by Kratochvil, Langcr and I ' l a ~ & k .~ ~ ~ A method for determining carbon disulphide has been described that involves hydrolysis to hydrogen ~ulphide.~OO Dibutyl phthalate can be collected in ethanol, allowed to react with alkali and hydroxyl- ammonium chloride, and a colour developed by addition of iron(II1) Esters of other carboxylic acids interfere. Ethanediol can be determined by oxidation to formaldehyde followed by determination of the latter with chromotropic acid.502 A detector tube for ethanol in breath, based on oxidation by chromic acid under controlled temperature conditions, is described by Kitagawa and Wright.5o3 The determination of ethylene oxide in the atmosphere by trapping in silica gel, hydrolysis and reaction with acetylacetone is described by Gage,504 while a detector tube involving the sulphuric acid - dichromate oxidation is described by Kitagawa and K o b a y a ~ h i .~ ~ ~ Nitroglycerol can be determined by trapping in ethanolic potassium hydroxide, hydrolysis to nitrite and nitrate, and the nitrite determined by someDecember, 19671 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS 741 standard method,506 but in a better method gas chromatography is used with electron-capture A method for determining nitroethylene and 1-nitro-1-propene has been developed in which gas chromatography is used with electron-capture detecti0n.5~8 Nitro- benzene may be collected in 2-ethoxyethanol, reduced by zinc amalgam, diazotised and coupled with R - ~ a l t . ~ ~ ~ Fukuyama, Sato and Kimura510 describe a method for phenol that involves absorption in alkali and coupling with diazotised p-nitroaniline.The reaction of pyrilne with thiocyanogen bromide and aniline can be used for the determination of pyridine in air.511 A detector-tube field test for sulphur-containing stenching agents in liquefied petroleuni gas is described by P e ~ r i f a y . ~ ' ~ A paper by Feldstein, Ralestrieri and Levaggi on the determination of thiols by gas chromatography gives retention times, small-detection limits, flame-ionisation detector response and a trapping technique in which mercury( 11) cyanide is used.513 Another paper describes a similar technique.514 Methods for determining tolylene-2,4-di-isocyanate, involving hydrolysis, diazotisation and coupling with AT-1-naph- thylethylenediamine, are described by Reilly5I5 and M a r ~ a l i .~ ' ~ A detector tube for vinyl chloride in the presence of ammonia involves the use of silica gel to separate the gases, before the vinyl chloride is determined by reaction with chromic a ~ i d . ~ l 7 INORGANIC GASES- Ammonia-The determination of ammonia in air is simple and obvious. The standard method of absorption in dilute acid, followed by determination with Nessler's reagent does not appear to have been credited with separate publication. This method cannot be adapted for continuous monitoring, however, and, for this purpose, recourse is made to measurement of the spectrophotometric absorption by the gas at 204.3 mp. Two papers by K0lbezen5~8 and Gunther, Barkley, Kolbezen, Elinn and Staggs519 describe this technique for the range 10 to 1000 p.p.m., differing mainly in the model of spectrophotometer used.A detector tube for ammonia, in which thymol blue and sulphuric acid are used on a methacrylate support, is described by Kobayashi, Matsumoto and Yamada,520 while a complex tube for ammonia and etlianolamine with ninhydrin on silica gel is described by Williams and Miller.521 Of the colorimetric methods available, the indophenol reaction is probably the most robust5229523 and can be made more sensitive by extraction of the colour into isopentyl alcoh01.~~4 The most sensitive method is probably the reaction with indanetrione hydrate525 or one of the several procedures in which chloramine is used, with the subsequent formation of a blue starch - iodine complex.526 These procedures require highly skilled analysts for their application. A galvanic cell for the determination of ammonia involves the use of a neutral electrolyte with aluminium and carbon electrodes527; this cell responds to many alkaline or acidic gases.In another continuous-recording instrument recently described titration with coulometrically generated hydrogen ions is ~ t i l i s e d . ~ ~ ~ Arsiize-A detector tube for determining arsine in air in the range 1 to 50 p.p.m. involves the use of silica gel impregnated with mercury(I1) chloride.529 Bormzes-These can be determined down to 0.2 p.p.m. by scrubbing the air with sodium hydrogen carbonate - potassium iodide solution, followed by coulometric titration with iodine.530 This metliod is obviously not specific.Cnrhofz dioxide-There are numerous chemical met hods available. Toran and H e i n r i ~ l i ~ ~ l pass air through a suspension of an insoluble carbonate and measure the pH, while Lodge, Frank and FergusorP2 improl-e on this by using fine marble chips. D e ~ k e r t ~ ~ ~ absorbs the carbon dioxide in 0.25 per cent. ammonia in ethanol at 80" C and titrates the solution with thymolphthalein indicator, or else uses 0.1 N ethanolic potassium hydroxide in three impinger bubblers and titrates between phenolphthalein and methyl-red end-points. It should be remembered that the absorption of carbon dioxide is relatively slow, even in alkaline solution. A colorimetric method with 0.001 N sodium hydrogen carbonate and added phenol red, with measurement at 690 mp, can be used in a continuous while a similar method has been developed for field use, with the well known Lovibond disc method of colour com- parison.535 Another simple field method involving titration, but in which the titrants are manipulated in hypodermic syringes to exclude contamination, has also been developed.536 In several simple instruments for the nieasuremcnt of carbon dioxide at about the 1 per cent.level, diffusion between two porous pots is involved, one pot containing moist soda lime and the other cotton-wool coated with calcium chloride to produce a pressure difference propor- tional to the concentration.537 These instruments are cheap and robust and the results are742 WILSON AND DUFF: INDUSTRIAL GAS AKALYSIS [Analyst, Vol.92 surprisingly reproducible. Two detector tubes have been described. In a sample of air is drawn through a tube packed with alumina impregnated with 0.4 N sodium hydroxide and thymolphthalein by means of a hand pump. In the other539 the tube is filled with acid- washed sand coated with rosaniline hydrochloride that has been decolorised by hydrazine hydrate, and the tube is evacuated before sealing. I t thus draws its own sample when the seal is broken. A recording conductivity analyser is described by Holm- Jen~en.54~ Carbon monoxide-Detector tubes for the determination of carbon monoxide in air have been used for many years and a wide range is now commercially available. With some, the precision is not as high as could be desired and reporting a comparison of four such types of tube, showed differences among them indicating that some were as much as 100 per cent.high. The performance of one such type of tube has been examined in detaiLM2 The interference from oxides of nitrogen may be overcome by passing the sample first through a tube packed with silica gel impregnated with a solution of chromic oxide in sulphuric The “detector” plate544 consists of a plastic plate with an inserted disc of silica gel impregnated with palladium chloride, which darkens in the presence of carbon monoxide, the time taken being an approximate measure of concentration. A similar technique can be used with paper soaked in a solution of gold(II1) chloride and arsenic(II1) oxide, which darkens on exposure to carbon monoxide545; with neither technique is a sample of defined size used, so that the indications are largely qualitative.A simple but precise instrumental method that has received much attention in this period makes use of the temperature rise in the air stream when carbon monoxide is oxidised over a catalyst such as hopcalite546+7~548~54g and is useful when a continuous monitor is required, as in coal mining. A spectrophotometric method fully described by Ci~handu~~O 9551 relies on the reduction of the silver salt of $-sulpliamylbenzoic acid to give a silver sol. This method is very sensitive and is not affected by the presence of hydrogen. Finally, an electrochemical method involves the oxidation of carbon monoxide at a vibrating electrode immersed in a solution of borax or sodium dihydrogen orthophos- phat e .552 CarbonyZ chZoride (phosgene)-A qualitative indication of the presence of phosgene in the atmosphere can be obtained by the use of detector crayons.These consist of blackboard chalk impregnated with a solution of 4-benzylpyridine and barbituric acid. A line drawn by this chalk on paper will change colour in the presence of ph0sgene~5~; an alternative indicator can be prepared by soaking filter-paper in a solution of anabasine or a related alka- 1 0 i d . ~ ~ ~ A more precise paper-stain method involves drawing a measured volume of air through a paper impregnated with 4-9-nitrobenzylpyridine and N-ben~ylaniline.5~~ The colour produced is compared with a standard colour chart obtainable from H.M. Stationery Office, together with the booklet describing the method.Chemical methods are described by T e r e n t ’ e ~ , ~ ~ ~ who uses the reaction with hexamethyleneimine and by Crummett and M~Lean,~5’ who use the reaction with aniline to form 1,3-diphenylurea, which they measure by its absorp- tion at 257 mp. An extremely sensitive method involves the use of a gas-chromatographic separation on a column of didecyl phthalate and an electron-capture detector55R; it is claimed to cover the range 0.001 to 2 p.y.m. v/v. Chlorine-The o-tolidine method, popular so long for determining chlorine in air, is likely to fall into disuse because of the suspected carcinogenic properties of o-tolidine. A suitable alternative is to be found in diethyl-~-phenylenedia~nine.~~~ Other, more complex, methods involving the oxidation of iodide to iodine are described by Hollata and Mei~sner~~O and K ~ g a n .~ ~ l A simple but precise method used depends upon absorption of the chlorine in carbon tetrachloride and measurement of the ultraviolet extinction at 335 mp562 Chlorine dioxide-This can be monitored by dissolution in water followed by cathodic reduction to chlorine ; under controlled conditions the current can be made proportional to the chlorine dioxide ~oncentration.~63 Fluorine and JEuorides-The determination of fluorine, hydrogen fluoride and particulate fluorides is largely a problem of collection and separation from interfering substances. Gwirtsman, Mavrodineau and Coe564 give a detailed description of a method that involves absorption in sodium hydroxide, steam-distillation and titration with thorium(1V) solution.Pack and Hi11565 evaluated glass-fibre filters for the collection of fluorides and found 95 per cent. efficiency until 76 pg of fluorine per sq. inch of filter area had been collected. Vrotek, Pozigun and Pokraka5G6 prescribe conditions for determination by iron( 111) thiocyanate and Rough qualitative indicators are gaining popularity as “substitute mice.”December, 19671 WILSON AND D U F F : IKDUSTRIAL GAS AKALYSIS 743 list interfering anions. Guntz and Arkne567 studied the factors affecting the thorium alizarin sulphonate method. Methods involving the bleaching action on methyl red are described by P e r e g ~ d , ~ ~ ~ and in a U.K.A.E.A. Report.569 In the same paper568 Peregud describes a technique in which the reaction with potassium bromide to release bromine, which converts fluorescein to eosin, is used, with measurement of the colour produced (this is not specific as chlorine acts in a similar way).In the following year Peregud and B0ikina5~0 described a detector tube for fluorine dioxide that is based on the same principle. Some of the above methods, although described for fluorine in air, are likely to be equally sensitive to hydrogen fluoride and its inorganic salts, and the same is probably true of many methods described for hydrogen fluoride. For example, the method described by Huygen,571 in which the hydrogen fluoride is collected by drawing the air through paper impregnated with potassium hydroxide and the fluoride determined by cerium(II1) - alizarin complexan, will, of course, enable the total fluoride content of the air to be determined. This is probably also true of a method involving bleaching of a reagent prepared by dissolving titanium( IV) hydroxide in chromotropic and perhaps to a lesser extent of a method in which the hydrogen fluoride is converted to fluorosilicic acid, which is then determined by a molybdenum-blue method.573 The separation of hydrogen fluoride from other atmospheric fluorine compounds is extremely difficult and there is no really satisfactory method.574 The trouble is caused by the ability of almost every surface to absorb hydrogen fluoride, and one author effects the separation by removal of the hydrogen fluoride from the air stream by passing it through a series of concentric aluminium tubes or glass tubes coated with sodium hydrogen carbonate.The particulate fluorides pass to an impinger, where they are determined separately.575 In one method responding to some organofluorine compounds, as well as to fluorine and fluorides, a form of flame-emission spectroscopy is used but a sensitivity of only 50pg of fluorine per litre is ~ l a i m e d . ~ 7 ~ series of papers by Adams and co-workers describes a continuous automatic analyser, in which zirconium - Eriochrome cyanine R reagent is used, and the colour change is measured; this instrument detects down to 5 pg per cu. m.5779578*579 Ivie, Zielenski, Thomas and Thompson580 describe a continuous operating instrument in which sodium hydrogen carbonate coated tubes are used to give a differential measurement indicating the hydrogen fluoride concentration.Detection is by quenching of the fluorescence of a paper tape impregnated with the magnesium salt of 8-hydroxyquinoline ; this apparatus is sufficiently robust to have survived 2 years of field use. A portable analyser for gaseous fluorides (hydro- gen fluoride) depends upon absorption in acetic acid and detection with a fluoride-sensitive aluminium - platinum electrode pair.581 Hydrogen peroxide-A detector tube for hydrogen peroxide has been described, based on silica gel impregnated with ethanolic titanium( IF’) sulphate solution. Hydrogen peroxide in the air changes the colour to yellow.582 Lead-Lead is not a gas, but there are volatile organo-lead compounds and for this reason the inclusion may be justified.In the chemical determination of lead, dithizone is the preferred method and has been adopted for lead “fume” by the Ministry of Labour.583 This method, which involves collection on fiiter-payer, dissolution in nitric acid - hydrogen peroxide mixture and extraction into dithizone, followed by comparison of the d o u r with standards, was developed originally by Dixon and Mets01-1.~~~ A convenient method of evaluating the lead content of the filter-payer (for those with access to the necessary equip- ment) is to use X-ray A similar method for organolead compounds in which the compounds are trapped on crystals of iodine, followed by dissolution in acidic potassium iodide, is described by Snyder and Henderson.586 An authoritative paper by Moss and B r ~ w e t t ~ ~ ~ discusses the separation and determination of inorganic particulate lead and lead alkyls.Tetramethyl and tetraethyl-lead are oxidised by aqueous iodine monochloride solution to dialkyl-lead ions, which are determined by reaction with dithizone. Mercztry-A simple and effective met hod for determining mercury has been de~cribed.~88 In this method the mercury is trapped in permanganate solution, followed by extraction into dithizone solution until the colour just changes; a similar amount of dithizone is then titrated with standard mercury solution to the same colour. In another simple method iodised activated carbon is used to trap the mercury, which is subsequently volatilised and passed through a selenium sulphide paper where a stain is formed.58Y A detector tube is described by Draige~-590 that is based on the reducing action of mercury on mercury(T1)744 WILSON AND DUFF: INDUSTRIAL GAS AKALYSIS [Analyst, Vol.92 bromide. The mercury(1) bromide thus formed in turn reduces gold(II1) bromide to produce a gold sol. Nickel carbonyZ-Despite its extreme toxicity, there has not been much work carried out on the determination of nickel carbonyl in air. The best methods available are probably simple adaptations of those recently developed by the gas industry328 and the U.K.A.E.A.283 Apart from these there are several Russian methods in which either the nickel or the carbon monoxide after decomposition is determined. Belyak0va5~~ absorbs and decomposes it in a solution of chloramine B in hydrochloric acid and ethanol, while Fikhtengol’ts and K o z l ~ v a ~ ~ ~ collect it in a solution of iodine in carbon tetrachloride; in both a colorimetric finish based on dimethylglyoxime is used.On the other hand, Peregud and B ~ i k i n a ~ ~ ~ describe two detector tubes, one containing silver nitrate coated silica gel that gives a black stain sensitive to 5 pg per litre, and the other containing molybdovanadophosphoric acid coated silica gel giving a blue stain sensitive to 1 pg per litre. Nitrogen oxides-The general method for nitrogen dioxide involves absorption in alkali followed by colorimetric determination of the nitrite ion produced. Over the past 10 years Saltzman reagent (naphtliylethylenediamine) has gained precedence over the Griess - Ilosvay reagent (cc-naphthylamine) in the air-pollution field, and detector tubes are becoming accepted for industrial hygiene.compared the A.P.H.A. and Griess - Ilosvay methods, and two detector tubes, with the phenoldisulplionic acid method, in which the nitrite is con- verted into nitrate before determination. He found the detector tubes gave wide variations in response, and even the Griess - Ilosvay method could vary by +_50 per cent. Similarly, considers the phenoldisulphonic acid method best, at least down to 16 p.p.m. A method based on absorption in alkali followed by measurement of the ultraviolet absorption by the nitrite ion at 355 mp is described by Altshuller and W a r t b ~ r g , 5 ~ ~ while a direct measurement at 400 mp in a gas cell can be used at higher concentration^.^^^ Very low concentrations can be determined by inirared absorption at 4-5 p, by using a long path cell,597 but another worker has suggested that interference by water vapour makes this method un~atisfactory.~~~ Before applying an ultraviolet method, Nicksic and H a r 1 ~ i r - 1 ~ ~ ~ ~ dry the sample over calcium sulphate, presumably losing much of the nitrogen dioxide at the same time.As they were interested in car-exhaust gases in which the main oxide present is nitric oxide, this may not have been important, and they offer an interesting pressure - oxidation technique to speed up the conversion of nitric oxide in the dry gas. Many detector tubes have been described, all based on silica gel impregnated with an organic reagent, such as o-tolidine hydrochloride,600 tetraphenylbenzidine,601 diphenylamine,602 benzidine hydrochloride and 2-naphthoPo3 or $-aminobenzoic acid.604 Many of these do not appear to have been exploited commercially.A continuous automatic recording apparatus based on the use of Greiss - Ilosvay reagent is described by while Jacobs and Hochheiser606 describe one in which naphthyl- ethylenediamine is used. Saltzman607 describes a modified reagent for use in continuous recorders, and Pierce, Tokiwa and Nishikawa608 report the absorption efficiency obtained by using this formulation, among others. For rapid response the addition of R-salt is sug- g e ~ t e d . ~ ~ ~ Saltzman and WartburgGlO described a flow-dilution system for the preparation of standard atmospheres, and in tests of the Griess - Saltzman reagent found 1 mole of nitrogen dioxide is equivalent to 0.7% mole of sodium nitrite. This is confirmed by Kossano and Cooper,611 who use a similar apparatus, but Stratmann and Buck claim a 1 to 1 relationship,612 while Faucett613 shows the factor to depend on the ratio of nitric oxide to nitrogen dioxide.An electrolytic generator for both nitric oxide and nitrogen dioxide that looks extremely elegant has been described by Hersch and D e ~ r i n g e r . ~ ~ ~ Tt is well known that the absorption and oxidation of nitric oxide is extremely difficult to effect. K o n t o r o ~ i c h ~ ~ ~ tested the oxidation by permanganate solution on mixtures containing 1 per cent. of oxygen and 100 to 1000 p.p.m. of nitric oxide, with satisfactory results, while Anderson6I6 described a method in which alkaline permanganate is used to oxidise nitric oxide to nitrogen dioxide, followed by deter- mination as nitrite.On the other hand, Ripley6I7 oxidises nitric oxide to nitrogen dioxide by passing it through a glass filter impregnated with sodium dichromate and sulphuric acid. The direct determination of nitric oxide can be achieved by gas chromatography, and a method in which a molecular sieve column and argon ionisation detector are used has been described by Kipping.”lR Ozone-A review and investigation of seven methods for the determination of ozone also describes a simple ozone generat0r.6~~ The commonest method for determining ozoneDecember, 19671 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS 745 depends upon the oxidation of potassium iodide and titration of the iodine released.Wadelin620 describes a method sensitive to 2 parts in los of ozone or other oxidants. The light sensitivity of acidic potassium iodide can be overcome by using a phosphate buffer, with acidification just before titration.621,622 A simple method based on the detection of the pH change in a 2 per cent. potassium iodide solution by an indicator, and measurement of the volume of gas required to produce this change, is described by B r i t a e ~ , ~ ~ ~ and another based on tlie reddening of iron(II1) oxide - potasium thiocyanate paper, by Deckert.624 Two colorimetric methods have been described, one in which N-phenyl-@-naphthylamine in dichlorobenzene solutior, is used,Wz5 and in the other sodium diplienylaminesulpl~onate in perchloric acid.626 Both are claimed to be relatively free from interference by nitrogen dioxide and other oxidants.An ingenious method is used with gallic acid as an ozone acceptor and rhodamine B as a chemi- luminescent indicator."' A continuous automatic determination in the range 0 to 100 parts per hundred million has been described,628 with direct ultraviolet absorption in a 300-foot path gas cell, but simpler monitoring instruments have been described based on electro- chemical methods. For example, if a platinum electrode is covered with a thin film of neutral potassium iodide solution the iodine liberated by ozone produces a measurable flow of current,629 but in a more efficient reaction the halogen is reduced at the electrode.630 A com- bined ozone and sulphur dioxide analyser is based on the liberation of iodine by ozone and the consumption of iodine by sulphur dioxide ; the iodine is measured arnperometrically.The ozone is removed from the sulphur dioxide side by absorption by iron(l1) sulphate, and the sulphur dioxide from tlie ozone side by a chromium(I1I) oxide - pliosphorus pentoxide mixture.631 PhosjJhine-A detector tube for phosphine has been described by Nelson and Milun632 in which silica gel impregnated with silver nitrate is used and is subject to interference by arsine, stibine and hydrogen sulphide. In a sensitive conductinietric method the reaction with mercury( 11) chloride is used to release hydrogen chloride, which raises the conductivity of the solution.633 Radon- Radon is conveniently measured by means of its radioactivity, and two methods in which concentration on active charcoal to achieve a high sensitivity is used have been de~cribed.6~~ ,635 Stibiize-A met hod for stibine has been described involving absorption in iodine solution followed by colorimetric d e t e r r n i n a t i ~ n .~ ~ ~ Hydrogm suZ@ide-The classical determination of hydrogen sulphide by lead acetate has been adopted as a paper-stain technique by the Ministry of Labour, and a chart of standard stains is pr0vided.6~' A series of field methods covering the range 0.0001 to 0.06 p.p.m. is reviewed by Smith, Jenkins and C u m m i n g ~ o r t h , ~ ~ ~ who record a preference for silver nitrate impregnated paper. Probably the best method at the p.p.b. level is that based on the methylene-blue reaction, which is described in detai1.639 9640 y641 The efficiency of absorption of hydrogen sulphide by sodium hydroxide in a Dreschel bottle and fritted bubbler has been shown to be greater than (30 per cent., at rates up to 3 litres per minute.G42 one paper describes the quantitative collection of hydrogcn sulphide from the atinospliere with a filter- paper impregnated wit11 potnssiuni 11 ydroxide, potassium zincate and glycerol followed by a methylene-blue A combincd method for determining hydrogen sulphide and carbon disulpliide involves absorption in metlianolic potassium hydroxide.G44 In this method, carbon disulphide forms potassium methyl xanthate, whicli absorbs at 392 mp, and hydrogen sulphide forms potassium sulphide, which absorbs at 229 mp.Another method depends on the colour formed on reaction with decolorised thiofluorescein solution.645 In a turbidimetric procedure claimed to be an alternative to the methylene-blue method, the sol produced from reaction with bismuth acetate is A detector tube, involving the dis- coloration of copper sulphate deposited on an inert support is de~cribed."~ An instrumental method suitable for continuous monitoring, with a paper tape impregnated with lead acetate and sodium acetate and coated with gelatin, covers the range 0 to 500 ~ . p . m . , ~ ~ ~ but field experience has shown that large errors may result from fading of the stain if the sampling period is pr0longed.64~ This may be ameliorated by the incorporation of orfho-phenylphenol in the reagent, or by replacement of the lead acetate by mercury(I1) chloride.650 ,4 much more sensitive instrument is based upon absorption in a stream of liquid flowing in a spiral fashion down a rod, the hydrogen sulphide being determined by its quenching action on the fluorescence of tetra-acetoxymercurifl~orescein.6~~ A crude method of monitoring the hydrogen sulphide746 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS [Analyst, VOl.92 content of the atmosphere is described by Gilardi,652 who uses a tile coated with lead acetate in the way in which the “lead candle” is used for sulphur dioxide. Sulphur dioxide-A handbook of recommended methods, both manual and instrumental, which also incorporates reviews of all the rejected methods, has been published by the U.S. Department of Health, Education and Welfare653; this is a most comprehensive publication.Reviews of methods have also been published by Th0enes,~5~ Herrmann656 and Thomas.657 Herrmann also reviews methods of preparing standard concentrations, and Thomas includes consideration of the results in his paper. H o c h h e i ~ e r ~ ~ ~ examines the results obtained by using three techniques in several American cities and considers the effect of filtering the samples. The sampling procedure has been examined by Stratmann and Buck,6sg who compared the efficiency of silica gel and tetrachloromercurate, and the errors in the associated method, and by Urone, Evans and Noyes,660 who used sulphur-35 tracer to compare a conductivity analyser with the tetrachloromercurate method. They found the conductimetric sampler to be unreliable below 0.1 p.p.m.Huygen661 describes its collection by using a filter-paper impreg- nated with potassium hydroxide and glycerol, on which it is claimed the sulphur dioxide may remain unoxidised for several weeks, while Pate662 describes a similar technique for the range 0.1 to 10 p.p.m, in which “Millipore” filters impregnated with 5 per cent. potassium hydrogen carbonate are used. Easily the best colorimetric method is that of West and Gaeke,6e3 in which the sulphur dioxide is trapped in sodium tctrachloromercurate, reacted with 9-rosaniline hydrochloride and formaldehyde, and the colour developed measured at 660 mp. The interference by nitrogen dioxide in this method may be overcome by the addition of sulphamic acid to the ab~orbent.66~9~~~ The influence oi various forms of p-rosaniline has been studied by PateGB6 and a continuous analyser has been described in which the gas is absorbed directly by the p-rosaniline reagent.667 A modified method suitable for portable meters with a short sampling period has also been described,668 while others in which rosaniline chloride669 and @-aminoaz~benzene~~~ are used are claimed to give more stable and reproducible colours.In Britain, a simple method involving absorption in “neutral” hydrogen peroxide and titration of the acid formed has been standardised for use in a national survey.671 Although crude and subject to interference, this method is simple enough to be operated by non-scientifically trained personnel. The possibility of loss of sulphur dioxide by adsorption on the components of this apparatus has been examined.672 The absorption efficiency of the Drechsel bottle used in this method has been found to be 99 per cent.,673 and in another study of similar bubblers the efficiency was found to be 97 per cent.674 Another method in which oxidation was used, but this time with potassium chlorate, the sulphate being determination by titration with barium chloride, has also been described.675 At the higher concentiations that are of interest in industrial hygiene, i.e., p.p.m.instead of parts per hundred million, the standard method in this country is to use the stain produced on a paper impregnated with ammoniacal zinc n i t r o p r u s ~ i d e . ~ ~ ~ , ~ 7 ~ A detector tube containing silica gel impregnated with iodine and 4,4’-tetramethyldiamino- diphenylmethane has been described by Kobayashi J678 and patented by McC~nnaughey,~~~ The sulphur dioxide concentration is measured by the length of the decolorised layer when a sample is drawn through the tube.In a similar type of tube the bleaching effect on starch - iodine deposited on “Sterchamol” inert support is used,680 while an alternative form with silica gel impregnated with ammonium metavanadate depends upon matching stain colours.681 The need to monitor the atmosphere around power stations has led to the development of several instruments, some simple and others expensive ; sensitive and precise German instru- ments have been described by EngelhardP2 and Fuhrniann.‘ja3 Cummings and Redfearn6g4 describe an extremely good semi-portable colorimetric instrument based on the bleaching of a starch - iodine reagent along with a more precise, but much more cumbersome] con- ductivity analyser.The starch - iodine reagent is subject to interference by nitrogen dioxide and ozone, but both of these may be removed by catalytic reduction over platinum without affecting the sulphur dioxide c ~ n c e n t r a t i o n . ~ ~ ~ This instrument can be modified to operate a recorder.686 Recently a semi-portable continuous recording instrument based on the con- ductivity principle ] after absorption in hydrogen peroxide, has been des~ribed.6~’ In this instrument the contaminant is absorbed by the reagent when the stream of air impinges on the surface, a technique that has led to the development of a completely portable instru- ment688 and a pocket-sized transistorised Electrochemical methods have been described by Berton,”O who used micro piles of lead and oxidised copper, and Novak,egl who In this method interference by hydrogen sulphide is slight.December, 19671 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS 747 used a polarisable electrode such as carbon as an indicating electrode.A continuous polaro- graphic recorder has been developed in Czechosl~vakia.~~~ In a coulometric apparatus, oxidation of the sulphur dioxide by electrically generated bromine, with potentiometric end-point detection, is used.693 B e r ~ i n ~ ~ ~ has described a complex method in which the sulphur dioxide is allowed to react with sodium chlorite to release chlorine dioxide, which in turn reacts with a C6H4(OH) ,Kr clathrate to liberate krypton-85, which is trapped and counted by normal radiochemical methods.Another radiochemical method involves the release of radioactive iodine and is claimed to cover the range 8 x Methods of calibrating these instruments have been developed by D u c k ~ o r t h ~ ~ ~ and by Kuczynski .697 A technique for the calibration of field monitors with standardised gas mixtures despatched by post in polythene-lined cardboard boxes from a central laboratory has also been de- scribed.698 The old, simple instrument, the lead candle, will become less frequently used now that more sophisticated apparatus is readily available, but its replacement will un- fortunately be slow as a large body of more or less qualitative data based on this method is available.The method is described in detail in British Standards699 and by Thomas,700 and recently an improved simplified method has been described by B0wden.70~ A study of the critical parameters, such as particle size and binder concentration, has also been reported.702 A very sensitive method based on the ring-oven technique and capable of detecting 0.1 pg has been developed by Huygen.703 An indirect ultraviolet method involves the absorption by lead(I1) ions, which are reduced when lead sulphite is precipitated.704 Sulphur trioxide-There is no completely satisfactory method of measuring sulphur trioxide in air.705 I t is likely that it is present as sulphuric acid droplets and, on this basis, a method involving collection on filter-paper, extraction with borax and back-titration with 0.01 N sulphuric acid has been ev0lved.~O6 A continuous analyser can be developed from the Thomas A ~ t o m e t e r .~ ~ ~ A detector tube for acid mist in air contains silica gel impregnated with potassium bromide, potassium bromate, potassium hydroxide and fluorescein ; acid liberates bromine, which converts the fluorescein to eosin, and the stain length is a measure of c o n c e n t r a t i ~ n . ~ ~ ~ Acids other than sulphuric acid have the same effect. 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Special Technical Publication No. 281, 1959, p. 27. Snydcr, L. J . , and Henderson, S. R., Analyt. Chem., 1961, 33, 1175.Moss, R., and Browvett, E. V., Analyst, 1966, 91, 428. Drew, R. G., and King, E., Ibid., 1957, 82, 461. Sergeant, G. A., Dixon, 13. E., and Lidzey, R. G., Ibid., 1957, 82, 27. Lkager, 0. H., British Patent 811,405, 1959; Analjit. Abstr., 1959, 6, 3236. Belyakova, A. A., Zau. Lab., 1960, 26, 158. Filthtengol’ts, LT. S., and Kozlova, N. P., Ibid., 1957, 23, 917. Peregud, E. A, and Boikina, B. S., Ibid., 1963, 29, 674. Gill, W. E., U.S. Atomic Energy Commission Report HW-30331, 1958. Altshullcr, A. P., and Wartburg, A. F., Analyt. Chem., 1960, 34, 174. Comer, S. W., and Jenscn, A. V., Ibid., 1964, 36, 799. Rirkeland, J . IV., and Shaw, J. H., J . Opt. SOC. Amer., 1959, 49, 637. Chan, J., .4rchs. Envir. Hlth, 1963, 7, 13. Nicksic, S . W., and Harkins, J., Analyt. Chem., 1962, 34, 985.Kobayashi, Y., and Kitagawa, T., J . Chem. SOC. Japan, I n d . Chem. Sect., 1965, 58, 651; Analyt. British Patent 854,367, 1961. Filyanslraya, E. D., Trudy Nauch. Sess. Vses. Nauch. I n s t . Okhranjj Truda, 1954, 1, 205; Analyt Mokhov, T,. :I., and Khalturin, V. S., 1,ab. Delo, 1958, 4, 26; Anal-yt. Abstr., 1959, 6, 365. Mokhov, L. A., Udalov, Yu. F., and Khalturin, V. S., Zh. Prikl. KJziw., Leningr., 1959, 32, 452; Thomas, 31. D., Analyt. Chem., 1956, 28, 1810. Jacobs, M. H., ancl Hochheiscr, S., Ibid., 1958, 30, 426. Saltzman, R. E., Ibid., 1060, 32, 135. Picrcc, L., Tokiwa, Y., and Nishikawa, K., J . A i r Pollidt. Control Ass., 1965, 15, 204. T,yshkow, N. ll., Ibid., 1965, 15, 481. Saltzman, B. E., and Wartburg, i\. F., -4nalyt. Chcm., 1965, 37, 1261.liossano, A. T., and Cooper, H. B. H., J . A i r Pollut. Codrol Ass., 1963, 13, 518. Stratniann, H., and Huck, &I., I n t . J . A i r [Vat. Pollut., 1966, 10, 313. Faucett, H. L., 3LlcKight, T. C., and Graham, H. G., jun., Analyt. Chem., 1966, 38, 1091. Hcrsch, P., and Deuringer, R., J . Air Pollut. Control Ass., 1963, 13, 538. Kontorovitch, L. RI., T r u d y Gos. Nauch. i Pvoektn. Inst. Azotn. Prom., 1954, 218; Analyt. Abstr., Andcrson, J . H., Nature, 1964, 202, 1330. Ripley, D. L., Clingenpeel, J. M., and Hurn, R. W., Int. J . A i r Wat. PoZlut., 1964, 8, 455. Kipping, P. J., Nature, 1963, 201, 1314. Hendricks, R. H., and Larsen, 1,. R., Anzer. I n d . Hyg. Ass. J . , 1966, 27, 80. Wadelin, C. \V., Analyt. Chenz., 1957, 29, 441. Hunold, G. A., and l’ietrulla, FV., Z .arzalyt. Chem., 1959, 165, 20. __ , Ibid., 1961, 178, 27. Hritaev, A. S., TrudF Tsentr. Aerol. Observ., 1960, 13; Analyt. Abstr., 1962, 9, 1694. Deckert, W., Z. analyt. Chenz., 1956, 153, 189. ,4bstr., 1957, 4, 77. Abstr., 1957, 4, 2941. Analyt. .4 bstv., 1959, 6, 4980. 1958, 5, 1811.December, 19671 WILSON AND DUFF: INDUSTRIAL GAS ANALYSIS 757 625. 626. 627. 628. 629. 630. 631. 632. 633. 634. 635. 636. 637. 638. 639. 640. 641. 642. 643. 644. 645. 646. 647. 648. 649. 650. 651. 652. 653. 654. 655. 656. 657. 658. 659. 660. 661. 662. 663. 664. 665. 666. 667. 668. 669. 670. 671. 672. 673. 674. 675. 676. 677. 678. 679. 680. 681. 682. 683. 684. 685. 686. 687. 688. 689. 690. 691. Dellman, A. D., Ruff, A. E., Simms, B. B., and Allison, A. R., Adzi. Chem. Ser., 1959, 21, 119; Bovee, H. H., and Robinson, R. J., Analyt. Chem., 1961, 33, 1115. Bersis, D., and Vassiliou, E., Analyst, 1966, 91, 499. Renzetti, N. A., Analyt. Chem., 1967, 29, 869. Brewer, A. W., and Milford, J . R., U.S. Patent 3,038,848, 1962. Hersch, P., and Deuringer, R., Analyt. Chem., 1963, 35, 897. Schulze, F., Ibid., 1966, 38, 748. Nelson, J . P., and Milun, A. J., Ibid., 1957, 29, 1665. Greenfield, S., Moule, H. A., and Perry, R., Analyst, 1966, 91, 10. Fontan, J., Blanc, D., Bonnafous, M., and Houville, A., Chim. Analyt., 1962, 44, 392. Cadudal, C., J. Phys. Radium, 1955, 16, 479. Holland, R., Analyst, 1962, 87, 385. H.M. Factory Inspectorate, Ministry of Labour, “Methods for the Detection of Toxic Substances in ,4ir,” Booklet No. 1, Hydrogen Sulphide, H.M. Stationery Office, London, 1960. Smith, A. F., Jenkins, D. G., and Cummingworth, D. E., J . A p p l . Chem., 1961, 11, 317. Jacobs, M. H . , Baverman, M. M., and Hochheiser, S., Analyt. Chem., 1957, 29, 1349. Mason, D. M., Petrol. Refiner, 1964, 43, 145. Jacobs, M. R., J . A i r Pollut. Control L4ss., 1965, 15, 314. Bostriim, C. E., I n t . J . A i r W a t . Pollztt., 1966, 10, 435. Huyghen, C., Analytica Chim. ,4cta, 1964, 30, 556. Geiger, E., Nobs, H., and Halasz, P., Helv. Chim. A d a , 1959, 42, 1345. Wronski, M., Chemia Analit., 1960, 5, 457; Analyt. *-lbstr., 1961, 8, 1496. Dean, G. A., Analyst, 1966, 91, 530. Heuschkel, G., Erddl Iiokle, 1961, 14, 467; Analvt. A6str., 1962, 9, 2275. Offutt, E. R., and Sorg, I,. IJ., U.S. Patent 2,800,397, 1957. Sanderson, H. P., Thomas, A., and Katz, &I., ./. A i r Pollzd. Control Ass., 1966, 16, 328. Park, J . P., Ibid., 1966, 16, 325. Andrew, T. R., and Nichols, P. N. R., rlnalysL, 1965, 90, 367. Gilardi, E. I?., and Manganelli, K. M., .J. Azr 2’o/lz!t. Control A s s . , 1963, 13, 305. Hochheiser, S., “Methods of Measuring and Monitoring Atmospheric Sulphur Uioxidc,” U.S. Department of Health, Education and IVelfare, Public Health Service, Division of Air Pollution, 1964. Analyt. Abstr., 1961, 8, 519. LVelch, A. F., and Terry, J. P., Amer. I n d . Hjtg. .4ss. J., 1960, 21, 316. Thoenes, H. U’., Brennst.---Clzem., 1961, 42, 116. Herrmann, G., 2. Chemie, Lps., 1962, 2, 42. Thomas, 54. D., J . A i r Pollut. Control d s s . , 1964, 14, 517. Hochheiser, S., Ibid., 1966, 16, 266. Stratmann, H., and Buck, M., I n t . J . A i r W’at. Pollut., 1965, 9, 199. Urone, P., Evans, J . B., and Noyes, C. M., A4?zaZjft. Chem., 1965, 37, 1104. Huygen, C., Analytica Chim. Acla, 1963, 28, 349. Pate, J. B., Ibid., 1963, 28, 341. West, P. LV., and Gaeke, G. C., Analjit. Chem., 1966, 28, 1816. West, P. W., and Ordoveza, &.., Ibid., 1962, 34, 1324. Pate, J . R., Ibid., 1965, 37, 942. -, Ibid., 1962, 34, 1660. Helwig, H. L., and Gordon, C . L., Ibid., 1958, 30, 1810. Herrmann, G., Staub, 1965, 25, 271. Chamorro, €I. U., Salud Ocup., 1965, 10, 51. Kniseley, S. J . , and Throp, T.. J.. Analyt. Chem., 1966, 38, 1270. British Standard, B.S. 1747, Part 3 : 1963. ICenny, M. T., Warran Spring Laborator!! Hq‘~or:s LR3 and LR4, n’linistry of Terhr.olog\-, \\-arren Bracewell, J . M., and Hodgsun, A. E. hr., Int. J . A i r TL’at. Pollrit., 1965, 9, 431. Bostriim, C. E., Ibid., 1965, 9, 333. Ceausescu, L)., Kame Chim., Buc., 1965, 16, 165. Hands, G. C., and Rartlett, A. F. F., Analyst, 1960, 85, 147. 11.11. Factory Inspectorate, Ministry of Labour, “lVethods for thc Dctcction of Toxic Substances in Air,” Booklet S o . 3, Sulphide Djaxide, H.M. Stationery Ofticc, London, 1961. Kobayashi, Y., j a p a n Analyst, 1960, 9, 229; A m l j d . Abstr., 1961, 8, 4846. McConnaughey, P. U’., U.S. Patent 2,736,638, 1966; British Patent 793,727, 1958. Heuschkel, G., Erdol Kohle, 1961, 14, 467. Patterson, G. D., and Mellon, M. G., 1J.S. Patent 3,785,959, 1957. Engelhardt, II., Dechema Monogr., 1966, 54, 219. Fuhrmann, H., Staztb, 1965, 25, 266. Cummings, \V. G., and Redfearn, M. \Y., .J. Tnst. Fuel, 1957, 30, 628. Rokhoven, L., and Siessen, H. L. J., I n t . .I. A i r Wat. Pollut., 1966, 10, 233. Rassett, P. M., and Uavies, I., Ibid., 1966, 10, 633. Nash, T., ,I. Scient. Instrum., 1961, 38, 480. TJoyd, D. A., and Madden, M., Ibid., 1964, 41, 622. Nash, T., I n l . ,I. Air Wat. Pollut., 1964, 8, 121. Rerton, A., Bizdl. SOC. Chim. Fr., 1959, 10, 1453; Analyt. Abstr., 1960, 7, 2610. Xovak, J. V. A., British Patent 899,059, 1959. Spring Laboratory, Stevenage, Hcrts., 1965.758 692. 693. 694. 695. 696. 697. 698. 699. 700. 701. 702. 703. 704. 705. 706. 707. 708. 709. 710. 711. 7 12. WILSON AND DUFF Sulphz~r, 1965, No. 56, 29. Rarendrecht, E., and Martens, W., Analyt. Chem., 1962, 34, 138. Bersin, R. L., Brovsaides, F. J., and Hommel, C. O., J . A i r Pollut. Codrol Ass., 1962, 12, 129. Ross, H. H., and Lyon, W. S., Nucl. Sci. Abstr., 1965, 19, 5039. Duckworth, S., Levaggi, D., and Lim, J., J . A i r Pollut. Control Ass., 1963, 13, 429. Kuczynski, E. R., Ibid., 1963, 13, 435. Jutze, G. A., and Lewis, K. J., Ibid., 1965, 15, 323. British Standard, B.S. 1747, Part 4 : 1963. Thomas, M. D., J . A i r Pollut. Control Ass., 1961, 11, 24. Rowden, S. R., I n t . J . A i r Wat. Pollut., 1964, 8, 101. Hickey, H. R., and Hendrikson, E. R., J . A i r Pollut. Control Ass., 1965, 15, 409. Huygen, C., Mikrochim. Acta, 1963, 6. Rlinn, R. C., and Gunthcr, F. A, Analyst, 1961, 86, 675. “Methods of Measuring Air Pollution,” O.E.C.D., Paris, 1964, p. 56. Commins, B. T., Analyst, 1963, 88, 364. Scaringelli, F. P., Boonc, R. E., and Jutze, G. A., J . A i r Pollut. Control Ass., 1966, 16, 310. Peregud, E. A., Stepapenko, E. S., and Bo’lkina, B. S., Zh. Analit. Chim., 1962, 17, 770; Analyt. Kanno, S., I d . J . A i r Wat. Pollut., 1959, 1, 231. Zurlo, N., hledna Lav., 1962, 53, 325; Chem. Abstr., 1963, 58, 7290f. Wilson, C. L., and Wilson, D. W., Editors, “Comprehensive Analytical Chemistry,” Volume 1 A , Elsevier Publishing Co., Amsterdam, London, New York and Princeton, 1959, p. 283. H.M. Factory Jnspectorate, Ministry of Labour, “Methods for the Detection of Toxic Substances in Air, Booklrt No. 4, Benzene, Toluene and Xylene, Styrene,” H.M. Stationery Office, London, 1966. Received January 2nd, 1967 Abstr., 1963, 10, 2929.

ISSN:0003-2654    

DOI:10.1039/AN9679200723

出版商:RSC    

年代:1967

数据来源: RSC

摘要:

Analyst, December, 1967, Vol. 92, $p. 759-762 759 Some Observations on the Determination of Mercury by Atomic-absorption Spectroscopy in an Air = Acetylene Flame BY D. N. HINGLE, G. F. KIRKBRIGHT AND T. S. WEST (Chemistry Department, Imperial College, London, S. W.7) The sensitivity obtained for mercury a t 2537 in atomic-absorption spectroscopy in air - acetylene is greatly influenced by the valency state of mercury in the sample solution. Greater sensitivity is obtained for mercury(1) than for mercury(II), and further increase in sensitivity results when reducing and complexing agents are added to mercury(1) solutions. An explanation of this effect based on the disproportionation of mercury(1) into mercury(I1) and elemental mercury is given. THE determination of mercury by atomic-absorption spectroscopy in conventional flames has a rather limited sensitivity.During a study of the determination of mercury and several other elements in a long-path separated air - acetylene flame,l we observed that the sensitivity was greatly influenced by the valency state of the mercury introduced into the flame. These observations, with a relatively unusual (i.e., separated) flame, led us to pursue the investi- gation of this phenomenon in a conventional 10-cm air - acetylene flame of the type available on most commercial atomic-absorption spectrophotometers. Mie have found, as reported elsewhere,2 that an enhancement of the sensitivity is obtainable when mercury is presented to the flame as mercury(1) rather than mercury(II), and also that the addition of reducing or complexing agents to the mercury sample solutions can result in an even greater increase in the absorbance for mercury at 2537 A.The results of these experiments are described in this paper. EXPERIMENTAL APPARATUS- Techtron AA4 flame spectrophotometer and 10-cm air - acetylene burner. The source of resonance radiation used was a microwave-excited mercury-discharge tube as described elsewhere.1 The instrument settings used throughout were : slit width, 50 p ; wavelength, 2537 A ; air pressure, 15 p.s.i.; acetylene flow-rate, 2-5 litrcs per minute. The microwave power output from 2450 Mc/s generator to discharge tube was 7 watts. REAGENTS- ,411 materials should be of analytical-reagent grade. Merczuy(1) stock solz~tio~z--r)issolve 0.140 g of mercury(1) nitrate, Hg,(h-O,) ,.2H,O, in 0.5 M nitric acid and dilute to 100 ml with 0.5 11 nitric acid.Store over a small amount of metallic mercury. Mercury(I1)) stock solution-Dissolve 0-1708 g of mercury(I1) nitrate, Hg(N0,) ,.2H20, in 0.5 M nitric acid and dilute to 100 ml with 0.5 M nitric acid. Dilute this 1000 p p m . stock solution as required. Ascorbic acid. Tin(II) chloride. EDTA (disodium salt). Citric acid. Tartaric acid. Potassiwm cyaqzide. Gelati.;1a. Dilute this 1000 p.p.m. stock solution as required.760 HIKGLE, KIRKBRIGHT AND WEST [Analyst, Vol. 92 RE su LTS The optimum conditions of slit width, fuel flow-rate and microwave discharge-tube power were established for the determination of mercury at 2537 A. The absorbance produced under these conditions for 40 p.p.m.of rnercury(1) and rnercury(I1) nitrate solutions was recorded in the presence, and absence, of excess of ascorbic acid, tin(I1) chloride, EDTA, citric acid, tartaric acid, potassium cyanide and gelatin. Care was taken to establish blank absorbance values for each solution nebulised. The results obtained are shown in Table I. TABLE I EFFECT OF REDUCING AND COMPLEXING AGENTS ON ABSORPTIOPI; BY MERCURY AT 2537 A Sample solution containing 40 p.p.m. of mercury Hg(W Hg(I) 7 f -7 r-p-A-p_-- S e t mercury Net mercury absorbance a t absorbance a t 2537 A* 2537 A* + Nitric acid, 0.5 hi . . . . . . 0.010 + Nitric acid, 0.5 XI . . . . , . 0.040 + EDTA (disodium salt), 5 mg per ml 0.108 + Ascorbic acid, 5 mg per ml . . 0.163 + Ascorbic acid, 5 mg per ml .. 0.160 + Tin(I1) chloride, 5 mg per ml . . 0.160 + Tin(I1) chloride, 5 mg per ml . . 0.160 + Citric acid, 5 mg pcr In1 . . . . 0.012 + Citric acid, 5 mg per ml . . . . 0.062 + Tartaric acid, 5 mg per ml . . 0.012 -t Tartaric acid, 5 mg per ml . . 0.047 + Potassium cyanide, 5 mg per nil 0.010 * These values were obtained a t a constant burner height above the primary zone in the flame. 0.01 1 -+ EDTA (disodium salt), 5 mg per ml 0.012 + Potassium cyanide, 5 mg per ml In order to assist the interpretation of these results, the variation in absorbance for mercury at 2537 with height in the flame was investigated during aspiration of solutions of mercury(1) and mercury( 11) nitrates, and of mercury(I1) nitrate immediately after the addition of excess of ascorbic acid solution.The corresponding absorption profiles are shown in Fig. 1. The absorbance growth curves in the flame for mercury(I), mercury(I1) and mercury(I1) - ascorbic acid solutions were also obtained at the height in the flame of maximum absorbance for these solutions. These calibration curves are shown in Fig. 2. Fig. 1. Variation of absorbance at 2637 .‘i with position of light-path above burner head for mercury(1) (10 p.p.m.), mercury (11) (260 p.p.m.) and a mercury(I1) solution (20 p.p.m.1 con- taining 5 mg per ml of ascorbic acidDecember, 19671 OBSERVATIONS ON THE DETERMINATION OF MERCURY 761 Mercury, p.p.m Fig. 2. Absorbance growth curvcs for mercury(I), and mer- cury(I1) solutions and mercury(I1) solutions containing 5 mg per ml of ascorbic acid.These graphs were obtained at the optimum burner height for each solution The results shown in Table I can be explained by consideration of the unique property of the mercury( I) ion, HgZ2+, whereby it disproportionates readily to form the mercury( 11) ion and free elemental mercury Hgz2+ ---+ Hg2+ + HgO. When mercury(1) solutions are nebulised this reaction proceeds to some extent as the sample mist passes into the pre-heating zone of the burner. Consequently a partial pressure of elemental mercury vapour is available very low in the flame. This effect is much less marked with mercury(I1) solutions. The addition of excess of ascorbic acid or tin(I1) chloride solution to either mercury(1) or mercury(I1) nitrate solutions results in complete reduction of the mercury to the elemental form in the dilute solution so that an enhancement from this effect is observed.The sample solution then contains the mercury in colloidal elemental form. The addition of EDTA to mercury( I) solutions promotes the disproportionation by formation of a strong complex with the mercury(I1) ion. Thus the effect of EDTA is to enhance the absorbance by promotion of the liberation of elemental mercury. As shown in Table I, the addition of EDTA to mercury(J.1) nitrate solution has no significant effect on the absorbance. As even the complete disproportionation of the mercury(1) ion by EDTA only results in liberation of half of the mercury as the element, by the reaction it would be expected that, at most, EDTA could only produce half of the enhancement in absorbance provided by cotnplete reduction with ascorbic acid or tin(1T) chloride.This is true to a first approximation, as shown in Table I . The failure of citric and tartaric acids to enhance the absorbance significantly may result from the fact that mercury(I1) does not form stable citrate and tartrate complexes at the acidity used. Potassium cyanide also causes no enhancement of the absorbance. Indeed, addition of potassium cjmide to mercury( I) solutions results in an absorbance characteristic of the same concentration of niercury(I1). It is probable that the elemental mercury formed by the disproportionation is re-dissolved in the nitric acid - potassium cyanide medium to form the stable mercury(I1) cyanide complex Hg(CN),2-. The manner in which the absorbance at 2537 A varies with height in the flame for the introduction of mercury( I), mercury( 11) and colloidal elemental mercury also supports the explanation suggested.Tt may be seen from Fig. 1 that once the mercury passes the primary zone of the air - acetylene flame, little decrease in absorbance with height is observed, regardless of the form in which the mercury is introduced into the flame. Thus little depletion of the ground-state atomic population appears to occur as the temperature decreases and the flame plasma becomes more oxidising in nature. This would be expected, as the reaction HgZ2+ + H2EDTA2- -+ Hg(1T)EDTA'- + Hgo + 2H+,762 HINGLE, KIRKBRIGHT AND WEST HgO -+ Hg +- 0 favours elemental mercury above about 500" C. Thus the increaed sensitivity that results from the introduction of the sample as mercury(I), or elemental mercury, is preserved well above the primary zone. The absorption - height profiles low in the flame (including those within the primary zone) are also of interest.Thus when a mercury(I1) solution is nebulised, maximum absorbance is not obtained until slightly above the primary zone in the hottest part of the flame. This can be explained by the need for a relatively high temperature (above 500" C) to decompose mercury(I1) nitrate and mercury(I1) oxide clotlets efficiently. When elemental mercury is introduced, however, maximum absorb- ance is observed immediately above the burner-plate within the primary zone (in the pre-heating zone, in fact). The decrease in absorbance with height in the pre-heating zone behind the flame front may possibly be explained by the expansion of the sample -gas mixture as the temperature rises with height throughout this zone.This causes a dilution of the sample as the gas mixture expands. Fig. 2 shows the absorbance growth curves obtained for mercury(I), mercury(I1) and elemental mercury. The cause of the non-linearity is difficult to explain unequivocally, and may be caused by either pressure broadening of the mercury-line profile in the flame, or by some reversal in the mercury microwave discharge source. The possibility of curvature of absorbance growth curves because of fluorescence emission when high intensity sources are used has already been noted el~ewhere.~ Because of the non-linearity, even at low absorbances, we suspected that the intense emission of the 2537 A line from the microwave-excited source was producing significant resonance fluorescence of the 2537 A line in the flame, thus diminishing the expected absorbance signal.Experiments in which the spectrometer is placed at 90" to the optical axis of the 10-cm flame and excitation source reveal that although significant fluorescence is emitted, because of the focusing arrangement used, this contributed little to the 2537 A radiation reaching the narrow monochromator entrance slit. I t must be noted that, while pre-treatment of mercury sample solutions with excess of reducing agents leads to considerably increased sensitivity, the absorbance thus produced is rather dependent on ageing of the solution following addition of the reductant.This results from the rapid aggregation of the finely dispersed nuclei that are initially formed. The use of gelatin in an attempt to stabilise the mercury sol is ineffective in the presence of ascorbic acid and tin(I1) chloride. The stability of the mercury(1) - EDTA solution is improved, however, possibly because EDTA has less tendency to flocculate the colloidal element. The sensitivity of the determination of traces of mercury by atomic-absorption spectro- scopy may thus be increased four-fold by introduction of the sample as mercury(1) rather than mercury(I1). Treatment of mercury(I1) solutions with excess of reductant results in about a sixteen-fold enhancement in sensitivity, but, in order to obtain good repeatability, the absorbance at 2537 A must be measured immediately after addition of the ascorbic acid or tin(I1) chloride solution. Similarly the treatment of a mercury(1) solution with excess of reductant provides a four-fold enhancement for this ion. ,4s stated previously, the unusual dependence of absorbance signal on valency state is not observed with most other multivalent elements and arises for mercury because of the unusual nature of the mercury(1) ion. We are grateful to Murex Ltd. for provision of study leave to one of us (D.N.H.), and for the loan of the flame spectrophotometer used in this work. These calibrations are repeatable but non-linear. REFERENCES 1. 2. 3. Hingle, D. N., Kirkbright, G. F., and West, T. S., Talanta, 1968, 15, in the press. Handbook, Techtron AA4 Spectrophotorneter, Techtron Pty. Ltd., Melbourne, Australia. West, T. S., in Meinke, W. W., and Scribner, B. F., Editors, "Trace Characterization," National Received .July 12th, 1967 Bureau of Standards Monograph No. 100, Washington, 1967, p. 285.

ISSN:0003-2654    

DOI:10.1039/AN9679200759

出版商:RSC    

年代:1967

数据来源: RSC

摘要:

Analyst, December, 1967, Vol. 92, $9. 763-765 763 The Determination of Vanadium in Silicate Rocks and Minerals with N-Benzoyl -o- tolylhydroxylamine BY P. G. JEFFERY AND G. 0. KERR (Warren Sfiring Laboratory, Ministry of Technology, Stevenage, Hertfordshire) In 4 to 8 N hydrochloric acid, N-benzoyl-o-tolylhydroxylamine is an almost specific reagent for vanadium, and can be used in the analysis of rocks and minerals. After removal of silica by evaporation with hydrofluoric acid, the insoluble residue is fused with potassium pyrosulphate and dissolved in dilute sulphuric acid. The violet-coloured complex with the reagent is formed in 6 N hydrochloric acid solution, extracted into carbon tetrachloride and measured at 510 mp. Fluoride addition prevents interference from titanium, while the use of PTFE and silica apparatus avoids contamination and interference from platinum.IN the course of a recent investigation of supposed vanadium poisoning, i t was necessary to devise a reliable, sensitive and specific procedure for the determination of vanadium in urine. Rockhold and Talvitiel have devised a test for vanadium based on the catalytic oxidation of P-aminodiethylaniline. This test is used for screening purposes and is not specific for vanadium. Sandel12 describes a method with 8-hydroxyquinoline, based upon other work by T a l ~ i t i e , ~ but this procedure is long, tedious and subject to interference from several elements. A literature search showed that, although a wide variety of reagents had been advocated for the determination of vanadium in pure solutions, few of the methods based upon them were easily or directly applicable to urine.N-Cinnamoyl-N-phenylhydroxylamine has been recommended4 as a sensitive reagent, but is not specific for vanadium. N-Benzoyl-N-phenylhydroxylamine is more ~elective,~ but also reacts with molybdenum, titanium and zirconium to give yellow-to-orange coloured complexes6 that interfere with the determination of small amounts of vanadium. Benzoyl-o-tolylhydroxylamine seemed to us to combine the necessary sensitivity and specificity to vanadium, but we were unable to obtain reliable results by the procedure described by Majumdar and Das7 After suitable modification, the procedure has been found to be acceptable for the determination of vanadium in urine. These modifications have also enabled the reagent to be applied to the determination of vanadium in silicate rocks and minerals.The procedure devised for this is applicable to silicate materials containing from a few parts per million of vanadium to parts per thousand, or more. It is considerably more rapid than the procedure formerly used in this laboratory, which is based on a chloroform extraction of the complex with 8-hydroxyquinoline, followed by photometric measurement as phosphovanadot ungst at e. EXPERIMENTAL PREPARATIOK OF THE REAGENT- The reagent N-benzoyl-o-tolylhydroxylamine was obtained by following the directions given by Majumdar and Das.7 The yield (half quantities) was 7.5 g, or about 15 per cent. This poor yield was attributed to the excessive formation of reduction products other than tolylhydroxylamine, particularly o-toluidine.No improvement was obtained by using the method of reduction described in detail by Cohen* for the preparation of phenylhydroxyl- amine, but a significantly lower yield was obtained by the procedure described by V0ge1.~ REACTION w ITH VANADIUM- Although Majumdar and Das prepared their vanadium extracts from a vanadate solution, it is not clear from either their original7 or a laterlo paper that the reaction with vanadium764 JEFFERY AND KERR : DETERMINATION OF [Analyst, Vol. 92 does not take place unless it is in the quinquivalent state. It was noted that somewhat lower calibration graphs were obtained when aliquots of standard vanadate solution were not re-oxidised prior to react ion with ili- benzo yl-0- t olylh ydroxylamine.This was added drop by drop until the pink reagent colour persisted for 5 minutes. The slight excess was decomposed by adding hydrochloric acid, and any chlorine liberated was removed by adding sulphamic acid. It is therefore slightly more sensitive than A-benzoyl-A'-phenylhydroxylamine ( E = 4650) and less sensitive than iV-cinnamoy1-A7-phenylhydroxylamine ( E = 6300) .4 For this oxidation an aqueous solution of potassium permanganate was used. The molar extinction coefficient for the o-tolyl reagent was found to be 5250. IXTERFERl<NCES- The most serious interference noted by us in the determination of vanadium in silicate materials is from the intense yellow-coloured complex formed by the reagent with titanium.In all the samples examined by us, this colour was completely suppressed by the addition of a small amount of saturated sodium fluoride solution. The reagent also gives yellow colours, not previously recorded, with gold and platinum. The small amounts of gold and platinum that occur in silicate rocks are insufficient to interfere with the determination of vanadium, although platinum introduced following a pyrosulphate fusion in platinum apparatus will completely obscure the violet colour from rocks containing only a few p.p.m. of vanadium. For this reason prolonged fusion in platinum apparatus should be avoided, and the alternative decomposition in PTFE and silica used, particularly for samples low in vanadium. EXTRACTION OF THE VAXADILJM COMPLEX- The complex formed between vanadium and N-benzoyl-o-tolylhydroxylamine is soluble in several organic solvents.Solutions in carbon tetrachloride, chloroform, isobutyl methyl ketone and toluene all gave similar calibration graphs. Chloroform was rejected because of possible interference from the presence of ethanol, which gives rise to a yellow coloured complex of vanadium with the reagent. Carbon tetrachloride was finally selected, being more convenient to use than the lighter solvents. METH o D REAGENTS- 100 ml of carbon tetrachloride. N-BeizzoyZ-o-toZyZhydro~uyZamiize soZutioiz-Dissolve 0.02 g of the recrystallised reagent in Potassium permanganate solution-Approximatelv 0.02 M , Sulphamic acid solution-Approximately 0-05 hi. Sodiuw juoride soZzitio?z-Saturated solution in water.PROCE T) I: RE- Decompose a 100-mg portion of the finely powdered silicate material by evaporating it in platinum (or PTFE apparatus for samples low in vanadium) with sulpliuric, nitric &id hydrofluoric acids in the usual way, removing excess sulphuric acid by heating on a hot-plate. Fuse the dry residue in platinum, or preferably silica, with potassium pyrosulpliate and extract the fused melt with 10 nil of water containing 2 drops of 20 x sulpliuric acid. Transfer the solution to a separating funnel and add potassium permanganate solution drop by drop until an excess giving a pink colour that persists for 5 minutes is present. The volume of the solution at this stage should be about 20 ml. Add 2 ml of sulphamic acid solution, 2 ml of sodium fluoride solution and 20 ml of concentrated hydrochloric acid.Now add by pipette 10 ml of the N-benzoyl-o-tolylhydroxylamine solution, stopper and shake the funnel for 30 seconds. Allow the layers to separate and filter the lower layer through a small wad of cotton-wool into a 2-cm spectrophotometer cell. Measure the optical density of this solution, relative to a reagent blank, at a wavelength of 510mp. For the calibration graph, transfer aliquots of a standard vanadate solution containing 10 to 5Opg of vanadium to a series of separating funnels and dilute each to 20 ml. Add potassium permanganate solution drop by drop to each until an excess is present, and continue as described for the sample solution above. Store in a polythene bottle.December, 19671 VANADIUM I N SILICATE ROCKS AND MINERALS 765 RESULTS This procedure has been used to determine vanadium in a wide variety of silicate materials. The results obtained for a series of standard rocks are given in Table I.One sample (GSP-1) was analysed ten times, giving an average value of 43 p.p.m. of vanadium, a standard deviation of 1.7 p.p.m. and a coefficient of variation of 4 per cent. Sample No. TABLE I A COMPARISON OF RESIJLTS FOR SOME SILICATE ROCKS Description and locality 0- Vanadium, p.p.m. A 7 7 N-Benzoyl- Other reported .tolylh ydroxylamine results G-1 Granite, Rhode Island, U.S.A. . . . . . . 13, 15, 15, 16 16* G-2 Granite, Rhode Island, U.S.A. . . . . . . 28, 30, 34, 34 37t (18) W-1 Diabase, Virginia, U.S.A. . . . . . . . . 240, 222, 266, 234 240* T-1 Tonalite, Msusule, Tanzania .. . . . . . . 81, 77, 83, 81 96; R117 Granite, Shetland, U.K. . . . . . . . . 2, 3, 2 6s R204 Nepheline-syenite, Khibina, I,..S.S.R. . . . . 42, 46, 48, 49 - AGV-1 Andesite, Oregon, lJ.S.A. . . . . . . . . 100, 104, 109 134t (18) PCC-1 Peridotite, California, [J.S.A. . . . . . . 30, 24, 24 29t (18) DTS-1 Dunite, Washington, U.S.A. . . . . . . . . 10,10,12 1lt (15) GSP-1 Granodiorite, Colorado, U.S.A. . . . . . . 45, 41, 41, 46, 42 53t (18) BCR-1 Basalt, Washington-Oregon, U.S.A. . . . . 315, 398, 396 3397 (18) 45, 42, 43, 43, 42 * Ahrens and Fleischer,ll “recommended values.’’ t Flanagan,’Z “average of spectrochemical determinations” (with number of determinations). 1 Average of reported re~u1ts.l~ $ Result obtained previously by mcthod of Bennett and Pi~1rup.I~ 1.2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. REFEREXCES Rockhold, W. T., and Talvitie, K. A., Clin. Chew., 1956, 2, 188. Sandell, E. B., “Colorimetric 13etermination of Traces of Metals,” Third Edition, Interscience Publishers Inc., New York and London, 1959, p. 939. Talvitie, N. A., Analyt. Chcm., 1953, 25, 604. Priyadarshini, U., and Tandon, S. G., Analyst, 1961, 86, 544. Ryan, D. E., Ibid., 1960, 85, 569. Priyadarshini, U., and Tandon, S. G., Analyt. Chem., 1961, 33, 435. Majumdar, A. K., and Das, G., .4nalytzca Chzm. Acta, 1964, 31, 147. Cohen, J. B., “Practical Organic Chemistry,” Third Edition, Macmillan, London, 1924, p. 164. Vogel, A. I., “Practical Organic Chemistry,” First Edition, Longmans, Grcen & Co., London, Majumdar, A. K., and Das, G., Analytica Chim. Acta, 1966, 36, 464. Ahrens, L. H., and Fleischer, M., U.S. Geol. Surv. Bull., 1960, No. 1113, 101. Flanagan, F. J., Geochim. Cosmochim. Acta, 1967, 31, 289. Thomas, \Ir. K. I.., “Standard Geochemical Sample I-1,” Msusule Tonalite, Supplement No. 1, Rennctt, IV. H., and Yicltup, K., Colon. Geol. Minev. l?eso?rr., 1952, 3, 171. 1948, p. 602. Government Printer, I k r es Salaam, 1963. Received J u l v 6th, 1967

ISSN:0003-2654    

DOI:10.1039/AN9679200763

出版商:RSC    

年代:1967

数据来源: RSC

摘要:

766 Analyst, December, 1967, Vol. 92, p p . 766-768 Isotopic-dilution Analysis with a Modified Substoicheiometric Residue Method for Carbonate and BY J. I(. JOHANNESSON ( A uckland T e c h ical Institute, Wellesley Street, Auckland, New Zealand) 14 new modification of the substoicheiometric isotopic-dilution method is presented. After the addition of a standard amount of labelled compound, the isotopically diluted compound is then isolated, as a residue of constant weight, and the beta activity measured. The method applied to the deter- mination of sulphate and carbonate is applicable in the range 10 to 100,uug for these anions. ISOTOPIC-DILUTION methods based on the use of substoicheiometry have been reviewed by Lambie,l who outlined the three methods that had been published at that time.Firstly, the use of a deficiency of the complexing agent for solvent extraction of the isotopically diluted substance into water-immiscible solvents, as developed by RuiiCka and Starq., Secondly, the decomposition of equal weights of metal by the passage of equal amounts of electrical current, also by RtiiiCka.3 Thirdly, the method used by the present a ~ t h o r , ~ where equal amounts of an isotopically diluted element are precipitated by using a constant amount of a precipitant, which amount is, however, less than that required to precipitate all of the element being determined. The particular method described was the determination of chloride with a substoicheiometric amount of silver as the precipitant. This paper presents a fourth method whereby a constant weight of a compound, of the substance to be determined, is left as a residue of constant weight following volatilisation of the excess of substance over the substoicheiometric amount.Two variations of this method are described, one for the determination of sulphate and the other for the determination of the carbonate. DETERMINATION OF SULPHATE an sol The principle of this method is that the test solution is first passed through a column of ion-exchange resin, in the hydrogen form, to convert any salts to free acids, and to this ution is added a known amount of dilute sulphuric acid labelled with sulphur-35, followed by a known amount of standard barium nitrate solution, insufficient to combine with all of the added labelled sulphuric acid.The mixture is evaporated in a suitable container, which also acts as the mount for counting. Volatile acids and excess of sulphuric acid are volatilised, lqaving a constant weight of bariutn sulphate, the beta activity of which is then determined under a thin end-window Geiger - Miiller counter. The method has the advantage of constant weight for counting, and thus no allowance has to be made for self-absorption. Non-volatile acids such as silicic and orthophosphoric acids interfere, whereas acids such as hydrochloric, nitric, acetic and other organic acids are readily volatilised under the experi- ment a1 conditions. The calculation is as follows- w, = w, ($ - 1.0) where W , is the weight of the unknown sulphate ion, Wz is the weight of the added sulphur-35 labelled sulphuric acid, A , is the activity in counts per minute when only the labelled sulphuric acid was A , is the activity in counts per minute found when an unknown amount of sulphate present and was being determined.J OHANNESSON 767 APPARATUS- at the top and 1 cm diameter at the base.PROCEDURE- To the solution containing 10 to 15pg of sulphuric acid add 1-00 ml of 0-001 R.I sul- phuric acid labelled with sulphur-35, and, after careful and complete mixing in the crucible with a jet of air playing on to the surface of the liquid, add 1-00 ml of 0-0004 M barium nitrate solution, again with careful mixing. Evaporate the contents of the crucible to dryness under an infrared drying lamp, then ignite at a dull red heat for exactly half a minute. The crucible is supported in a frame and the Geiger - Miiller counter inserted to within a fixed distance from the bottom of the crucible and the beta radiation measured.The time taken for a count of ten thousand is accurately determined and it is found that the repeatability is within the statistical limits of plus or minzts twice the standard deviation for the counting, even when the crucible is removed and returned to the frame between successive counts. Thus, the times for a repeat count to ten thousand, with removal and replacement of the crucible in the frame are 17-85 and 17.60 minutes, respectively. ,4 typical series of results for a set of known sulphuric acid samples is as shown in Table I. Porcelain crucibles-These should be of uniform size, i.e., 2 cm high with a 2.5 cm diameter TABLE I APPLICATION OF THE METHOD TO THE DETERMINATIOK OF SULPHATE Sulphuric acid added, Counts per minute Sulphuric acid found, Error, Crg (corrected for background) Crg per cent.25 616 24 -4 50 496 53 + 6 75 439 73 -3 150 313 142 -6 - - 0 7 60 The standard deviation for the accuracy of counting for this set of results was 2 per cent. THE EFFECT OF IGNITION TIME- There is need for ignition because of the apparent formation of some barium hydrogen sulphate that is not decomposed by use of the heating lamp alone. If ignition times are prolonged, then loss of activity occurs as shown. The time for ignition must be kept short or a loss of activity occurs. Time of heating a t red heat, minutes . . .. 0.5 5 15 45 85 Counts per minute . . . . .. . . 803 645 590 500 435 For the amounts of sulphate taken the accuracy attained is comparable with other analytical methods, especially in the presence of other acids.Improvement of this method will require investigation of the techniques of heating to decompose the barium hydrogen sulphate, without any decomposition of the barium sulphate. DETERMINATION OF CARBOXATE The method for the determination of carbonate involves the addition of a constant amount of carbonate, labelled with carbon-14, to the sample which has been made sufficiently alkaline to prevent loss of carbon dioxide to the air, but not so alkaline as to absorb it rapidly from the air (pH = 8 is about the optimum). To the well mixed solution is added hydrochloric acid (1 + 4), the liberated gas is absorbed in a small volume of a solution of barium hydroxide, such that the weight of this latter substance, and hence of the barium carbonate formed, is constant.Further, the stoicheiometric amount of barium hydroxide added is equal to about half of the added labelled carbonate, In this way a constant amount of carbon dioxide is absorbed in each determination. The activity of the dried barium carbonate is counted by using a thin end-window Geiger - Muller tube and, as discussed under the sulphate method, the constant weight of the source eliminates the errors and corrections needed when self- absorption has to be considered. The method of calculation is the same as for the sulphate method.768 J OHANNESSOX The initial experiments were made with an apparatus in which the unknown and labelled carbonate solutions were mixed in a reaction vessel, acidified, and the evolved carbon dioxide aspirated through a solution of barium hydroxide contained in an absorption tube.The suspension of barium carbonate was transferred to a planchet, evaporated, and the activity measured. This method was found unsatisfactory in that losses of barium carbonate occurred from adhesion to the sides of the absorption tube. The necessary use of wash water to effect transfer of the suspension required that the planchet be re-filled several times, thus giving an unsatisfactory distribution of the powder. The method finally decided on involved the use of the Conway diffusion apparatus, with a stainless-steel planchet in the central compartment containing a small amount of aqueous barium hydroxide in the form of a drop of constant volume in the centre of the planchet.In this way, the carbon dioxide liberated from the outer reaction compartment was absorbed directly into the barium hydroxide solution in the planchet. This was then dried and counted, thus eliminating the need to transfer the barium carbonate that had been formed. By adding, accurately, 0.100 ml of standard barium hydroxide to the centre of the planchet, the final barium carbonate of constant weight was obtained as a thin film over a small central area of the planchet, thus giving good geometry for counting. PROCEDURE- Place 1 nd of the sample to be analysed, containing between 10 and 400 pg of car- bonate, in the outer compartment of the Conway cell.Add 1.00ml of the labelled 0.01 x sodium carbonate and mix the solutions carefully by gentle swirling. Prepare the labelled sodium carbonate solution by adding 1.0 ml of 0-003 N sodium carbonate, with an activity of 10 microcuries, to a 100-ml graduated flask, followed by 10.0 ml of 0.10 N sodium carbonate and then make up to the mark with water. Transfer, by micropipette, a 0.10-ml aliquot of 0-04 N barium hydroxide solution on to the centre of a stainless-steel planchet, then quickly transfer it to the central compartment of the Conway unit and place the cover on without delay. Slide the cover slightly to one side to allow the addition of 1 ml of hydrochloric acid (1 + 4) and replace the lid, then swirl the unit gently and allow to stand for several hours. At the end of this time open the unit, dry under a drying lamp, and count the activity. A typical set of results is given in Table 11. TABLE I1 1 4 ~ ~ ~ ~ ~ ~ OF THE METHOD TO THE DETERMINATIOK OF CARBONATE Carbonate, as pg of CO, Counts per minute Carbonate, as pg of CO, Error, taken (corrected for backgroiind) found per cent. - 0 1518 0 55 1205 51 - 8 110 1006 106 -4 220 715 240 + 9 The standard deviation for the activity counting was 2 per cent. This paper demonstrates the use of the residue modification of the substoiclieiometric method for isotopic-dilution analysis. The examples given above show accuracies comparable with other analytical methods for the range of concentrations and absolute amounts present. REFEREKCIS 1 . 2. 3. 4. Lambie, D. A . , “Techniques for the Use of Radioisotopes in Analysis,” E. and E’. N. Spon Ltd., RGiiCka, J., and Starq, J., Talanta, 1961, 8, 228. RbiiEka, J . , Colln Czech, Chem. Comnzun., Engl. E d n , 1960, 25, 199. Johannesson, J. I<., Analyst, 1961, 86, 72. London, 1964, p. 10. Reccivcd July 27t12, 1967

ISSN:0003-2654    

DOI:10.1039/AN9679200766

出版商:RSC    

年代:1967

数据来源: RSC

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Analyst, December, 1967, Vol. 92, $9. 769-772 769 A Radiochemical Separation Technique for Palladium BY G. G. J. BOSWELL AND T. McGEE (University of Salford, Salford 5, Lancashire) The solvent extraction of palladium acetylacetonate with benzene was studied and shown to be a rapid, efficient and selective method for the radiochemical separation of palladium from fission and spallation products. The yield of the palladium was 90 per cent. in the absence of chloride ions, and the radiochemical purity was shown to be good. THE majority of radiochemical separation techniques reported for palladium1 depend on the formation of the dimethylgloxime complex. These methods involve lengthy procedures to remove silver contamination. The work in our laboratory required a rapid and simple method that would separate palladium, radiochemically pure, especially from silver.I t was decided to investigate a solvent-extraction procedure based on the pH dependence of metals extracted as the acetylacetonate. The use of acetylacetone as a chelating agent and its application to solvent extraction have been reviewed.2 Star$ and Hlz~dkS;~ have determined the extraction constants for the extraction of thirty metals by acetylacetone, from which the optiniuin separation conditions for palladium can be predicted. EXPERIMEKTAL The method was developed with radioactive palladium-103 as a tracer. The effective- ness of decontamination from neiglibouring elements was tested with molybdenum-99, technetium-99, ruthenium-106, rhodium-106, silver-1 10, cadmium-109 and indium-114. All of the isotopes except technetium-99 emitted gamma radiations or high energy beta radiations and were detected on an Ekco 1-75-inch diameter by 2-inch sodium iodide - thallium well scintillation counter (well volume 5 ml), and on a 3 by 3-inch sodium iodide - thallium crystal coupled to a Laben 512 multichannel analyser.The decay of the palladium isotopes was followed on a Kuclear Enterprises Gamma-Matic scintillation spectrometer; the scintillator was a well-type 3 by 3-inch sodium iodide - thallium crystal with a well volume of 12 ml. Technetium-99, which decays with low energy beta radiations, was counted on a Panax thin end-window Geiger - Muller counter. The samples for the Gamma-Matic were counted in 5-ml screw-topped glass vials. Samples counted on the Ekco well crystal were placed in 2-ml polythene vials.Technetium-99 solutions were evaporated to dryness on 1-inch dimpled planchets before being counted on the Panax end-window Geiger - Miiller counter. The phases were equilibrated by stirring with an Electrothermal mini-stirrer, and pH adjustments were made with a Pye Dynacap pH meter. REAGESTS- The radioisotopic tracers were obtained from the Radiochemical Centre, Amersham. The fission product mixture was obtained by irradiating U,08 in tlie Mancliester and Liverpool ITniversities’ Research Reactor. The palladium carrier was prepared by evaporating to dryness a solution containing a known amount of palladium(I1) chloride with concentrated nitric acid, until all of the chloride was removed.The residue was taken into solution with concentrated sulphuric acid, and the pH was adjusted to zero (with sulpliuric acid - sodium hydroxide). The solution was diluted with sulphuric acid (pH = 0) so that it contained 0.5 mg of palladium per ml of solution. “Holdback” carriers were not used in our experiments as we were developing tlie method for general use, but if required they should be added before the evaporation stage in the procedure. All reagents used were of analytical-reagent grade.770 BOSWELL AND MCGEE : A RADIOCHEMICAL [AutaZyst, Vol. 92 PROCEDURE- Add 0.5 mg of inactive palladium carrier to the sample solution (add holdback carriers if required). If chloride ions are likely to be present, evaporate the solution to dryness with nitric acid until a test for chloride is negative. Dissolve the residue in sulphuric acid and adjust the pH to 0 with sulphuric acid and sodium hydroxide.Mask any interference caused by the presence of molybdenum by adding 0 6 m l of 30 per cent. v/v hydrogen peroxide4 to the solution. Equilibrate 5 ml of this solution with an equal volume of 0.1 M acetylacetone in benzene by mechanically stirring the phases for 5 minutes in a 50-ml centrifuge tube. Separate the phases by centrifugation and wash the organic phase with 5ml of sulphuric acid (pH = 0) for 30 seconds. Separate the phases and withdraw 2 ml of the acetylacetone layer for counting. RESULTS AND DISCUSSION The time required to reach extraction equilibrium was investigated by determining the count-rate of 2 ml of the acetylacetone phase, obtained by intimately mixing 5 ml of 0-1 M acetylacetone in benzene, for different times with 5 ml of a sulphuric acid solution (pH = 0) containing 0.5 mg of palladium carrier and equal amounts of palladium tracer.Fig. 1 shows 4o.Ooo u C U a 30.000 E .- L 0) a v) 2 20,000 3 s I O.Oo0 Time, minutes Fig. 1. Time required to reach extraction equilibrium in the extraction of palladium with acetylacetone in benzene the activity of the extracts plotted against the time of stirring. Equilibrium conditions are reached after 3 minutes. For all subsequent experiments an extraction time of 5 minutes was used. TABLE I EFFECT ON THE EXTRACTION OF PALLADIUM AS THE ACETYLACETONATE FROM SULPHURIC ACID SOLUTION (PH = 0) INTO BENZENE WHEN OTHER SUBSTANCES ARE PRESENT Activity of extract - Counts per Species in 5 ml minute None .. . . . . .. . . . . . . 24,565 0.5 ml of 30 per cent. hydrogen peroxide . . 24,513 1 ml of 30 per cent. hydrogen peroxide . . . . 24,440 0.5 in1 of concentrated nitric acid.. . . . . 24,001 0-5 ml of 70 per cent. perchloric acid . . . . 23,473 0-001 M C1- (sodium chloride) . . . . . . 15,074 0.01 M C1- (sodium chloride) . . . . . . 5,160 0.1 M C1- (sodium chloride) . . . . . . 678 Extraction, per cent. 94.5 94.3 94.0 92.3 90.3 58.0 19.9 2.6December, 19671 SEPARATION TECHNIQUE FOR PALLADIUM 771 The effect of hydrogen peroxide, nitric acid, perchloric acid and chloride ions on the extraction of palladium as acetonylacetonate was investigated, as these substances may be specified in certain analytical procedures.Solutions were prepared containing palladium-103, 0.5 mg of inactive palladium carrier and the substances to be investigated. The solutions were made up to a volume of 5 ml in sulphuric acid so that the final pH was 0. Each solution was then mixed with 5 ml of 0-1 M acetylacetone in benzene for 5 minutes. Table I shows the effect of the various substances added on the percentage extraction of palladium. The extraction of the palladium was accompanied by a colour change of the organic phase to yellow; the rate of this colour change indicated that most of the palladium was extracted in the first few minutes. Chloride ions were found to interfere with the extraction. The yield when chloride ions were absent was 94 f 1 per cent., compared with a yield of only 58 per cent.when the chloride ion concentration was 0.001 M. Higher concentrations of chloride ions reduce the yield of the palladium even further. TABLE I1 CONTAMINATION OF PALLADIUM BY NEIGHBOURING ISOTOPES5 Activity added to aqueous phase, Isotope* Counter counts per minute 11477a1n E ~ , ~ . . . . Well 216,582 109Cd Ec,y . . . . Well 189,528 llomAg /3,y . . . . Well 220,602 9 9 T ~ j3 . . . . . . G.M. 325,181 9 9 ~ 0 p,y . . . . Well 18,680 lo6Ru/Rh p,y . . . . Well 208,922 Activity found in organic phase, counts per minute 125 46 1 61 37 3 281 Contamination, per ccnt. 0.06 0-24 0.03 0.02 0.00 1 1-5 * Symbols used were: Ec electron capture. $ electrons. y gamma radiation. The contamination of the palladium, extracted as the acetylacetonate, by isotopes likely to interfere when palladium is produced by fission or spallation reactions, was examined.The contaminating activity was added to the aqueous phase containing 0.5 mg of palladium carrier. The palladium was extracted with the acetylacetone into the benzene layer, which was then washed with sulphuric acid (pH = 0). The phases were separated, and 2 ml of the organic layer were counted. The extraction of molybdenum can be reduced froin 1.5 to 0-13 per cent. by the addition of hydrogen peroxide to the aqueous phase. The peroxide competes with the acetylacetone for molybdenum ions. The effectivencss of the method for the separation of palladium from a spallation reaction mixture was shown by extracting the palladium from a molybdenum target that had been bombarded with 120-MeV carbon ions in the Manchester University Linac for 30 minutes.The reactions of heavy ions are c ~ r n p l e x , ~ ~ ~ as well as “compound nucleus” formation and its subsequent de-excitation by nucleon and electromagnetic radiation emission, there occur “tunnelling” and “transfer” reactions, so that several different nuclides are formed. The palladium isotopes are formed by the reactions Mo (C,2p,xn) Pd, and by the decay of the silver isotopes produced. The target was dissolved in 8 M nitric acid and left to cool for 2 hours to allow palladium-98 and palladium-99 to decay out. The reaction mixture was evaporated to dryness, the residue dissolved in concentrated sulphuric acid and the pH adjusted to zero (sodium hydroxide - sulphuric acid) ; 0.5 ml of 30 per cent.hydrogen peroxide was added and 5 ml of this solution was treated as previously stated in Procedure. A 4-ml sample of the organic phase was withdrawn for counting and the decay of the palladium fraction followed on an automatic gamma counter. The decay of the component when the longer lived contributions, from palladium-100 and palladium-103, are stripped off is shown The activity of this solution was determined by counting a 2-ml aliquot. The results are summarised in Table TI. The greatest contaminant of palladium is, as shown in Table TI, molybdenum. The yield of palladium was not affected.772 BOSWELL AND MCGEE in Fig. 2. A half-life of 8.4 hours was obtained, which agrees with the published value of the half-life of palladium-101,* thus indicating that the palladium fraction was radio- chemically pure.104 P) C U .- E n L P) v) U s U I 03 Time, hours Fig. 2. The decay of palladium (formed by Mo (C, 2pxn) Pd reactions) extracted as the acetylacetonate into benzene, 2 hours after the end of the irradiation To examine the contamination of a palladium fraction extracted by the above method from a fission product mixture, the active palladium was removed from a 0.25 N nitric acid solution of the fission products by adding 10 mg of inactive palladium carrier and 5 ml of 1 per cent. v/v dimet hylgloxime solutiong and the palladium dimethylgloximate precipitated by centrifugation. This was repeated twice more to ensure the complete removal of the palladium. The solution was evaporated to dryness and heated to destroy any excess of dimethylglyoxime complex.The residue was dissolved in concentrated sulphuric acid, the pH of the solution adjusted to zero, then 0.5 mg of inactive palladium carrier was added and the above extraction procedure carried out. Comparison of the activity of the fission product mixture and the activity of the extracted palladium gave a decontamination factor of lo3 for the separation. This simple, elegant method can be adapted to the many situations when isolation of palladium in a radiochemically pure state is required. We wish to express our appreciation to the staff of the Manchester University Heavy Ton T-inac, and of the Manchester and Liverpool Universities Research Reactor, Risley, for the provision of irradiation facilities. 1. 2 3. 4. 5 . 6. 7 . 8. 9. REFERENCES Ove Hogdahl, T., “The Radiochemistry of Palladium,” Xational Academy of Sciences, Washing- Morrison, G. H., and Freiser, H., “Solvent Extraction in Analytical Chemistry,” John Wiley Starp, J . , and Hladkp, E., Aiaalytaca Cham. Acta, 1963, 28, 227. Perrin, D. D., “Organic Complexing Reagents,” Interscience Publishers, 1964, p. 117. The Radiochemical Manual, Part 1, The Radiochemical Centre, Amersham, Ruckinghamshire. Zucker, A., A . Rev. Nucl. Sci., 1960, 10, 27. Greider, K. R., Ibid., 1966, 15, 291. Xuclear Data Sheets, 1959-65, Academic Press Inc., New York and London, 1966, p. 764. Yogel, A. I., “A Textbook of Quantitative Inorganic Analysis including Elementary Instrumental Received Aprzl 4th, 1967 ton, D.C., NAS NS 3052, 1961. & Sons, Inc., New York; Chapman & Hall Ltd., London, 1957, p. 157. Analysis,” Third Edition, Longmans, Green and Co., London, 1961, p. 512.

ISSN:0003-2654    

DOI:10.1039/AN9679200769

出版商:RSC    

年代:1967

数据来源: RSC

摘要:

A~zalyst, December, 1967, Vol. 92, pp. 773-778 773 Determination of Small Amounts of Formaldehyde in Acetaldehyde BY S. HARRISON (Research Department, Imperial Chemical Industries Limited, Heavy Organic Chemicals Division, Organic House, Billingham, Co. Durham) Two methods are described for the determination of formaldehyde in acetaldehyde based on gas-chromatographic separation of mixtures before, or after, the reduction of formaldehyde to niethanol with borohydride. The latter technique is capable of determining 400 p.p.ni. of formaldehyde in acetaldehyde but the presence of methaiiol and methyl formate will interfere. The former technique, in which a borohydride reactor reduces formaldehyde after separation, will determine down to 10 p.p.m. of formaldcliyde in acetaldehyde in the presence of niethanol and methyl formate.THERE are numerous methods for the determination of formaldehyde involving the use of titrimetry, colorimetry, polarography and gas chromatography. The most sensitive methods are colorimetric, those based on the reactions with chromo- tropic acid and acetylacetone being particularly suitable in the range of 1 to 100 p.p.m. The method, based on the reaction of formaldehyde with chromotropic acid, has been used to determine micro amounts of formaldehyde, e.g., 0-01 to 0.05 mg,l in the presence of large concentrations of various organic compounds, which are removed, in the analytical procedure, by evaporation. In this method formaldehyde can be determined in the presence of a 20,000-fold excess of chloroform, carbon tetrachloride, ethanol, methanol, butyl alcohols, acetone and ethyl methyl ketone, 1000 to 2000-fold excess of acetic acid, propionic acid and benzyl alcohol and 100-fold excess of acetaldehyde and benzaldehyde.Similarly, micro amounts of formaldehyde in gases have been determined2 by the chromotropic acid method, but again acetaldehyde interferes if present in substantial proportion. Attempts have been made in this laboratory to extend the chromotropic acid method to tolerate higher proportions of acetaldehyde, but in spite of testing numerous variations of the analytical procedure it was not found possible to improve the method to tolerate appreciably higher proportions than 100-fold excess of acetaldehyde. An extremely sensitive method developed by Tanenbaum and Bricker3 involved the time-sensitive reaction of formaldehyde with phenylhvdrazine and potassium ferricyanide.This procedure is capable of determining less than 15 rng of formaldehyde in 0.6 ml of sample. However, its application is limited by the fact that methanol, ethanol, butyl alcohols and acetaldehyde interfere. Sawicki4 made a comparative study of colorimetric methods with chromotropic acid, 6-amino-1 -naphthol-3-sulphonic acid (J-acid) and 6-anilino-1 -naphthol-3-sulphonic acid (phenyl-J-acid) for the determination of formaldehyde and formaldehyde-releasing com- pounds. A further sensitive colorimetric method, applicable to less than 10-p.p.m. formaldehyde concentrations, is that based on the reaction of formaldeliyde and acetylacetone in the presence of ammonia to give yellow-coloured diacetyldihydrolutidine.Investigations of the method in this laboratory have shown it to be sensitive down to 1 p.p.m. of formaldehyde, but it will not tolerate more than a 100-fold excess of acetaldehyde. Polarographic methods can be used to determine small amounts of formaldehyde, and have been shown to be sensitive down to about 5 ~ . p . r n . ~ Work carried out by Woodroffe (personal communications), who used a cathode-ray differential polarograph, has enabled formaldehyde down to the 0.4 p.p.m. level to be determined by this technique but, again, will not tolerate more than a 100-fold excess of acetaldehyde.774 HARRISON DETEKMINATION OF SMALL [AnaZyyst, Vol. 92 Methods based on gas chromatography have demonstrated that formaldehyde can be effectively separated from a variety of compounds including a~etaldehyde,~ 9' s8 9 9 ~ 1 0 but, so far, the technique has not been found suitable for determining formaldehyde in the p.p.m.range because of problems in detection at these concentrations. Bambaugh and Bull9 report the gas - liquid chromatographic determination of formaldehyde in water - alcohol mixtures and in high purity (formaldehyde) gas. Kelker also describeslO the separation and quantitative determination of formaldehyde in mixtures containing alcohols (methyl and ethyl), water and ethyl methyl ketone. However, all of the reported separations have been applied to the 1 to 40 per cent. formaldehyde range. The purpose of the present work was to develop methods capable of extending the range of formaldehyde determination down to a few p.p.m.in acetaldehyde, or in the presence of a large excess of acetaldehyde in organic mixtures. At the p.p.m. level there are two main problems, first, that of obtaining a sufficiently good separation system and, secondly, the fact that the detectors normally used in gas chromatography do not have sufficient sensitivity for p.p.m. concentrations of formaldehyde. To overcome the latter problem, methods were considered for converting the formalde- hyde into a more easily determined component. Borohydrides have been used to reduce carbonyl compounds to their alcohols, and this reaction lias been used to remove carbonyl compounds quantitatively from, and to determine total aldehydes and ketones in, alcohols.ll ,12 y 1 3 In the first method developed, the sample is dissolved in water and allowed to react with an aqueous solution of sodium borohydride - sodium hydroxide.The formaldehyde is quantita- tively converted to methanol, which can then be determined by gas - liquid chromatography. In the second method the borohydride (KBH,) is contained in a small reactor tube attached to the end of a gas -liquid chromatographic column and the sample is injected directly on the column. In this case separation of the components takes place before the reduction of the formaldehyde. METHOD I-EXPERIMENTAL REAGENTS- N sodium hydroxide. Sodium borohydride solution-Use a solution of 5 N sodium borohydride (NaBH,) in APPARATUS- A Perkin-Elmer F11 chromatograph was used with the following conditions- CoZzinziz-1O-feet x $-inch i.d.copper tube. Pnckiiig-Ten per cent. polyethylene glycol '' 1500" on Chromosorb W. Detector-Flame-ionisat ion detect or. Pressure-Ten p. s.i.g. Carrier gas-Ni t rog-en. C o I ~ m n temperatitre-60" C. Pre-heater setti+zg--2Q (about 150" C) . 112 jectioiz-One microlitre. PROCEDURE- Weigh accurately about 1 g of sample into 5 ml of ice-cold water. Cool in ice and slowly add 2.5 ml of borohydride solution that has been previously cooled. Mix gently by swirling the solution and then allow it to warm up slowly to room temperature. Finally make up to 10ml with water. Measure the height of the methanol peak, and calculate the formaldehyde content from the calibration graph. CALIBRATION- 400 to 2000 p.p.m. were run as above.and plotted as concentration of formaldehyde against methanol peak heights. Inject 1 pl of this solution on the gas - liquid chromatographic column. Synthetic samples of acetaldehyde containing formaldehyde over the concentration range The heights of the methanol peaks were measuredDecember, 19671 AMOUNTS OF FORMALDEHYDE IN ACETALDEHYDE 775 DISCUSSION By this procedure the formaldehyde is quantitatively converted to methanol. This was shown by running standard solutions of aqueous formaldehyde and standard formaldehyde free methanol solutions and comparing peak heights. I t has been found possible to analyse acetaldehyde - formaldehyde mixtures in ratios as high as 2500 : 1. In 1 p1 of sample, 0.1 to 0.2 pg of methanol can be detected, thus providing a viable method for the determination of formaldehyde at the 400 p.p.m.level, and above. Although this method is an advance on the colorimetric technique, in that it extends the permissible concentration of acetaldehyde and has the advantage of being a simple procedure, it is subject to serious limitations with regard to interfering substances. As the method is based on the reduction of formaldehyde to methanol in aqueous solution, the presence of methanol or any substance, e.g., methyl esters, which will form methanol by hydrolysis or reduction, will interfere. By keeping the reaction solution cool, hydrolysis of methyl acetate and higher esters may be prevented, but it was found that methyl formate hydrolyses under these experimental conditions. METHOD 11-EXPERIMENTAL APPARATUS- under the following conditions was used- For the gas - liquid chromatographic work a Perkin-Elmer F11 Chromatograph operating Colzimn-10-feet x &-inch i.d.Staybrite tubing. Packing-Five per cent. of Citroflex A8 (0-acetyl triethylhexyl citrate), which may be Detector-Flame-ionisation detector. press we-Thirt y p. s. i.g . Linear gas flow-rate--3 cm per second. Carrier gas-Ni trogen. Colztmn temperature-60” C. Pre-heater s e t t i n g 4 (about 200” C). Colzcmn conditioning-The column should be “aged” at 120” C for 12 hours. Injection-One microlit re. Attached to the end of the gas- liquid chromatographic column is a reactor of the following specifications : 3 x $-inch i.d. Staybrite tube packed with evenly ground potassium borohydride. purchased from Pfizer Ltd., and 0.5 per cent.of orthophosphoric acid on Chromosorb G. CALIBRATION- Prepare a 1 per cent. w/w solution of formaldehyde in acetaldehyde. Dilute the solution further with acetaldehyde to give a series of standards containing from 10 to 250 p.p.m. w/w of formaldehyde. Inject 1 . 0 ~ 1 of each standard on the chromatograph and measure the height of peak due to formaldehyde. Plot the peak heights against concentrations. PROCEDURE- Inject 1-0 p1 of sample on the column and measure the height of peak due to formalde- hyde, then calculate the formaldehyde concentration from the calibration graph. If several samples are being analysed it is necessary to allow about 30 minutes between each injection. DISCUSSION Initially, an attempt was made to combine a reactor packed with borohydride and a gas - liquid chromatographic column, with the reactor at the front of the column.In such a system the gas - liquid chromatographic column would be required to separate methanol from ethanol, residual acetaldehyde and other components that might be present. Satis- factory separations were obtained, but it was difficult to obtain reproducible quantitative results at the 50 to 200 p.p.m. of formaldehyde level, and the life of the reactor was short.776 HARRISON DETERMINATION OF SMALL [,4naZyst, Vol. 92 However, these preliminary experiments did indicate that such a technique could form the basis of a viable analytical method. The alternative arrangement was to have the reactor after the column, but this would require a separation system that would separate formaldehyde from other components, particularly acetaldehyde, and preferably one in which formaldehyde would have a shorter retention time than acetaldehyde.The latter condition is not obtained in most of the gas - liquid chromatographic separations reported in the literature, but KelkerlO describes a gas - liquid chromatographic system, with Citroflex AS as a stationary phase, which achieved this type of separation with formaldehyde in the several per cent. range. A column was therefore prepared as follows: 10-feet x &inch i.d. stainless-steel tubing, packed with 5 per cent. Citroflex AS on Chromosorb G, and incorporated in a Perkin-Elmer F11 chromatograph. Various mixtures of formaldehyde and acetaldehyde were examined and it was shown that separations were taking place at relatively high concentrations of formaldehyde.However, at the levels required, i.e., 50 to 1000 p.p.m. of formaldehyde, there were no detectable peaks for formaldehyde, as can be seen in the gas - liquid chromato- graphic traces in Fig. 1 with reactor, and Fig. 2 without reactor. I" u, W 0 I U + I" 0 I. f ' U 0 I h b 2. Fi.g. 1. Fig. 2. Chromatogram for the determination of formaldehyde with Chromatogram with mixture as for Fig. 1 without potassium potassium borohydride reactor borohydride reactor At this stage a borohydride reactor (3-inches x $-inch i.d. tube, packed with potassium borohydride) was attached to the end of the gas - liquid Chromatographic column and a further series of formaldehyde - acetaldehyde mixtures was examined.The formaldehyde was con- verted to methanol in the reactor, and thus made it possible to detect the equivalent of 50 p.p.m. of formaldehyde. At this level considerable tailing of peaks was experienced, but this was substantially reduced by incorporating 0.5 per cent. of orthophosphoric acid in the column packing. I t then became possible to detect down to 5 p.p.m. of formaldehyde in acetaldehyde (see Fig. 3).December, 19671 AMOUNTS OF FORMALDEHYDE IN ACETALDEHYDE 777 A series of formaldehyde standard solutions in acetaldehyde covering the range 10 to 200 p.p.m. was examined, and a linear peak height against concentration of formaldehyde relationship was obtained (see Figs. 3, 4 and 5). 3. J - 4. +-- 5. Fig. 3.Fig. 4. Chromatogram of 14 p.p.m. of formaldehyde in acetaldehyde Chromatogram of 204 p.p.m. of formaldehyde in acetaldehyde Chromatogram of 6 1 p.p.m. of formaldehyde in acetaldehyde containing propylene Fig. 5. As a check on possible interfering substances, a random mixture was prepared containing formaldehyde, acetaldehyde, methyl format e , ethyl acetate , me thy1 acetate , vinyl acetate , methanol, ethanol, acetone, propylene oxide and propylene. With adjustment of tempera- ture and pressure conditions good separations were obtained (as can be seen in Fig. 1). CONCLUSIONS Colorimetry and polarography both provide techniques for determining sinall amounts of formaldehyde but are limited by interference from the presence of acetaldehyde. More versatile in application are the two methods described, which are based on gas- chromatographic separations and reduction of formaldehyde with borohydride.In method 11, this versatility is combined with a sensitivity that enables 10 p.p.m. of formaldehyde in acetaldehyde to be determined easily (see Table I). TABLE I DETERMINATIOX OF FORMALDEHYDE IN ACETALDEHYDE (METHOD 11) Added, p.p.m. Found, p.p.m. 14 16 13 33 32 34 61 58 68 109 109 107 156 152 - 204 205 204778 HARRISON The separation of a random mixture of liquid organic components indicates the general usefulness of the method, thus considerably extending the field of application for the deter- mination of small amounts of formaldehyde in the industrial field. The author thanks Mr. D. L. Stanton for his assistance in this work. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. REFERENCES Bricker, C. E., and Vail, W. A., Analyt. Chem., 1950, 22, 720. Altshuller, A. P., Miller, D. L., and Sleva, S. F., Ibid., 1961, 33, 621. Tanenbaum, M., and Bricker, C. E., Ibid., 1951, 23, 354. Sawicki, E., Hauser, T. R. and McPherson, S., Ibid., 1962, 34, 1460. Sandler, S., and Chung, Y-H., lbid., 1958, 30, 1252. Schepartz, A. I., and McDowell, P. E., l b i d . , 1960, 32, 723. Sandler, S., and Strom, R., Ibid., 1960, 32, 1890. Stevens, R., Ibid., 1961, 33, 1126. Bombaugh, I<. J . , and Bull, W. C., lbid., 1962, 34, 1237. Kelker, H., Z. analyt. Chem., 1960, 176, 3. Lyttle, D. A., Jensen, E. H., and Struck, W. A., Analyt. Chem., 1952, 24, 1843. Cochran, E., and Reynolds, C. iz., Ibid., 1961, 33, 1893. Sobotka, M. and Trutnovsky, H., Microchew. J . , 1959, 3, 211. Brown, 13. C., and Ichikawa, I<., J . Amev. Chew. Soc., 1962, 84, 373. Received September 13th, 196G

ISSN:0003-2654    

DOI:10.1039/AN9679200773

出版商:RSC    

年代:1967

数据来源: RSC

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Analyst, December, 1967, Vol. 92, p p . 779-781 779 A Modification of Miles’ Method for Determining Azinphos-methyl Residues in Crops BY N. A. SMART (Plant Pathology Laboratory, Ministry of Agriculture, Fisheries and Food, Harpenden, Hertfordshire) Meagher’s, Bluman’s and Miles’ methods for determining azinphos- methyl residues were assessed on a range of crops. Some shortcomings were encountered with the three methods and, to overcome them, a modi- fication of Miles’ method, involving the use of acetone extraction, is proposed and evaluated. The cleaned-up extract can also be used in an established chromatographic identification procedure. GIAKG and Scliechter,l Kawashiro and Takeuchi,2 Meagher, Adams, Anderson and MacDougall,3 Bates,* Miles5 and Adams and Anderson6 have published specific methods for the quantitative determination of residues of azinphos-methyl, S-(3,4-dihydro-4-oxobenzo- [ d ] - ( 1,2,3)-triazin- 3-ylmethyl) dimethyl phosphorothiolothionate, in crops.Meagher’s method has been adopted as A.O.A.C. first action,’ following collaborative s t ~ d y . ~ ? ~ ? ~ An unpublished method of Bluman has also been investigated collaboratively by A.O.A.C.1° Several general screening techniques for organophosphorus pesticide residues, such as those of Batesll and Kovacs,12 may also be used to determine azinphos-methyl residues. We required a method for determining azinphos-methyl residues in a range of fruits and vegetables to serve as a basis for collaborative work with other laboratories in the United Kingdom and Europe.The method should attain, in the hands of reasonably experienced workers, an accuracy of within a few tenths of a part per million of insecticide, and should preferably be suitable for use in an analytical laboratory that is not equipped with highly specialised apparatus. The methods of Meagher, Bluman and Miles were studied on six crops by one worker, so that the relative merits and defects of the methods could be assessed without variation caused by the different techniques of workers making comparison difficult or invalid. The crops chosen for investigation were apples, pears, cucumbers, tomatoes, Brussels sprouts and peas. Meagher’s method gave a mean recovery over all determinations of 79 per cent., with a standard deviation of k0-03 p.p.m. at 1 p.p.m. level over 21 determinations. The recoveries with peas were only 63 per cent.The method was lengthy because of emulsion difficulties. Bluman’s method gave a mean recovery over all determinations of 78 per cent., with a standard deviation of k0.07 p.p.ni. at 1 p.p.m. level over 21 determinations. Recoveries with cucumbers were only 55 per cent. The method is rapid: two determinations can easily be made in 1 day and six in 2 days. Miles’ method gave a mean recovery over all determina- tions o€ 78 per cent., with a standard deviation of 1044 p.p.m. at 1 p.p.m. level over 21 deter- minations. The original method described the maceration of the crop sample with chloroform but, in this laboratory, it led to a variable recovery of about 50 per cent. from apples because of the difficulty in separating the chloroform phase.Shaking the diced fruit with chloroform was used to obtain the above results. As Meagher’s method was time consuming, Human’s method involved the extensive use of toxic benzene and gave low recoveries with cucumber and Miles’ method gave in- complete extraction, a modification of Miles’ method, involving an efficient acetone extraction, was developed. A further advantage gained by using acetone extraction was that the initial extract could be used for other established residue analysis procedures (e.g., that of Rates), which might not work following a straightforward chloroform extraction. The chromato- graphic systems of Bates were used to identify the insecticide.780 SMART: A MODIFICATION OF MILES’ METHOD FOR [Analyst, Vol.92 EXPERIMENTAL A 200-g sample of fruit or vegetable was macerated with 200 ml of acetone for 5 minutes in a Waring blender and filtered on a Whatman No. 541 filter-paper on a slit-sieve Buchner funnel. The solid on the filter-paper was again macerated with 200 ml of acetone for 5 minutes and filtered. The combined filtrates were filtered again through two thicknesses of Whatman No. 541 filter-paper. The clear filtrate was diluted with 300 ml of water and one quarter taken for analysis. The aliquot of the aqueous acetone extract was shaken with successive 50,25, 25 and 25-ml portions of chloroform in a 500-ml separating funnel, shaking it only gently for the first two extractions. Any emulsions were readily broken by warming the funnel and its contents under the hot water tap, swirling, and adding a few milligrams of sodium chloride.The combined chloroform extracts were washed with 50 ml of water, and the washing back-extracted with 25-ml of chloroform. The combined chloroform extracts were evaporated just to dryness in a 250-ml flask on a steam-bath in a current of air. The residue was then taken up in 10 ml of acetone, cleaned up, and determined by Miles’ procedure. CHROMATOGRAPHIC IDENTIFICATION A volume of the cleaned-up extract from the method, corresponding to a 25-8 sample, was evaporated to small volume in a flask on the water-bath and then just to dryness in a tapered test-tube. The residue was taken up in about 20 to 25 p1 of chloroform and spotted 1 inch from the corner of a 10 x 10-inch Whatman No.20 chromatographic paper. Marker azinphos-methyl spots were applied in two adjacent corners. The paper was then dipped in 30 per cent. v/v dimethylformamide in acetone and, after drying, it was run in hexane. After drying, the paper was dipped in 5 per cent. v/v liquid paraffin in diethyl ether, dried, and run at right angles in diethylformamide - water (1 + 1). The position of insecticide on the chromatogram was detected with 2,6-dibromo- ~-benzoquinone-4-chloroimine. RE s u LTS Reagent blanks were 042 and 0-06 p.p.m. of apparent azinphos-methyl. Table I gives the blank values and recovery results obtained by using the modified Miles’ method on locally purchased crops. TABLE I MODIFIED MILES’ METHOD FOR ANALYSIS OF AZIKPHOS-METHYL I S FRUITS *%XD VEGETABLES Kccovcry of 1 p.p.m.of insecticides* Crop blank,? Crop p.p.m. Applcs . . . . . . 0.04 Pears . . . . . . 0.13 Cucu tnbers . . . . 0.09 Tornatocs . . . . . . 0-08 Brussels sprouts . . . . 0.14 Peas . . . . . . 0.06 -- Mean, p.p.m. 0- 80 0.79 0.73 0.80 0.70 0.65 1 Standard deviation Number of p.p.m. determinations 0-04 6 2 2 - - 0.03 5 * 0.03 > - - - 3 I * Corrected for crop blank and reagent blank. j- Mean of two determinations and corrected for rcagcnt blank. A 25-pg extract of insecticide from 25 g of apples, pears, cucumbers, tomatoes, Brussels sprouts or peas was clearly visible as a red - brown compact spot having K, 0.06 to 0.15 in hexane and R, 0.80 to 0.85 in 1 + 1 dimethylformamide - water. No other spots developed, except with Brussels sprouts when a yellow - brown spot also appeared, R, nil in hexane, K , 0.8 in 1 + 1 dimethylformamide - water.This spot, although near the azinphos-methyl, was quite distinct from the insecticide. The RF values of other organophospliorus insecticides that might be present in practice are given in Bates’ paper. This modification of Miles’ method overcomes the difficulties of Meagher’s method, Bluman’s method and Miles’ original method, and merits collaborative study. The method is as accurate and sensitive as Meagher’s method. One quantitative determination takes 3 hours and four may be made in 1 day.December, 19671 DETERMINING AZINPHOS-METHYL RESIDUES IN CROPS 781 1 . 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. REFERENCES Giang, P. A., and Schechter, M. S., .J. Agric. Fd Chem., 1958, 6, 845. Kawashiro, I . , and Takeuchi, H., Bull. Natn., Hyg. Lab., Tokyo, 1958, 76, 59. Meagher, TV. R., Adams, J. M., Anderson, C. A., and MacDougall, D., J . Agric. Fd Chem., 1960, Bates, J. A. R., Analyst, 1962, 87, 786. Miles, J. R. W., J . Ass. OH. Agric. Chem., 1964, 47, 882. Xdams, J. M., and Anderson, C. A., J . Agric. Fd Chem., 1966, 14, 53. Cox, W. S., .J. A s s . 08. Agric. Chem., 1961, 44, 188. -__ , Ibid., 1962, 45, 406. -, Ihid., 1963, 46, 229. ---, I b i d . , 1964, 47, 280. Bates, J . -4. R., Analjist, 1965, 90, 453. l i o ~ a c s , 31. F., J . Ass. Off. Agric. Chem., 1964, 47, 1097. 8, 282. Received January 27th, 1967

ISSN:0003-2654    

DOI:10.1039/AN9679200779

出版商:RSC    

年代:1967

数据来源: RSC

摘要:

782 Analyst, December, 1967, Vol. 92, p . 782 The Separation of Dieldrin from Pentachlorophenol BY J. N. WILSON, M. C. FRANKS AND D. R. SHERLOCK (The British Petroleum Company Limited, B.P. Research Centre, Chertsey Road, Sunbury-on-Thames, Middlesex) BEFORE a pesticide can be marketed, the governments of many countries require that the speci- fications available include acceptable methods of analysis for the active constituents. Recently such a specification, for a wood preservative, was required to include a method for the deter- mination of 0.5 per cent. of dieldrin in the presence of 5 per cent. of pentachlorophenol. The base solvent was an aromatic petroleum fraction. The active principal of dieldrin is HEOD, I. c1 I Being heavily chlorinated it may readily be determined by chlorine assay, for example, by the oxygen-flask technique,l but as this determination is not possible in the presence of a second chloro-compound, a preliminary separation must be made.Removal of the pentachlorophenol by extraction with aqueous alkali is difficult to achieve and leads to inaccurate results because of the ~ccurrence of entrainment and sometimes emulsion formation. These difficulties have been overcome by the use, under non-aqucous conditions, of a macro-reticular strong anion-exchange resin, such as De-Acidite K (Permutit Company Limited) or Amberlyst 29 (Rohm and Haas). A column of the resin is first generated in the hydroxide form by passing four bed volumes of 2 N aqueous sodium hydroxide. After copious washing with de-ionised water to remove excess of alkali and all traces of chloride (the resins are supplied in the stable chloride form), water is removed by passing dry methanol.The sample is diluted with dry methanol and percolated through the resin column. The pentachlorophenol is retained on the resin, while the dieldrin is found in the effluent. The column is washed with four bed volumes of methanol, the washings being added to the effluent. After removal of methanol on a water-bath, the residue is assayed for chlorine by the oxygen-flask technique.l Hydrochloric acid is determined by the method proposed by which involves titration with a solution of mercury( ii) nitrate in aqueous ethanol, and the percentage of dieldrin calculated. Somc typical results are given in Table I. TABLE I DETERMINATION OF l>IISLI)IZIN 1<Y THE OXYGEN-FLASK TECHNIQUE Solution in aromatic solvent Dieldrin, per cent., calculated from chlorine in effluent Pentachlorophenol, 5 per cent.. . . . . . . . . . 0.03 Dicldrin, 0-9 pcr cent. . . . . . . . . . . . . 0.9 1 Pentachlorophenol, 5 per cent., with dieldrin, 0.5 per cent. . . (i) 0.50; 0.49; 0.51 (ii) 0.51; 0-51 The separation procedure may readily be adapted to acconimodate samples varying widely in size and concentration of chlorinated compounds. In the present experiments, 1 g of resin, as supplied, per g of sample ( 5 per cent. pentachlorophenol) was used. Fifty-milligram samples of the residue were adequate for the oxygen-flask combustion. Although the method has been used only for this specific separation, it would, with minor modifications, serve equally well to separate other chlorinated pesticides commonly used in combination with pentachlorophenol, for example, BHC and DDT. REFERENCES 1. 2. TVhite, D. C., Mikrochiin. Arla, 1961, 449. Analytical Methods Committee, Analyst, 1963, 88, 416. Received June Gth, 1967

ISSN:0003-2654    

DOI:10.1039/AN9679200782

出版商:RSC    

年代:1967

数据来源: RSC

摘要:

Analyst, December, 1967, Vol. 92, p p . 783-788 7 83 Book Reviews CHROMATOGRAPHIC REVIEWS, PROGRESS IN CHROMATOGRAPHY, ELECTKOPHOKESIS AN11 RELATED METHODS. VOLUME 8. Edited by MICHAEL LEDEREK. Pp. viii + 298. Amsterdam, London and New Yorli: Elsevier Publishing Company. 1966. Price 110s. This series of annual volumes, most ably edited by 32. Lederer, has, since its inception in 1959, undergone several changes in the choice and presentation of the subject matter. N-hat started as a vehicle for review articles worth reprinting has gradually developed into a collection of original contributions by specialists chosen from fields of particular interest. As such, each volume performs a valuable function in providing information in a co-ordinated, comprehensive and time-saving form.The appearance quite recently of a similar American series does by no means make the publication of Chroniatographic Reviews redundant. The present volume opens with a most interesting chapter by G. Guiochon, on the flow of gases in porous media, raising fundamental issues connected with the successful operation of gas- chromatographic columns. The review may, in parts, be too mathematical for the average chemist, but it also contains a great deal of practical advice for the correct measurement of flow- rate, gas volume and porosity of column, including descriptions of flow-rate regulating and pro- gramming systems. Of equal interest is the chapter, by K. L. Levy, on the rapidly expanding technique of pyrolysis gas chromatography. The analysis of products of pyrolysis, or thermal breakdown, by gas chromatography for identification and characterisation purposes is akin, in principle, to several other techniques in use, i.e., those based on a combination o f pyrolysis with mass spectrometry, infrared or ultraviolet spectrophotometry.Pyrolysis gas chromatography is particularly useful in the analysis of complex non-volatile, insoluble organic materials, e.g., some synthetic or natural polymers. The use of gas chromatography for trace analysis is authoritatively surveyed by J . JanAli and collaborators. Methods may depend on the sensitivity of detectors, on preliminary concen- tration of the trace component, or both. Consequently, the authors describe, extensively, the design and physical principles of various highly sensitive detectors, and advise on their characteristics and suitability.The importance of trace analysis a t concentration levels of p.p.b., in problems of air pollution, industrial hygiene, pesticides and herbicides in agriculture, and additives in the food industry, is well known. The chapter by A. Kuksis on quantitative lipid analysis by combined thin-layer and gas - liquid chromatographic methods should be of great use to clinical and physiological chemists concerned with the preparation and analysis of lipoproteins, phospholipids and lipid patterns in human and animal tissues. X closely related subject, the chromatography of triglycerides, is reviewed by F. R. Padley. The difficulty of analysis of a large number of similar triglycerides occurring in natural fats has been reflected in the great variety of techniques developed for the purpose of producing reliable results.Surveying the various techniques of column, paper, thin-layer and gas - liquid chromato- graphy, the author concludes that, although there is still no single tcchnique for the analysis of natural fats, the applicatioii of a combination of several techniques, including thin-layer and gas - liquid chromatography, appears to be yielding the most satisfactory answer to the problem. In a brief chapter on fibrous proteins, 2. Deyl and J . Rosmus deal with separation techniques for collagen, myosin, keratin and their degradation products. The information includes separation by gel filtration, electrophoresis and carboxymethylcellulosc columns. Interesting applications of techniques, based on various types of ion-exchange papers, to the resolution of complex mixtures of inorganic ions, e.g., radionuclides and lanthanide elements, are described by G.Alberti, an active worker in this field. Although work utilising paper impregnated with organic ion-exchange resins is mentioned, the review deals predominantly with results obtained by use of paper impregnated with inorganic ion exchangers, such a s zirconium phosphate and ammonium molybdophosphate. From the same laboratory, a review by V. Carunchio and G. Grassini Strazza makes up the volume by reporting on the use of chromatography in the study of structure, reactivity and synthesis of inorganic co-ordination compounds. Separations are A technique that promises higher sensitivity and selectivity can only be welcome.784 BOOK REVIEWS [Analyst, Vol.92 effected either on the basis of charge differences or configurational differences. This lucidly xvritten chapter should prove particularly helpful to research workers in the more theoretical fields of inorganic cliemistry. The Tvlunie can be unhesitatingly recommended to anyone interested in chromatographic methods. The only feature open to criticism is the several pages of commercial advertisements carried a t the back of the book. I t is iieatly produced, well illustrated and reasonably priced. n. GROSS TRACE CHARACTERILATIOS-~H~~~~IC~ZL ASU ~’HYSICAL. By W. i i a u r j ~ Jl;:Isr;e and BOURDON F. SCRIUNER. Pp. xviji + 580. Ifashington, D.C. : National Bureau of Standards Mono- graph 100.1967. Price $4.50. I t is obvious that our knowledge of the significaiice of trace constituents is increasing daily, with studies in this direction stimulated by the ltnown or suspected rale of trace elements in a11 phases of our everyday life. From the smallest individual organism to man himself, their presence in prescribed amounts is essential for a healthy existence, while their absence may have the opposite effect. In this modern age, E . R . , in engincering, especially nuclear engineering, limitations are imposed on the presence of some elements for entirely new reasons, and the analyst is faced with additional problems involving determinations a t the parts, or even fractions of a part, per million level. In October 1966, the U.S. National Bureau oi Standards held its first Materials Research Symposium, in Gxithersburg:, Maryland, and this publication contains the invited papers and summaries o f other papers presented a t that Symposium, together with subsequent Symposium discussions.This occasion must have been unique in bringing together so many internationally recognised experts from a wide field of scientific interests. Symposia so often tend to provide a common plat- form for exhaustive discussion within narrow areas of competence, but the title of this Symposium was ideally suited to remove the demarcations that still exist, for example, between the physicist, on the one hand, and the chemist on the other. The main chapter headings are Trace Characterization and the Properties of Materials; Electrical Measurements for Trace Characterization ; Trace Characterization by Electrochemical Methods; Optical and X-ray Spectroscopy; Effects of Trace Impurities on X-ray Diffraction; Physica 1 Optical Methods ; Chemical Spectrophotometry in Trace Characterization ; Radioactivity Techiiiqucs in Trace Characterization ; Nuclear Methods ; Spark Source Mass Spectrometric i4na.lysis of Solids ; Preconcentration in Trace Analysis ; and The Study of Crystal Imperfections by Rleans of Optical Methods and by AIeans of Electron Microscopy and Electron Diffraction.The bus!- analyst, who tends to work within the narrow confines dictated by his particular circunistances, sl~ould benefit from this authoritative appraisal of how the same problems are approached elsewhere, and a publication such as this (the reviewer has queried its low price) that gives a clear, concise and up-to-date account of the statc of the art, should have a strong appeal to anyone involved in “Trace Characterization. ” M‘.’r. ELWELL CONTA~~IKATIOI~ .ANAL\-SIS AKD CONTIWL. By JAMES UWYER. Pp. vi 1 343. New York: \I‘ith the advancement of technology, there has been an increasingly important need to control particulate contaminants and to apply stringcnt requirements to them. For those intercsted in particulate contamination, this book provides a comprehensive review of the practical aspects of the subject. The titles of the 11 chapters give a general indication of the scope of the book as the following show : Particles and droplets in gases-sources : Properties of aerosols : Aerosol samp- ling : Sample analysis : Contaminants on surfaces-sampling and analysis : Contamination control of airborne particulates : Control of contaminants in liquids : Cleaning o f surfaces.Contamination of plant and components by dirt is a common but serious problem today, and those working in a wide variety of industries will find this book useful, in fields as diverse as elec- tronic devices, aerospace or the chemical, photographic and food industries. Dust or other airborne particles need to be excludcd from industrial processes, and the author describes the methods for controlling this contamination and its analysis, including sampling for particles of micron size, although specific details of analytical procedure are omitted. However, the biblio- graphy gives copious references to the literature on thc subject.lieinhold Publishing Corporation. 1966. Price 120s.December, 19671 BOOK REVIEWS 785 The chapters on control of contaminants in liquids and the cleaning of surfaces succeed in condensing considerable information on two vast subjects into a small space. The various methods of filtration of liquids are referred to, as also are the use of coagulants and coagulants aids in settling particles in suspension in water. Similarly, the chapter on cleaning surfaces briefly refers to acid, alkali, emulsion and vapour-phase cleaners, and the methods used for their application. It would have been helpful, however, if the bibliography had contained more references to the literature on these subjects to supplement the understandably brief descriptive material.E. L. STREATFIELD PROGRESS IN NUCLEAR MAGXETIC RESONANCE SPECTROSCOPY. Volume 2. Edited by J . IV. Oxford, London, Edinburgh, 1967. Price 90s. This series is of considerable importance in the rapidly expanding ficld of high resolution nuclear mag- netic resonance spectroscopy. The object of this series is to make available a continuous supply of up-to-date authoritative reviews dealing with topics of current interest ; the second volume certainly satisfies this condition. The contents of volume 2 include work on high resolution nuclear magnetic resonance, and also on magnetic resonance of paramagnetic systems. I congratulate the editors of this series for continuing to make the series readable to both nuclear magnetic resonance spectroscopists, and electron spin resonance spectroscopists. The book continues with the high standard set by the first volume of the series and will be extremely useful, particularly to nuclear magnetic resonance specialists.The chemical shift of nuclei in molecules and solids is determined by the interaction of the nuclear niagnetic moment with orbital currents of electrons induced by the applied magnetic field. In these determinations perturbational methods are employed, which yield results that are examined in detail, and justifi- cation for its use is given. Calculations are made for atoms, molecules and solids. 2\11 results are summarised. The next section by Buckingharn and McLaughlin deals with high resolution nuclear magnetic resonance in partially oriented molecules.Both molecules and liquids are discussed in some detail, and all results on anisotropies in the shielding constants, molecular structural parameters, the absolute signs of isotropic spin-coupling constants, anisotropies in spin-coupling constants, nuclear quadrupole coupling constants and the mean orientation of the molecule in an isotropic environ- ment are discussed and tabulated. De Boer and van Willigen then discuss nuclear magnetic resonance of paramagnetic systenis and survey the theoretical background of the direct and indirect methods of studying paramagnetic systems by using nuclear magnetic resonance techniques. The fourth chapter, on the calculations of line shapes by density matrix methods, by Lyndcn- Bell contains description of the density matrix and those of its properties which are used in nuclear magnetic resonance problems, descriptions of the nuclear magnetic resonancc spectrum of a single spin nucleus by means of the density matrix and discussion of thc line shapes in systems with chemi- cal exchange.The concluding chapter by Zurcher, on the cause and calculation of proton chemical shiits in non-conj ugated organic compounds, discusses general theory as applicd to methyl groups and rigid systems. The binding, the typography and the index are good, and the price is reasonablc a t 90s. EMSLEY, J. FEENEY and L. H. SUTCLIFFE. New York, Toronto, Sydney, Paris and Braunschweig : Perganion Press. Pp. viii + 271. This book is the second volume in ;t series edited by Emsley, Feeney and Sutclifie.Chapter 1 by O’Reilly is concerned with chemical shift calculations. Relaxation effects and double resonance are also discussed in some detail. H. RI. XSSENHEIM A SYSTEMATIC APPROACH TO T H E INTERPRETATION OF INFRARED SPECTRA. By HERMAN -4. SZYMANSKI. Pp. vi + 154. New York: Hertillon Press. 1967. Price $2.00. Any publisher who is sufficiently enterprising to issue a well printed and lavishly illustrated advanced text for thc price of two dollars deserves to succced, and i t is therefore all the more disappointing to have t o say that this text cannot be unreservedly recommended. In this field, perhaps more than any other, it is vital that the student should grasp the limitations of the tech- nique as clearly as he understands its potential, and this is not brought out as clearly as i t should be.Indeed, the foreword contains the statement “If the spectrum is a complete unknown he (the student) should be able to make fairly reasonable assignnients of all bands.” I do not believe the786 BOOK REVIEWS [Analyst, Vol. 92 author intended this to be taken literally, but it illustrates the loose wording that could well generate a dangerous degree of over-confidence. There are other deficiencies also ; the illustrations, for example, are not always well chosen for teaching purposes. The student will be confused by a spectrum illustrating a primary amide in which the separate Amide I and I1 bands cannot be distinguished (p. 119), and probably also by the inclusion of the spectra of gases in which rotational structure is present. The formulae on p.104 include three identical structures that are assigned different carbonyl frequencies, and the interpretation of the doubling of the CO band of benzoyl chloride (p. 107) is not that which is generally accepted. I t is, of course, always easy for a reviewer to pick on defects of this kind and to ignore the fact that the main bulk of the text is factually sound and informative. For the man with some know- ledge and experience this is a useful text that is good value for money, but for the reasons given I would be rather more hesitant in putting i t in the hands of a complete beginner in this field. L. J . BELLAMY SIMPLIFIED ANALYSIS OF HYUROPONIC SOLUTIONS. By M. SCHWARZ and E. SZEKELY. Pp. The National Council for Research and Development, The Negeve Institute for This booklet, in typescript form, is intended for use by farmers and scientifically unskilled persons concerned with growing vegetables, flowers and fruits under conditions calculated to give optimum growth by using the techniques of soilless culture, where accurate control of nutrient concentration and pH is essential and the accumulation of undesired elements must be prevented.The use of sophisticated equipment and lengthy processes is avoided. Relatively straightforward tests for the estimation or determination of nitrate, ammonium, phosphate, iron, boron, chloride, zinc and copper, and manganese, often involving comparison with standard nutrient solutions for which the preparations are given, are clearly described.Minor printing errors not indicated by the errata slip are unimportant. The booklet is well worth looking a t for the new methods and modifications of accepted methods developed a t the Negeve Institute. Of general interest are tables of optimum concen- trations of nutrients and the pH recommended in each case for growing various plants in gravel culture. iv + 34. Arid Zone Research, Hydroponic Department. Beer-Sheba, Israel. 1967. The bibliography lists eleven books published from 1944 onwards. B. J . MOODY AKALITICHESKAYA KEAKTSIONNAYA GAZOVAYA KHROMATOGRAFIYA (ANALYTICAL REACTION GAS CHROMATOGRAPHY). By V. G. BEREZKIN. Pp. 184. Moscow: Iz. Nauka. 1966. Price 56 Kop. The term “reaction gas chromatography” was used by F. Drawert in 1962 at the Fourth Symposium on Gas Chromatography at Hamburg to describe the miscellany of procedures in which chemical reactions are used in gas-chromatographic schemes.The present monograph is devoted to analytical uses of reaction gas chromatography ( c j . V. G. Berezkin and 0. L. Gorshunov, Usp. Khinz., 1965, 34, 1108) as distinct from kinetic and catalytic studies. The reactions take place in reactors, which can be situated either before or after the column, but analytical methods in which chemical conversions of a sample are carried out as separate operations in vessels not linked with the gas-chromatographic column are excluded from “analytical reaction gas chroniato- graph y . ’ ’ Among the reasons lor combining chemical transformations with gas chromatography arc the possibility of the formation of new compounds that are more easily separated on the usual columns or more easily detected, or both, the possibility of determining unstable and highly reactive com- pounds, and the possibility of extending the range of the flame-ionisation detector to the deter- mination of nitrogen, oxides of carbon, water, etc.The first methods published in the de-limited field were those of N. H. Ray (Analyst, 1955, 80, 853), who used a column of bromine-impregnated charcoal to absorb ethylene before determining the impurities originally present in the ethylene on a column of activated charcoal, and A. E. Martin and J. Smart (Nature, 1955, 175, 422), who oxidised organic vapours eluted from a column to carbon dioxide (and water), and then used an infrared analyser.In this book the author summarises the work already published in the field, both in theory and practice, giving short accounts of methods and details of ranges of application. He attempts some systematisation of results and makes suggestions on the possible directions of future development. References are given a t the end of each of the 8 chapters and the total number, without allowing for some repetitions, is over 350, some of which are as recent as 1966,December, 19671 BOOK REVIEWS 787 In Chapter I, the main paths of development of analytical-reaction gas chromatography are outlined, further details being given in subsequent chapters. Chapter I1 is mainly theoretical, and Chapter I11 describes possible types of apparatus trains. Chapter IV is concerned with the analysis of complex mixtures by the use of hydrogenation, dehydrogenation, esterification, hydrolysis, pyrolysis (of volatile compounds), dehydration, decarboxylation and oxidation.Chapter V deals with the determination of impurities by reactions leading to the absorption of the main component before the column separation (e,g., N. H. Ray, Analyst, 1955,80, 853), processes that are effective only for impurities of a different type; the formation of more volatile compounds from the impurities, e.g., in the determination of sulphur in organic compounds by hydrogenation, followed by condensation of hydrogen sulphide and methane and their gas-chromatographic separation (I. Okuno, J . C. Morris, and W. E. Haines, Analyt. Chem., 1962,34, 1427) ; the formation of compounds of low volatility from the impurities, e.g., in the determination of carbon dioxide and hydrogen sulphide as impurities by absorbing them in ethanolamine a t room temperature, followed by their release at a higher temperature for separation on a column of hexadecane; the conversion of gases that are not registered by a flame-ionisation detector to others that can be detected, e.g., in the determination of oxygen in a two-stage operation by converting it to carbon monoxide, followed by the reduction of the latter to methane (V.G. Berezkin, A. E. Mqsak and L. S. Polali, Izv. Akad. Nauk SSSR, Ser. Khim., 1964, 1871) ; and by many reactions of other types. Analytical-reaction gas chromatography is of great value in the analysis of polymers and other non-volatile compounds (Chapter VI) , as decomposition into simpler and more volatile compounds by pyrolysis, or sometimes by oxidation processes and radiolysis, is essential for the application of the usual methods of gas chromatography, although the author refers to a non- destructive method for detecting functional groups, determining molecular weights and studying phase transitions. In this method the stationary liquid phase (the polymer) is the unknown factor and the mixture of gases for chromatographic separation is the known factor.From the gas- chromatographic spectra of the standard mixtures much information on the composition of the polymer can be obtained. In Chapter VII, various methods of elemental organic analysis and the determination of carbon-to-hydrogen ratios are described, and the author draws the conclusion that reaction gas- chromatographic methods are generally simpler than those normally used in elemental analysis, although the results are comparable in accuracy, those for nitrogen showing smaller errors.Chapter VIII deals with reactions that can be used to change the sensitivity and selectivity of detectors, and to provide information on functional groups. This comparatively short volume is likely to be valuable for reference as it is the first to appear in this heterogeneous field. At present the subject is not categorised in the Index to “Analytical Abstracts.” The book can be recommended to those in search of fresh ideas for the solution of a variety of analytical problems.G, S. SMITH CHEMISTRY. A CONCEPTUAL APPROACH. By CHARLES E. MORTIMER. Pp. xii + 692. New 1967. Price 71s. 6d. The acquisition of a good appreciation of the fundamentals of chemistry is achieved in niany ways, and no two students are likely to have had precisely the same basic training. We live in an age when scientific innovations rapidly become part of our everyday life, when new approachcs are made to elucidate, or extend, the theories of yesterday, and modern scientific tools are available for solving current problems. Whilst the basis of our modern scientific thinking remains largely unchanged, those responsible for teaching advanced chemistry and its inseparable associations with other branches of related sciences, have an increasingly difficult task to perform.Professor Mortimer has a reputation for presenting general chemistry in such a way as to make the subject interesting and understandable, and the impression gained from reading this publication is that the claim is justified. The author displays a commendably clear style of presentation, and the reader is helped, not only by the clarity and relative simplicity of the reading matter, b u t by the typography of the book, and the excellent diagrams and tables that are attractively presented in a blue colour scheme. Throughout the book, problems are posed, and solved with stepwise explanations, and answers to selected numerical questions are given in the final pages. Each chapter concludes with a list of selected references, under the heading, Some Suggested Readings.York, Amsterdam and London: Keinhold Publishing Corporation.788 BOOK REVIEWS [Analyst, Vol. 92 The chapters are largely devoted to inorganic chemistry (in the broad sense), under such headings as Atomic Structure, Chemical Bonding, Chemical Equations and Quantitative Relation- ships, Electrochemistry, Elements of Chemical Thermodynamics, Chemical Kinetics and Chemical Equilibrium, Ionic Equilibria, Metals and Complex Compounds. Subjects covered in the 42-page chapter on Organic Chemistry range from Alkanes to Polymers, and the final chapter, Chapter 18, Nuclear Chemistry, takes up 23 pages. For the advanced student, or anyone needing a refresher, this book should provide an excellent companion to textbooks that cover the individual fields in much more detail.W. T. ELWELL DIE ORGANISCHE CHEMIE DBS ZINNS. By PROF. DR. WILHELM P. NEUMANN. Pp. xii + 232. Stuttgart: Ferdinand Enke Verlag. 1967. Price (paper) DXI 65.50; (linen) DM 69. Between 1852, the year of the first publication describing an organotin compound, and 1935, fewer than 200 papers appeared on this subject, and all of the then known information could be contained in 60 pages of the book on organometallic compounds published by Krause and Grosse in 1937. In the last 30 years, however, well over 3000 publications have appeared, and this increase in the interest in organotin chemistry may be said to have started, in the early 1950’~~ with the researches of Van der Kerk and his co-workers in Holland. At first the main emphasis was on methods of preparation, but, later, with the developments in the chemistry of the tin - hydrogen bond, interest shifted to the study of reaction mechanisms, and it is this aspect of organotin chemistry that has mainly interested Professor Neumann.Since 1959, he has been leading an active team of investigators a t the University of Giessen, and has published numerous papers in this time. He has now written an excellent concise account of the whole field of organotin chemistry, although naturally the main emphasis, more than a third of the book, is concerned with the organotin hydrides and their reactions. In particular, he gives a detailed account of the two important subjects of hydrostannation, viz., the addition of organotin hydrides to double and triple bonds, with the formation of tin - carbon bonds; and hydrostannolysis, their reductive cleavage of alkyl halides and of tin - element bonds, and their reaction with acids, bases and inorganic halides, both fields in which he himself has made important contributions.This latter class of reactions can cover such a large variety of compounds that it is possible that the most important use of organotin compounds in the future may be as inter- mediates in organic synthesis rather than as stabilisers or biocides. A short, 4-page summary is given of analytical methods including the chromatographic and chemical procedures available for the separation and determination of the different types oi organotin compounds, and this is followed by a useful table of infrared and Raman absorption bands, and their assignations. In a chapter on the technology of organotin compounds, the available methods of manu- facture are mentioned ; the industrial use of the dialkyltin compounds as stabilisers and the biocida applications of the tri-alkyl and tri-aryl compounds are briefly discussed. There is also an accouni of the published work on the toxicology of these compounds. The book concludes with a selectei bibliography of over 900 items, most of them references to work published within the last 7 years J. W. PRICE M~~THODES D’ANALYSE CETAICIA---1966. MBTHODES 15 1 k 200. COMMISSARIAT A L’6:NERGII ATOMIQUE ET COMMISSION D’ETABLISSEMEXT DES M~THODES D’ANALYSE. Parte 3. Pp.v + 285. Paris: Presses Universitaires de France. 1966. Price 76F. This volume brings up to date the methods of analysis accepted by the French Atomic Energ! Commission. A further 50 methods are now described, which are principally concerned with th application of known procedures to the technical problems associated with the analysis of nuclea materials. As such, it contains little of particular interest to the analyst who is not concernec with such materials, and little by way of novelty to those who are. W. I. STEPHEN

ISSN:0003-2654    

DOI:10.1039/AN9679200783

出版商:RSC    

年代:1967

数据来源: RSC

摘要:

788 BOOK REVIEWS [Analyst, Vol. 92 Erratum NOVEMBER (1967) ISSUE, p. 688, 3rd line above Table I. For “1.003 €or iron(II1)” read “0.99‘ for iron(II1)”.

ISSN:0003-2654    

DOI:10.1039/AN9679200788

出版商:RSC    

年代:1967

数据来源: RSC