摘要:

Proceedings of the Society for Analytical Chemistry CONTENTS Report of Meeting .. . . 139 Papers accepted for The Analyst I39 "Research Topics in Analytical Chemistry" .. .. .. 140 Membership changes . . . . 152 Publications Received . . .. 152 Notices .. .. .. .. 154 Proc. SOC. Analyt. Chem. VoI. 3 No. 9 Pages 139-154 Forthcoming Meetings . . Back Cover September 1966 Vol. 3 No. 9 PROCEEDINGS September I966 OF THE SOCIETY FOR ANALYTICAL CHEMISTRY President of the Society A. A. Smales O.B.E. Hon. Secretury of the Society S. A. Price Hon. Treasurer of the Society D. T. Lewis C.B. Hon. Assistant Secretaries of the Society B. S. Cooper; D. W. Wilson Secretary Miss P. E. Hutchinson 14 BELGRAVE SQUARE LONDON S.W.1 Telephone BELgravia 3258 Editor 1. B. Attrill Proceedings is published by The Society for Analytical Chemistry and distributed t o members and all subscribers t o The Analyst without charge Single copies may be obtained direct from the Secretary The Society for Analytical Chemistry a t the above address (NOT through Trade Agents) price 2s.6d. post free. Remittances payable t o “Society for Analytical Chemistry” MUST accompany orders Determination of Trace Elements with Special Reference t o Fertilisers and Feeding Stuffs A Report of the Analytical Methods Committee Recommended methods for determining traces of- B Ca CI- Cr Co Cu F I Fe Mg Mn No Ni Se Zn Pp. viii + 39 21s. net ~ ~ _ _ ~ Members of the Society for Analytical Chemistry are entitled t o buy copies a t the special Members’ price of 12s. 6d. provided they order direct from The Editor The Analyst 14 Belgrave Square London S.W.1 must accompany Members’ orders Remittances made out t o “Society for Analytical Chemistry” Published for the Society for Analytical Chemistry W. HEFFER AND SONS LTD. PETTY CURY CAMBRIDGE by

ISSN:0037-9697    

DOI:10.1039/SA96603FX027

出版商:RSC    

年代:1966

数据来源: RSC

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~~ ~~ Forthcoming Meetings-continued October Thursday 20th “Recent Developments in the Determination of Small Amounts of Fluoride,” by R. J. Hall F.I.M.L.T. Lecture Theatre Civic College Ipswich; 2.15 p.m. (This meeting has been arranged in East Anglia to explore the possibility of setting up an East Anglia Section of the Society. Members and visitors who might be interested in such a Section are asked to attend this meeting to express their views.) MIDLANDS SECTION jointly with the Polarographic Society Discussion Meeting on “Organic Polarography. ” Speakers Mrs. B. Lamb B.Sc. F.R.I.C. G. F. Reynolds M.Sc. Ph.D. M.R.S.H. F.R.I.C. and C. H. Ruddle. Spread Eagle Hotel Nottingham; 6 p.m. “Use of Enzymes in Biochemical Analysis,” by I. D. Fleming Ph.D. A.R.I.C. Meeting Room of the Pharmaceutical Society 17 Bloomsbury Square London IPSWICH Tuesday 25th NOTTINGH AM Thursday 27th BIOLOGICAL METHODS GROUP.LONDON W.C.l; 7 p.m. Friday 28th SCOTTISH SECTION. GLASGOW “Detection and Identification of ‘Dope’,” by M. S. Moss M.Sc. F.R.I.C. University of Strathclyde Glasgow; 6 p.m. THE SOCIETY FOR ANALYTICAL CHEMISTRY Forthcoming Meetings September Tuesday 20th LONDON Wednesday 21st BIRMINGHAM Wednesday 21st DURHAM Friday 23rd GLASGOW Thursday 29th CHESTER October Saturday 1st LIVERPOOL Wednesday 5th LONDON Wednesday 19th LONDON Thursday 20th IPSWICH SPECIAL TECHNIQUES GROUP 2 1st Anniversary Meeting and Dinner. “Special Techniques Past Present and Future,” by R. C. Chirnside F.R.I.C. Lecture Theatre Laboratory of the Government Chemist Cornwall House Dinner-Members’ Dining Room House of Commons London S.W.1 ; Stamford Street London S.E.l; 3 p.m. 6.30 p.m. Midlands Section jointly with the Birmingham and Midlands Section of the “Some Aspects of the Polarography of Unsaturated Aliphatic Acids,” by M. L. “Some Aspects of the Analytical Chemistry of Soil Humic Acids and Related “The Determination of Citric Acid,” by A. R. Witty B.Sc. A.R.I.C. Hasworth Lecture Theatre Chemistry Department The University Edg- Society of Chemical Industry on “Determination of Organic Acids.’’ Richardson A.C.T. A.R.I.C. and P. E. Luton L.R.I.C. Synthetic Materials,” by J . M. Thompson M.Sc. baston Birmingham 15; 3 p.m. NORTH EAST SECTION. “Some Recent Developments in Absorption Spectrometry Molecular and Atomic Flourescence,” by Professor T. S. West Ph.D. D.Sc. F.R.I.C.The University Durham; 6.30 p.m. SCOTTISH SECTION. “The Initiation Development and Testing of Analytical Methods in Industry,” University of Strathclyde Glasgow; 6 p.m. ATOMIC-ABSORPTION SPECTROSCOPY GROUP. “Fluorescence of Metal Atoms in Flames,” by D. J . Jenkins. “High Temperature Flames,” by W. Slavin. Thornton Research Centre Chester ; 10 a.m. by J. Haslam D.Sc. F.R.I.C. NORTH OF ENGLAND SECTION. “Organochlorine Pesticide Residue Analysis,” by J. O’G. Tatton M.Sc. Lecture Theatre City Laboratories Mount Pleasant Liverpool ; 2.30 p.m. F.R.I.C. SOCIETY. “Some Recent Developments in Inorganic Analysis on the Microgram Scale,” Meeting Room of the Royal Society Burlington House Piccadilly London by Professor C. L. Wilson Ph.D. D.Sc. M.R.I.A. F.R.I.C. F.I.C.I. W.l.; 7 p.m. MICROCHEMICAL METHODS GROUP London Discussion Meeting. Discussion on “The Determination of Zinc.” “The Feathers,” Tudor Street London E.C.4; 6.34) p.m. MIDLANDSECTION on “Aspects of Trace Analysis.” “The Determination of Some Organophosphorus Pesticides in Biological “The Estimation of Trace Volatiles in Whisky by Gas Chromatography,” by Material,” by J . S. Leahy MA. C. Macfarlane A.C.T.(Birm.) A.R.I.C. Continued inside back covey Printed by W Heffer & Sons Ltd Cambridge England

ISSN:0037-9697    

DOI:10.1039/SA96603BX029

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

September 1966 PROCEEDINGS OF THE SOCIETY FOR ANALYTICAL CHEMISTRY Vol. 3 No. 9 Report of Meeting MIDLANDS SECTION AND PARTICLE SIZE ANALYSIS GROUP A JOINT Meeting of the Midlands Section and the Particle Size Analysis Group was held at 6 p.m. on Wednesday June 8th 1966 in the Chemistry Department The University Edg- baston Birmingham 15. The Chair was taken by the Chairman of the Midlands Section Mr. W. T. Elwell F.R.I.C. The subject of the meeting was “Commercial Apparatus for Surface Area Measurement” and the following papers were presented and discussed “The Perkin-Elmer - Shell Soryto- meter,” by G. A. Lombard; “The Strohlein Areameter,” by D. P. Bryant; “The Numinco - On- Surface Area - Pore Volume Analyser,” by A. G. Cottrell. Papers Accepted for Publication in The Analyst THE following papers have been accepted for publication in The Analyst and are expected to appear in the near future.“The Application of the Oxygen-flask Technique to the Determination of Trace Amounts of Chlorine and Sulphur in Organic Compounds,” by R. McGillivray and S. C. Woodger “Determination of Metallic Complexes of Nitrated Secondary Amines,” by €3. R. Savage J. B. Butt and J. A. Tallmadge. “The Determination of 4-Aminobiphenyl in Aromatic Amines,” by 0. Norman and G. A. Vaughan. “Spectrophotometric Determination of Dibenzolylmethanes in some Dibenzoylmethides,” by S. Incitti and A. La Ginestra. “The Determination of Benzylpenicillin Traces in Propyliodone Injection B.P. ,” by D. J. Simmons and J. P. Jefferies. “The Determination of Niobium in Metals and Alloys,” by A. I. Williams.“Excitation Gradients in Acetylene - Oxygen Flames,” by J. A. Dean and J. E. Adkins. “The Determination of Nickel with Dimethylglyoxime in Iron and Steel containing “The Detection of Nitrate in the Presence of Interfering Substances,” by H. M. Stevens. “The use of 8-Hydroxyquinoline for the Separation of Yttrium-90 in the Determination of Strontium-90 in Biological Materials,” by J. D. Burton R. M. Love and E. R. Mercer. “Detection of o-Hydroxy and o-Methoxy Estrogens by means of a Modified Folin - Ciocalteu Test,” by A. M. Gawienowski and R. L. Risacher. “The Colorimetric Determination of Boron in Soils Sediments and Rocks with Methylene Blue,” by R. E. Stanton and A. J. McDonald. “Determination of Molybdenum in Niobium and Tantalum by Atomic-absorption Spectroscopy,” by G. F. Kirkbright M. K. Peters and T. S. West. “On the Determination of Diquat Residues in Potato Tubers,” by W. J. Kirsten. “A Modified Potentiostat for Controlled Potential Analysis,” by J. Grimshaw and R. K Cobalt and Copper,” by A. Claassen and L. Bastings. Quigg.

ISSN:0037-9697    

DOI:10.1039/SA9660300139

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

140 RESEARCH TOPICS IN ANALYTICAL CHEMISTRY [Proc. SOC. AnaZyt. Chenz. Research Topics in Analytical Chemistry Some Current Work in Universities and Colleges of Advanced Technology The following are summaries of papers presented at the Ordinary Meeting of the Society held on May 4th 1966 and reported in the May issue of Proceediqzgs (p. 69). Some Aspects of Titrimetry on the Microgram Scale BY C. L. GRAHAM AND CECIL L. WILSON (Queen’s University Belfast) DR. GRAHAM described an assembly by which 1-p1 aliquots could be titrated potentiometrically. The burette resembled that described by Wigglesworth (Biochem. J. 1937,31 1719) and was constructed from standard borosilicate tubing. The burette was not perfectly uniform. About 25 cm of the capillary portion was calibrated in equal-volume increments.The position of the titrant meniscus was controlled by a water-filled Agla micrometer syringe outfit. The capacity of the burette could vary from 0-5 to 5 p1. Seven-nanolitre increments could be dispensed. The entire titration unit was mounted horizontally on a modified Prior manipulator. The pipettes were in many ways similar to the burette but delivery of liquid was coiitrolled also hydrodynamically by ;I manually operated Fortuna syringe. The pipette - syringe unit was mounted on a simple rack-and-pinion device which permitted the pipette t o be manoeuvred in three dimensions. Calibrated vessels (of 0.200-ml capacity) were constructed from transparent quartz. Microgram amounts of sample were weighed out on an Oertling QOl decimicro balance. Dissolution was carried out in the calibrated vessel which could be heated if necessary.Equivalence points were detected potentiometrically. A bi-metallic electrode pair was used. The liquid to be titrated was contained in a flat-bottomed titration vessel (5 to 7-p1 capacity) mounted horizontally in a Perspex moist chamber. The solution was agitated by impinging a jet of pressurised carbon dioxide on to the surface of the liquid. The capacities of the pipette and burette were determined spectrophotometrically with an aqueous solution of nicotinamide (0-5 M). A new radiometric procedure involving the use of manganese-56 solution for the calibration of microlitre and sub-microlitre pipettes was outlined. The volumetric vessel was calibrated gravimetrically. DISCUSSION MR. J. M. CARTER asked what the standard deviation of the pipettes and burettes used was; if the liquid film left after the liquid had been measured caused any trouble; and were microscopes used to line up the meniscus? Dr.Graham replied that the pipettes like the burettes titration vessels and calibrated vessels were treated with a silicone fluid to make the interior surfaces water repellent. Whether or not a lens or even a more elaborate optical system should be used when aligning the meniscus with a particular graduation on the pipette was determined by the volume it was intended to dispense. If the volume was about 1 pl it was not necessary to use a lens; for smaller volumes optical assistance of one sort or another was preferable. A microscope was best avoided unless the volume to be measured was about 50 nanolitres or less.The coefficient of variation associated with the spectrophotometric determination of the volume of a 1-pl pipette was 0.6 to 1 per cent. (depending on the dimensions of the pipette). On the microgram scale this apparently high value was quite acceptable because the precision with which other operations could be carried out during a titration was often more significant. Some Developments in the Use of Oximes as Analytical Reagents BY C. BROUGHTON ( Uitizicwity of Birvninghanz Edgbaston Birmingham 15) MR BROUGHTOX said that the oximation of cz-diketones resulting in the formation of dioximes which exhibited geometrical isomerism had long been known. The work which he was to describe concerned the preparation separation and identification of pure isomeric dioximes September 19661 RESEARCH TOPICS I N ANALYTICAL CHEMISTRY 141 from such oximations and the metal complexes formed by these dioximes.Techniques such as thin-layer chromatography and infrared and nuclear magnetic resonance spectroscopy had been used in an effort to resolve the many problems involved. The oximation of furil with hydroxylammoniuin chloride in refluxing ethanol was monitored by using thin-layer chromatography ; this showed that the oximation proceeded by way of the monoximes which were further oximated to give the a and y-dioximes. Up to the present time it had not been possible to detect the p- or syn-dioxime and all attempts to prepare this particular isomer resulted in the formation of either a mixed a-y-dioxime or unresolvable tars. The use of a-furildioxime as a reagent for nickel(I1) instead of dimethylglyoxime was first recommended by Soule in 1925 mainly on the basis of its much greater aqueous solubility.However new solubility measurements on chromatographically pure isomers indicated that the solubility of a-furildioxime in water was less than that of dimethylglyoxime. Commercially available a-furildioxime was generally a mixture of approximately equal amounts of a and y-furildioximes. It was now shown that the y-isomer did not react with nicltel(I1) under the usual conditions for this precipitation and this explained why at least twice the stoicheiometric amount of the oxime was required for the precipitation of nickel(I1) as the a-furildioximate. The reaction of y-furildioxime with nickel(I1) in ammonia - am- monium chloride buffered medium did not result in the precipitation of nickel-y-furildioximate but if the mixture was irradiated with ultraviolet light isomerism to the a-form resulted and precipitation of nickel-cx-furildioximate occurred.This procedure was essentially one of precipitation from homogeneous solution but it had not been studied further because irradiation resulted in considerable breakdown of the oxime molecule. The oximation of benzil under various conditions led. to the isolation of the three expected isomeric dioximes. By means of nuclear magnetic resonance techniques absolute con- figurations had been assigned to the three isomers. These configurations of the molecular structure were in complete agreement with those proposed in the literature and derived from the metal-complexing reactions which the isomers did or did not undergo.The extremely low solubility of a-benzildioxime in both ethanol and water precluded its use as a quantitative gravimetric reagent for nicltel(I1). A series of pyridylpheiiyldioximes was synthesised in which the hetero-atom was moved progressively away from the centre of chelation. The presence of this heterocyclic ring in the dioxime resulted in an increase in the solubility of the dioxime in water but complicated the reactions by providing another centre at which chelation could occur. The four theoretically possible isomers of each unsym- metrical dioxime had been detected and work had begun on the assignment of configurations to these isomers. This was to be followed by a study of the metal complexes which these isomers formed with some of the transition metals.DISCUSSION MR. I,. S. BARK asked about the loading of the thin-layer plates in the separation of the oxime isomers; and for information about the naturc of the eluent. Mr. Broughton replied that 5 to 10 pg of oximcs were applied to the layer in 5 to 10 p1 of solvent. The eluting solvent was bcnzene - tetrahydrofuran - chloroform (80 + 15 + 5 by volume). In answer to MR. G. DUNCAN’S question about the conditions of the thin-layer chromato- graphic expcrirnents with respect to eluents sample loadings and reproducibility of results Mr. Broughton said that he had used silica gel G (Stahl) as the adsorbent. The tank atmosphere was pre-saturated with solvent vapour by lining the walls of the tank with filter-paper. Isomerisa- tion had not been noted during the chromatography of any of the oximes that he had investigated.DR. D. BETTERIDGE asked what the object was in putting another co-ordinating site adjacent to the centre of co-ordination of a specific reagent; and if any of the synthesised reagents pre- cipitated other metal ions or was the unique crystal structure of nickel dimethylglyoxime retained. Mi-. Broughton said that he was interested in the concept o€ bifunctionality applied to organic analytical reagents. Preliminary investigations had shown that several metal ions were precipitated by these oximes and he and his colleagues hoped to investigate these reactions in the near future. MR. W. A. STUART asked if benzene - pyridine dioximes had been considered as colorimetric reagents for rnctals by solvent extraction of their complexes. Iclr.Broughton hoped to look at this possibility although he thought that the presence of a nitrogen atom iii the molecule when 142 RESEARCH TOPICS IN ANALYTICAL CHEMISTRY [Proc. SOC. Analyt. Chew. not involved in chelation might preclude the completc solvent extraction of the complex because of its protonation a t lower pH values. MR. E. BISHOP asked whether the green dioximates had been encountered in the present work and whether their structure had been confirmed. Mr. Broughton replied that the green insoluble non-extractable 1 1 nickel(I1) complexes formed by y-(amphi) dioxinies had been noted but he had not investigated their structure. They were believed to be polymers. Continuous SubstoicEreioinetric Analysis BY B. G. COORSEY (The Univevsity of Aston in Bivnzinghain Gosfn Green Birnzinghanz 14) MR.COOKSEY said that substoicheiometry (J. RfiiiClta and J. Stary Atom. Energy Rev. 1964 2 No. 4) was a radiochemical technique that improved the sensitivity of trace metal analysis by solvent extraction procedures. The basis of the technique was the use of a smaller amount of reagent than the stoicheiometric amount required by the metal. In this way the same amount of metal was always extracted. This was convenient in isotope dilution analysis because the activity of the organic phase was then directly proportional to the specific activity of the metal and it was not necessary to measure the amount of metal extracted. Under these conditions the full sensitivity of radioactive tracer techniques was realised. This could be illustrated by determining mercury by extraction as the dithizonate as reported by J.RbiiEka and J. Star? (TaZanta 1961 8 535). By using modern scintillation counters very small amounts of this isotope could be detected and therefore very small amounts of mercury could be determined. Thus 0.001 pg of the commercially available mercury isotope had an activity equal to the background. This should be compared with the colorimetric method where 1 pg would be needed to obtain a comparable accuracy. The selectivity of the method was also improved because there was no excess of dithizone to react with interfering metals. For example when excess of dithizone was used copper was extracted quantitatively from 0.1 N sulphuric acid but in the substoicheiometric method copper did not interfere. Mercury formed a strong complex with dithizone and copper was incapable of displacing mercury from mercury dithizonate.Small amounts of metals were often adsorbed on the walls of glass vessels thus preventing the quantitative recovery needed by conventional procedures. This did not affect the substoicheiometric method providing that enough mercury remained to react with all of the dithizone. The greatest disadvantage of the substoicheiometric method was the need for a separate radiochemical laboratory; this however could be avoided by automating the process. At the same time rapid analyses independent of operator bias were achieved. Technicon instruments had already automated the solvent extraction procedure in which a peristaltic pump drove the sample and dithizone solutions through a mixing coil where extraction occurred.The two layers were separated and the organic layer was drawn through the flow cell of a colorimeter the output of which drove a pen recorder. In the radiochemical method the sample and labelled mercury solutions were mixed in the first coil dithizone solution was added and the extraction and separation carried out as before. The sensitivity was high; Sin1 of a 0.01-p.p.m. solution could be analysed with a standard deviation of 5 per cent. The sample could have any acidity between 0.03 and 3 N with respect to nitric acid or sul- phuric acid. The machine was used to investigate 58 chemicals for possible interference and results were as shown in Table I. The interference of strong oxidising agents and strong reduchg agents could be prevented by adding hydrogen peroxide.Mr. Cooksey and his colleagues were investigating methods of overcoming the ifiterference of halides which were the only anjons to give serious interference. Mercury-203 emitted a gamma-ray with an energy of 0.2 MeV. Another advantage lay in the insensitivity to adsorption problems. The colorimeter was replaced by a scintillation counter and rate-meter. With this apparatus 10 samples per hour could be analysed. September 19661 RESEARCH TOPICS I N ANALYTICAL CHEMISTRY Chloride interfered by a strange mechanism; it formed a tertiary complex- Hg2+ + C1- + H2Dz + HgClHDz + H+ 143 so that twice as much mercury was extracted by the dithizone from chloride solutions as from nitrate solutions where primary mercury dithizonate was formed- Hg2+ + 2H2Dz -+ Hg(HDz) + 2H+ This did not occur in conventional analysis because free dithizone destroyed the chloro- complex- HgClHDz + H,Dz -+ Hg(HDz) + HC1 It could be used for any element providing a suitable isotope was available having a moderate half- life say 3 hours and having a high specific activity say 10 mC per g; and that there was a suitable method of analysis in which the element formed a strong easily extractable complex with the reagent.Several metals had been determined manually by these procedures iron by extraction as cupierrate ; copper as diethyldithiocarbamate from EDTA solutions; zinc as the dithizonate from solutions containing ethanolaminedithiocarbamate. Experience with mercury showed that these methods should be easily adaptable to continuous analysis. The substoicheiometric principle of course was not confined to mercury.TABLE I RESULTS OF INVESTIGATIONS INTO POSSIBLE INTERFERENCE FROM VARIOUS CHEMICALS Substances that interfere 7 _-A_-- -_- 7-- by competing by with by by reducing by forming Substances that do not for the the the mercury tertiary mercury oxidising complexing the interfere dithizone dithizone mercury to mctal complexes NH4+ Se4+ SO4,- Au3+ MnO,- CN- Sn2+ c1- Mg2+ Cr3+ H,PO c10,- BaZ+ Fez+ tartrate Ag+* F- I<+ Te4+ Clop- I’d2+ Crz0,2- SCN- N,H,+ Br- Na+ TI+ CH,COO- Pt2+ NO,- I- HP0,- Ca2+ Mn2+ citrate Pt4+* Ce4+ Sz032- AP+ Fe3+ oxalate Bi3t* EDTA Ga3+ Co2+ borate 1n3+ Ni”+ molybdate Ce3+ Cu2+ H,O ~ 1 1 4 + Zn2+ S20,2- Sb3 J. Pb’+ Be2+ RsJ 1 NO,- * If present in excess of 100 p.p.m. DISCUSSION Mr. BARK asked if it was possible to overcome the interference of chloride in the formation of the mercury dithizonate complex (forming a 1 1 1 mercury - chloride - dithizone complex) by loading the solution with chloride to ensure complete formation of the latter complex whose concentration could then be measured.Mr. Cooksey replied that a large excess of mercury was required as well as a large excess of chloride to ensure the complete conversion of dithizone to this complex. This lowered the sensitivity by a factor of 1000 and the most important advantage of substoicheiometry was lost. Precise Coulometric Titration BY M. RILEY AND E. BISHOP (Department of Chemistry University of Exeter) MR. RILEY said that the high precision that could be achieved by using the constant-current coulometric titration technique had been demonstrated several times in recent years.Standard deviations of the order of 50 p.p.m. had been obtained for the determination of acids (J. K. 144 RESEARCH TOPICS IN ANALYTICAL CHEMISTRY [Proc. SOC. AnaZyt. Chem. Taylor and S. W. Smith J . Xes. Natiz. BUY. Stand. 1959,63A 153; E. L. Eckfeldt and E. W. Shaffer jun. AnaZyt. Ckzewz. 1965 37 1534) halides (G. Marinenko and J. K. Taylor J . Xes. Natn. Bur. Stand. 1863 67A 31) and potassium dichromate (R. G. Monk and G. C. Goode [by differential titration with 2 cells in series] TaZanta 1963 10 51; G. Marineillto and J. K. Taylor J . Xes. Natn. BUY. Stand. 1963 67A 453). Although such results should encourage the adoption of the technique for standardisation purposes titration cells generally had been complex often having four separate compartments and currents were only about 100 mA and were often manually controlled.Work in progress on the coulometric titration of acids was directed to the use of currents up to 2 amps with a simple undivided cell. The deposition of silver bromide on a silver anode was studied as an auxiliary electrode system for this purpose. It had been shown that the ohmic resistance of the titration cell rose steadily as electrolysis proceeded until the silver bromide film reached a limiting thickness ; at this point the resistance rose sharply to a high value indicating that the film became non-porous and that efficient discharge of bromide ion was no longer possible. This limiting thickness appeared to be approximately inversely proportional to current density; at 10 mA per cm2 and a bromide concentration of 0.3 M it was equivalent to about 1G coulombs per cm2.At low bromide concentrations e.g. 0.05 M and high current densities e.g. 40 mA per cm2 breakdown of the film soon occurred and both anodic and cathodic current efficiencies were reduced. The area of the silver anode should be as large as conveniently possible; in addition the bromide concentration should be as low as possible to minimise the dissolution of silver bromide but large enough to depolarise the anode efficiently throughout the titration. A Solartron AS.411 power unit had been used to supply currents up to 2 amps and con- stancy of the order of 50 p.p.m. was obtained under favourable conditions. Attempts had been made to use operational amplifiers to compensate for variations in the output of this unit by adding a proportional correction current into the cell circuit but satisfactory control action had not yet been achieved.Other applications of operational amplifiers investigated included a source of readily adjustable reference voltage and a 2-amplifier constant-current supply based on such a voltage source; in both cases currents of up to 10 to 12 mA could be supplied and constancy of the order of 10p.p.m. achieved. The operational amplifier con- stant-current supply could be used in differential coulometric titration for the final deter- mination of the small difference between the amount of a sample in one cell and the amount of an accurately known standard in a second cell. DISCUSSION MR. G. PHILLIPS asked if Mr. Riley had considered expending less effort on standardising the current and more on measuring the mean value of the current during electrolysis; for example by using a digital voltmeter this could be measured many times per second and an accurate mean value obtained.In reply Mr. Riley said that it was true that precision of the order of 50 p.p.ni. could be achieved by the alternative approach of integration to determine the number of coulombs used when the current was not constant if a high quality digital voltmeter was used. Such instruments were expensive and there was still a need for a relatively cheap mains-operated constant-current supply capable of high precision and either readily available or easily assembled from readily available components. A New Fluorimetric Reagent for the Determination of Submicrogram Amounts of Magnesium BY R. SMITH (C?Lewaistvy Department Iwzpevial College London S .W.7) MR. SMITH said that a series of 15 mono- and bis-salicylidene Schiff bases had been prepared and examined as potential reagents for the spectrofluorimetric determination of magnesium in aqueous or semi-aqueous solution. Almost all of the Schiff bases reacted to give fluorescent magnesium complexes in alkaline solution but many of the reagents themselves hydrolysed to give fluorescent products. NN’-bis-salicylidene-2,3-diamiiiobenzofuran (SABF) however appeared to undergo hydrolysis very slowly to give products with a fluorescence emission September 19661 RESEARCH TOPICS IN ANALYTICAL CHEMISTRY 145 maximum at 470 mp. The magnesium - SABF complex had a fluorescence emission maxi- mum a t 545 mp and an excitation maximum at 475 mp and therefore the reagent hydrolysis did not affect the intensity of fluorescence of the complex.SABF was then compared with NN’-bis-salicylidene ethylenediamine which had been proposed by Cuttitta and White as a reagent for determining magnesium in dimethylformamide solution. Because of the various steric interactions in SABF the molecule approximated to a rigid cage into which the chelated metal ions could fit. Stuart models indicated that only metal ions with a radius of less than lk could undergo chelation; this was confirmed by experiment. While NN’-bis-salicylidene ethylenediamine gave strongly fluorescent com- plexes with aluminium beryllium gallium indium magnesium and zinc SABF gave strong fluorescence only with gallium (at pH 5) and magnesium (at pH 10.5). SABF could be used either in a 50 per cent.methanol - water solution or could be extracted into isobutyl methyl ketone. When used in 50 per cent. methanol the reaction was sensitive to 0-05 pg of magnesium in 50 ml of solution Calcium which formed a coloured non-fluorescent complex could be tolerated in 10-fold molar excess and in the presence of strontium - EDTA a 200-fold molar excess of calcium could be tolerated. The extraction procedure involved the use of isobutyl methyl ketone as the organic phase and 3ml of a 2 to 1 pyridine - diethylamine buffer solution giving a pH of 12.4. The extraction was quan- titative at the 0.2 1 and 2-pg levels. Calcium could be tolerated in 2000-fold molar excess if strontium - EDTA was present. The 50 per cent. methanol procedure was applied to the analysis of magnesium in blood serum.Only 50 p1 of sample were taken and were eventually diluted to 50 ml. Because of the small sample size no pre-treatment was necessary. The results of repetitive deter- minations on 14 different samples were given. The method was also applied to the determina- tion of magnesium in drinking water with 0.25ml of samples containing 1 to 48 p.p.m. of magnesium. The results of repetitive determinations on 9 samples were shown to be in good agreement with results obtained by flame photometry. Mr. Smith thanked Dr. R. M. Dagnall and Professor T. S. West for supervision of the work presented in the paper and also Dr. J. E. Baldwin for supervision of the structural determination of SABF. p.p.m.). DISCUSSION DR. BETTERIDGE asked whether the extraction of magnesium was very dependent on the pH and would the magnesium be extracted at pH 12 if other buffer systems were used or was the diethylamine - pyridine essential to the extraction as for example amines were in the extraction of magnesium 8-hydroxyquinolinate? Mr.Smith replied that at pH values 10 to 12 obtained by adding hydrochloric acid to the buffer incomplete extraction occurred. Pyridine was necessary in the buffer to permit extraction of the magnesium - SABF complex although diethylamine appeared to act only as a strong base. It was assumed that pyridine replaced the hydroxyl group in the co-ordination sphere of the magnesium - SABF complex in a similar manner to that proposed for ainines in the extraction of magnesium 8-hydroxyquinolinate. MR. M. L. RICHARDSON asked for further details of the effects of anions phosphates and organic acids especially citric acid on the determination of magnesium with this reaction.Mr. Smith replied that simple anions e.g. acetate halide nitrate cyanide sulphate persulphate and many metallic anions e.g. chromate molybdate and germanate did not interfere when present in 100-fold molar excess over magnesium. Similar excesses of phosphate reduced the intensity of the fluorescence by 50 per cent. while oxalic citric and tartaric acids and also complexones such as EDTA reduced the fluorescence intensity to below the blank value. Chromatography of Some First and Second Row Transition Metals on Thin Layers of Substrates Impregnated with Tributyl Phosphate BY G. DUNCAN L. S. BARK AND R. J. T. GRAH~N (Royal College of Advanced Technology Salfovd Lancs.) MR.DUNCAN said that as the well known metal extractant tributyl phosphate (TBP) was a non-volatile water-immiscible liquid it was ideally suited as an impregnant for the reversed- phase thin-layer chromatography of metal ions. The resulting system was similar to liquid - 146 RESEARCH TOPICS IN ANALYTICAL CHEMISTRY [Proc. SOC. Analyt. Chem. liquid extraction and therefore a relationship could be expected between the RF value of a metal ion and its partition coefficient in the corresponding liquid - liquid extraction system. The speaker had carried out some investigations into the effect of the loading of the TBP on the layers; pre-treatment of the TBP with the eluent acid (1 to 9 M hydrochloric acid) ; the nature of the support material; and the concentration of hydrochloric acid in the mobile phase on the R values of the metal ions chromatographed.The appropriate substrates (cellulose MN 300HR MN-Kieselgel N-HR) were slurried with a solution of TBP in carbon tetrachloride (2.5 to 20 per cent.) spread on to the plates (20 x 20 cm) and dried leaving the TBP impregnated uniformly 011 the layer. Five micro- grams of each metal ion were applied to the layer which was then eluted with hydrochloric acid in a specially designed saturation chamber. By strict standardisation and control of the chromatographic conditions highly reproducible results could be achieved (&-0.02 R units). Mr. Duncan’s investigations showed that the maximum loading (5 per cent. solution) of TBP on cellulose layers was approximately twice that of the silica-gel layers ; exceeding the maximum loadings resulted in the formation of 2 eluent fronts the lower of which was uneven and caused distortion of the spots especially with eluents of high acid concentration.Pre- treatment of the TBP with eluent acid gave RF values within the experimental tolerances of &Om02 and so pre-treatment was not considered necessary. RF values were generally higher on TBP - silica gel layers than on corresponding TBP - cellulose layers but on both layers the order of RF values was the same and the R values generally decreased with increased acid concentration. It was suggested that the double-front formation in these reversed-phase systems was caused by overloading of the layers resulting in the eluent acting as a “molecular snow- plough,” sweeping the excess of TBP off the layers.The better TBP-retention properties of the cellulose could be explained in terms of the more open nature of the cellulose particle which formed hydrogen bonds more readily than silica gel with the TBP. The view was substantiated by some runs made on a crystalline grade of cellulose (Chromedia CC41) which had weak adsorption properties and none of the swelling properties of conventional cellulose. This system was even more prone to double-front formation than was the silica-gel system. DISCUSSION DR. G. NICKLESS asked how an R value was measured to f0.02; and how reproducible the RF values were even when applying standardised techniques because of variations in the quality of different batches of manufacturers’ material for thin-layer chromatography. He suggested that by putting some of the thin-layer chromatographic layer on the top of a gas- chromatographic column Mr.Duncan could find whether the tributyl phosphate was being washed to the front. Mr. Duncan replied that the R values quoted were the averages of at least 4 deter- minations each within k0.02 I? units of the mean value. He and his colleagues had used the centre of spot density estimated visually as the point to which measurement was made. He thought that for a length of development of 12.5 cm (which was used by him) a spot of length 1.5 cm (the maximum length he accepted) for a spot of R value 0-5 units the allowable error for judging the centre of spot density was h2.5 mm. He regarded it as improbable that their estimation of the centre of spot density was outside these limits.Any variations in R values caused by variations in the materials used were found to be within the experimental limits of k0.02 units. On occasions when the work had been repeated by each of the other worlters the mean R values were in agreement with those quoted. The suggestion that the upper layer could be identified by gas chromatography was valid. However Mr. Duncan felt that the experimental evidence was sufficient to indicate that it was TBP that was washed off the layers. Plates which showed double fronting were “dried” by heating at 110” C for 20 minutes; the area between the two fronts was still wet although that below the lower front appeared dry. The wet area smelled strongly of TBP and not of hydrochloric acid. TBP was the only high boiling liquid present originally-it was therefore evident that it was TBP that remained.September 19661 RESEARCH TOPICS I N ANALYTICAL CHEMISTRY Some New Inorganic Ion Exchangers BY G. N. STRADLING (Depavtvnent of Chevnistry Univemity College of Swansea Glamorgun) 147 MR. SrRADLING said that it had been known for some time that heavy-metal hexacyano- ferrates(I1) formed a group of compounds that could incorporate alkali-metal ions into their crystal lattices. In the search for new inorganic ion exchangers therefore such complexes presented a possibility for the isolation and separation of the alkali metals. Intrinsically they possessed the significant advantages of being cheap easily prepared and having low solubility in acidic neutral and basic media. A. S. Kozlov ("Metody Analiza Redkikh i Isvetnylth Metal Moscow," Gosudarst University in M.V. Lomohosova 1956 p. 71; Chem. Abstr. 1959,53 13877h) had attempted to use cad- mium hexacyanoferrate for the detection and gravimetric determination of the alkali metals ; in the Nuclear Energy industry G. B. Barton J. L. Heyworth E. D. McClanahan R. L. Moore and H. H. van Juyl (Ind. Engng Chem. 1958,50,212; Chem. Abstr. 1958,52,9533 and 12337) and R. L. Moore and R. E. Burns (Int. Cowf. Treat. Stor. of High Level Radioactive Wastes A/Conf. 15/p. 1768 Geneva 1958) had isolated radio-caesium from fission products by co-precipitation with nickel and zinc hexacyanoferrates and S. 2. Roginsky M. I. Janovskij V. Al'tshuler A. E. Morokhovets and E. T. Malinina (Radiokhimiya 1060,2,438; Ckeutz. Abstr. 1962 56 137421) had investigated the adsorption of caesium on a pre-formed precipitate of the nickel complex and had claimed high enrichment.When investigations began in Swansea in 1964 there was no evidence of such complexes having been applied to column chromatography or of important parameters such as saturation capacity relative rates of caesium ion adsorption and elution of adsorbed ions having been determined for them. A number of hexacyanoferrates were prepared by direct precipitation from solutions of potassium ferrocyanide and a suitable salt of the following metals copper lead zinc man- ganese cobalt cadmium and nickel. The compounds K,[CaFe(CN),] and K,[ZnFe( CN),] were obtained commercially. For batch exchange studies they were obtained as bivalent metal hexacyanoferrates dried a t 110" C; bivalent metal hexacyanoferrates dried at 20" C; and mixed potassium metal hexacyanoferrate dried at 20" C.M solutions by trituration of solid reactants or by reaction of the soluble metal salt with solid potassium ferrocyanide in ethanol - water media adsorption studies were carried out 011 a constant particle size of 200 mesh. M solutions of caesium chloride (with caesium-137 tracer) was more effective with bivalent metal hexa- cyanoferrates dried at 20" C than at 110" C. The following complexes were found to be most efficient manganese cobalt cadmium zinc and copper in that order. Caesium adsorption by potassium metal hexacyanoferrates indicated that the cadmium and cobalt complexes would be superior to the others described in performing an efficient column separation. Saturation capacity determinations for the zinc cadmium cobalt manganese and copper( 11) hexacyanoferrates were in good agreement with the theoretical values assuming Cs,[MFe(CN),] to be the limiting salt.Soon after these results were obtained the first of a series of papers was published written by V. KouEim and colleagues ( J . Inorg. NucZ. Chem. 1964 26 1111 and 1176; and CoZZn Czech. Chem. Commuw. 1965,30 2848) who had also investigated the possibility of using heavy-metal hexacyanoferrates as ion exchangers for the isolation and separation of the alkali metals. Although no measurements on relative rates of adsorption on either the bivalent metal complexes or their potassium analogues were carried out KouEim investigated satura- tion capacities and elution of adsorbed ions both batchwise and dynamically.Potassium analogues were not investigated. KouEim had also found that batch capacities agreed closely with the theoretical values although column capacities were less. Batch desorption experi- ments indicated that caesium was readily desorbed from the zinc and copper complexes with nitric acid and ammonium nitrate but little was desorbed from bismuth lead nickel cad- mium cobalt (in descending order). Koufim reported granular hexacyanoferrates which gave Because stable granular products could not be obtained even from Batch studies showed quite clearly that adsorption of caesium ion from 148 RESEARCH TOPICS IN ANALYTICAL CHEMISTRY [Proc. SOC. Analyt. Chein. the following separation factors in to 5 M nitric acid caesiurn - rubidium approximately 7 ; rubidium - potassium approximately 10.Distribution coefficient measurements for dilute alkali metal solutions in nitric acid and ammonium nitrate showed that the reaction was a. true ion cxchange conforming to the Mass Law. 147. E. Prout E. R. Russell and H. J Groh ( J . Inorg. Nucl. Chem, 1966,27 473) carried out an investigation on a granular form of potassium cobalt hexacyanoferrate and although capable of an efficient column separation of the alkali metals no satisfactory method of elution of the adsorbed caesium could be found. The saturation capacity in this case on a particle size 30 to 60 mesh was only0.25 indicating a surface process. Their attempts a t producing granular forms of the corresponding zinc manganese cadmium nickel and copper complexes failed the products being slimes that dried to fine powders.Recently tungsten and molybdenum hexacyanoferrates were applied by J. IWil (J. Inovg. Nzd. Chem. 1965,27,233) to alkali metal separations the former having an exchange capacity of 1-02 with respect to caesium. Hexacyanof errates compared f avourably with the more widely used modern ion ex- changers vix. ammonium phosphomolybdate and zirconium phosphate. Both of these exchangers possessed the advantage of being available in granular forms and allowing the adsorbed ions to be easily eluted which at present was a major disadvantage of hexacyano- ferrates. Nevertheless the saturation capacities of the latter were higher in neutral and acidic media and as they were cheap and easily prepared they might be economically better removal agents for caesium-137 etc. Separation factors for pairs of alkali metal ions were not less than those determined for zirconium phosphate but were smaller than those for ammonium phosphomolybdate.Although ammonium phosphomolybdate was highly selective for caesium in concentrated acid solutions tervalent and bivalent metals were adsorbed between pH values of 2 to 5 and at greater than pH 5 breakdown of the exchanger occurred. Hexacyanoferrates were stable over a greater pH range (caesium > rubidium > potass- ium (adsorbed)). There was still lack of evidence of their selectivity for alkali metals in the presence of interfering bivalent and tervalent metal ions. DISCUSSION DR. A. A. SMALES enquired as to the extent of radiation damage on hexacyanoferrates. Mr. Straclling referred to work reported by W. E. Prout E. R. Russell and H.J. Groh ( J . Inorg. Nucl. CJaem. 1965 27 233) on potassium cobalt hexacyanoferrate. It was found that the amount of caesium ion adsorbed from an alkaline waste solution was reduced from 95 to 72 per cent. after exposure to a dose of G x lo8 rad from a cobalt40 source. Slight decomposition at very high racli- ation doses was thercfore indicated. MR. SMITH asked if any work had been reported on the use of other complex cyanides other than liexacyanoferrates as inorganic ion exchangers. Mr. Stradling said that Langford (U.S. Atomic Energy Commission Report HW-49668 1957) had succeeded in isolating radiocaesium from large amounts of fission products by co-precipitation with cobalt cobalticyanide but that there appeared to be no systematic or detailed studies on other than ferrocyanides for performing column separations of the alkali metals.MR. BISHOP asked whether the 2 1 stoicheioinetry M;;M"Fe(CN),] had been established experimentally or assumed ; and if this structure was authentic whether the more stable 2 3 dimers M:[M'i Pe(CN),] had been examined for ion-exchange properties. Mr. Stradling said that there was direct and indirect evidence for a 2 1 stoicheiometry. The hexacyanoferrates which Mr. Strad- ling prepared were analysed for potassium transition metal and ferrocyanide ions. The results obtained were in good agreement with the theoretical values assuming the complexes to have the formulae I<,[MFe(CN),]. Slight deviations indicated that the complexes were not pure but con- tained a slight proportion of occluded potassium ferrocyanide and bivalent metal hexacyanoferrate itself.Similar results were obtained by W. E. Prout E. R. Russell and H. J. Groh ( J . Inorg. Nztcl. Clzem. 1965,27 473) who also observed that a 2 1 stoicheiometry occurred in Cs2[MI1 Fe(CN),]. Expcrimeiital values of saturation capacity determined by the speaker were in good agreement with the theoretical values assuming the limiting caesium salts to be as above. The values obtained by V. Koui-im J . Rais and B. Million ( J . Inovg. Nucl. CJicwz. 1964 26 1111) were also in good agrcenient. September 1966 J RESEARCH TOPICS IN ANALYTICAL CHEMISTRY 140 Dimers and other polymeric forms had not been studied as potential ion exchangers to Mr. S tradling’s knowledge although it was apparent that the following existed K,Zn,,[Fe(CN),] K,Zn,[Fe (CN) J3 K,Zn3 [Fe (CN) and K,Mn,[ Fe (CN) ,I3.The Use of Heterocyclic Azo Dyes and Related Compouiids in Analytical Chemistry BY R. G. ANDERSON AND G. NICKLESS (Departinent of Inorganic Chernistvy School of Chemistvy Univevsity of Bvistol) MR. ANDERSON said that heterocyclic azo dyestuffs were first used as analytical reagents in 1955 when Cheng and Bray (Analyt. Chew. 1955,27,782) proposed the use of 1-(2-pyridylazo)- 2-naphthol (PANP) as a complexometric indicator for various metals. About 3 years later PANP was also proposed by Cheng as a reagent for solvent extraction spectrophotometric determinations particularly with uranium (AnaZyt. Chew. 1955 30 1027). Wehber (2. analyt. Chenz. 1957 158 10) suggested 4-(2-pyridylazo)resorcinol (PAR) as an alternative to PANP for use with EDTA because (unlike the former) it was water soluble.As the com- plexes of PAR had such high molar extinction coefficients PAR became popular as a colori- metric reagent initially as a reagent for cobalt uranium and lead (F. H. Pollard P. Hanison and W. J. Geary AnaZytica Chzim. Acta 1959,20 26) but later for many other metals. Both reagents had since found a variety of uses in colorimetric and complexometric analysis. The chromatographic separation of metal ions had been of interest for several years. To render these visible on a developed chromatogram reagents that were highly sensitive to as many cations as possible were needed. As PAR and PANP seemed at the time to be the most outstanding reagents produced for this purpose it was decided to synthesise a whole range of new reagents with a similar chelating system (a heterocyclic nitrogen atom and hydroxyl group 0-0’ to an azo linkage) and compare their properties with the two former reagents.However although 2-aminothiazole and 2-aminobenzothiazole could easily be diazotised and coupled with a wide range of phenols diazotised 2-aminopyridine coupled only with a few phenols with difficulty and 2-aminopyrimidine could not be diazotised at all. 4-(2-thiazo- 1ylazo)resorcinol and 1-(2-thiazolylaz0)-2-naphthol proved to be quite popular as colorimetric reagents but in the speaker’s experience they were inferior to their pyridylazo analogues for the following reasons (T. J. Samuelson Ph.D. Thesis University of Bristol 1965) they were less soluble; they were less useful as spray reagents owing to stronger background colours; and they were more limited in applications in solution because of lower acid dis- sociation and chelate stability constants all ligands of this type forming strongly coloured anions in alkali that masked the colours of the chelates.Only as indicators did they show any promise of being superior. It was therefore decided to look for new methods of preparing these dyes and two methods seemed to have possible potential use. (i) The oxidative coupling method of Hunig (U.S. Patent 2,832,764 1958) involved reacting a heterocyclic hydrazone or tautomeric hydrazine with a phenol in the presence of an osidising agent with conditions under which normal azo coupling would be carried out. The dye produced was the same as would be expected by azo-coupling. Although this method was tried with 2-hydrazino derivatives of pyridine pyrimidine and benzothiazole only with 2-hydrazinobenzothiazole were substantial amounts of dye obtained and these could be obtained without difficulty by the normal routes.However an impure sample of 1-(2-pyrimi- dylazo)-2-naphthol was obtained and could be used as a spray reagent and indicator. (ii) The second method involved reacting the same hydrazines with o-quinones in the presence of acid (Th. Zincke and H. Bindewald Ber. 1884 3026). This method worked well in all cases and generally the dyes produced were not the same as those derived from azo coupling reactions. Thus o-benzoquinone gave 0-azo derivatives of phenol and P-naphtho- quinones invariably gave 2-azo-a-naphthols. This method was used to prepare most of the azo dyes studied.The dyes were initially studied as chromatographic spray reagents and as indicators. Then the spectra of the dyes at various values of pH and also of the complexes were measured. Finally the acid dissociation constants of the dyes and the stability constants of the complexes 150 RESEARCH TOPICS IN ANALYTICAL CHEMISTRY [PYOC. SOC. Aqzalyt. ChCllZ. were determined with either spectrophotometric or potentiometric methods. A computer programme was written to obtain the best pK values from the experimental results. 2-(2-Pyridylazo)phenol was a pale yellow dye that formed a bright orange anion in alkali solution (pKoH = 9.42) and a yellow cation in acid solution (pKNH = 1.85). The molar extinction coefficients of it and its complexes were only about half those of PAR but the bathochromic shifts on chelation were much greater which was an advantage.It formed complexes with the same metals as PAR and the chelate stability constants were high although not quite as high as those of PAR. 2-(2-Pyridylazo)-l-naphthol (PANcc) an isomer of PANP was different from the latter in several respects. Like all the naphthol dyes studied it showed a hypsochromic shift on protonation and a bathochromic shift on ionisation. However the dye its cation anion and complexes all absorbed light at longer wavelengths than the corresponding ones of PANP. Its PKOH value was 2 units lower (10.00 instead of 12.00) and log K of the copper complex was 14.6 instead of 17.0. In order to make PANE water soluble 5 new dyes were prepared with sulphonic acid groups in positions 4 to 8 of the naphthalene ring respectively.The spectra of these com- pounds and their chelates resembled those of PANa but the pKoH values were lower. Also a uniform variation relating bathochromic shift to pK was noticed both for ionisation and for chelation. These shifts were lowest for 2-(2-pyridylazo)-l-naphthol-4-sulphonic acid greater for the 5 6 7 and non-sulphonated dyes and greatest for the 8-sulphonated dye in which the sulphonic acid group was close enough to play a part in chelation. This meant that as a colorimetric reagent 8-sulphonated PANcc was superior both with regard to colour change and stability of complexes whereas 4-sulphonated PANE was the least useful although as a spray reagent it produced the best defined colours. The pyrimidylazo analogues of these 7 dyes were prepared by a similar method and a comparison of properties between them and the pyridylazo dyes was made.They were more water soluble and as spray reagents produced better defined colours with all metals but particularly with those more electropositive metals that the pyridylazo dyes were less sensitive towards (such as metals in groups IIA and IIIA of the periodic table). The batho- chromic shifts observed on ionisation and chelation were always larger with the pyrimidylazo dyes a useful advantage. Pyrimidine however was a weaker base than pyridine and the pKNH values of the dyes were found to be 1.5 to 2 units lower. Similarly the pKoH values were found to be 0.3 to 0.6 units lower. This meant that one would expect the metal complexes to be less stable and this was in fact found to be so to the extent of 0.5 to 2 pK units.Obviously this was a slight disadvantage for their use in colorimetric analysis although in complexometric titrations the greater gap in stability between the metal EDTA and metal - indicator complexes tended to give rise to sharper end-points. A good example of this was in the titration of copper at pH 4 to 6 which was good with a pyrimidylazo dye as indicator but with a pyridylazo dye the colour change at the end-point was slow. The remarks concern- ing the sulphonated pyridylazo dyes applied almost equally to the sulphonated pyrimidylazo dyes. 2-(2-Pyrimidylazo)-l-iiaphthol-4-sulphonic acid was observed to be the most effective chromatographic spray reagent of all the dyes studied. The benzothiazolylazo analogues were also prepared but were found to be less useful for the reasons mentioned earlier in connection with the thiazolylazo dyes.As indicators for copper they were very successful giving sharp end-points Several other groups of dyes in which the basic PAN type chelating structure (hetero- cyclic nitrogen and hydroxyl group 0-0’ to an azo linkage) had been altered were also prepared. Thus P-hydroxyazo analogues of these dyes were prepared by coupling the hydrazines with $-benzoquinone and a-naphthoquinone. These produced strong colours with a few metals in groups VIII and IB of the periodic table only. Also the pH range in which they were produced was narrow. The ligands themselves ionised at lower values of pH because of the lack of intramolecular hydrogen bonding. Potentiometric titrations showed the loss of one proton per ligand molecule on production of the intense chelate colour the log stability constants of the complexes being about a half to a third of those of the o-analogues.Removal of the o-hydroxyl group in PAR therefore introduced a certain amount of selectivity into the molecule. 8-Hydrazinoquinoline was condensed with a-naphthoquinone P-naphthoquinone and ~-naphthoquinone-4-sulphonic acid to produce ligands capable of forming &membered chelate rings. The dyes so produced were much more red and the complexes differed only slightly September 19661 RESEARCH TOPICS IN ANALYTICAL CHEMISTRY 151 in colour. 4-(8-Quinolylazo)-l-naphthol showed the same selectivity as 4-(2-pyridylazo)- 1-naphthol. 2-(8-Quinolylazo)-l-naphthol-4-sulphonic acid seemed to be the most sensitive and had a pink fluorescence that was either quenched or replaced by a blue fluorescence on chelation with most metals.It showed a hypsochromic shift on protonation and ionisation and small bathochromic shifts on chelation. Good colour changes were produced with cobalt and iron. Potentiometric titrations showed it to act as a powerful terdentate ligand both pKoH and stability constants being higher than those of the 8-pyridylazo analogue. The hydrazines were condensed with salicylaldehyde to produce yellow or white hydra- zones that gave bathochromic shifts on protonation ionisation and chelation although the colour changes were poor. All acted as terdentate ligands and gave stability constants higher than those of 2-(pyridylazo)phenol with the exception of salicylaldehyde-8-quinolyl hydra- zone which were lower.This latter compound formed two 6-membered rings as opposed to a &membered and 6-membered ring on chelation with metals. 8-Aminothiophenol was condensed with pyridine-2-aldehyde to give the thio analogue of 2-pyridylidene-o-aminophenol. The former produced a larger bathochromic shift on chelation and showed a marked selectivity to transition metals from group VIIA to IIB and to indium thallium lead and bismuth i.e. those metals that formed brightly coloured insoluble sulphides. Mr. Anderson concluded by saying that they had found that of the compounds studied only those that contained the basic PAN-type chelating structure gave the sensitive and general colour reactions associated with PANP. DISCUSSION MR. J. D. R. THOMAS asked whether the behaviour of the heterocyclic azo dyestuffs as indicators in complexometric titrations offered any advantages over the conventional indicators.Mr. Anderson replied that all of the dyes studied had lower chelate stability constants than those of 1-(2-pyridylazo) -2-naphthol. This implied a greater difference in stability between the metal - EDTA and metal - indicator complexes. This in turn caused . the reactions were often faster. pyridine-%aldehyde had been prepared- MR. I<. SMITH mentioned that the thio-substituted Schiff the end-points to be sharper base from o-aminothiophenol and and He referred to work by Freiser ( J . AWCY. Chem. SOC. 1964 86 3056) who reported that similar compounds underwent re-arrangement during preparation to thiazolines. The corresponding thiazoline from the previously mentioned compound would be- Had Mr.Anderson found this re-arrangement occurring in this example or was the Schiff base obtained as the initial product? Mr. Andcrson said that spectroscopic (infrared and ultraviolet) and potentionietric evidence suggested that the compound existed as a thiazoline when not in the presence of metals. However with metals i t acted as a strong terdentate ligand losing one proton per molecule on chelation and behaving as a Schiff base. Although the chelates were stable in air the ligand quickly lost two atoms of hydrogen to form 2-(2-pyridyl)benzothiazole at the same time losing its ability to form strong colours with metals. DR. BETTERIDGE referred to Mr. Thomas’ comments about “conventional indicators,” and considered 1- (2-pyridylazo) -2-naphthol as a conventional indicator.He asked whether the new variations could be used a t as low a pH as 1-(2-pyridylazo)-2-naphthol could be used; and whether they and especially the thio-derivative had the same stability towards decomposition as 1-(2- pyridylazo) -2-naphthol. Mr. Anderson replied that the new variations of 1-( 2-pyridylazo) -2-naph- tho1 all formed Complexes with metals a t pH values as low as if not lower than those a t which the 152 PUBLICATIONS RE CBIVED [Proc. SOC. Analyt. Clzcnz. latter formed complexes. The explanation of this was that although the chelate stability constants were lower this was more than offset by lower pKa values of the dyes. The pyridylazo dyes were stable but the pyrimidyl azo dyes decomposed slowly in solution. This appeared to be catalysed by acid but he did not think it was serious enough to be a handicap to their use.The thio derivative was oxidised by sir quite rapidly and this was a major dis- advantage in its use. MR. EARK asked whether the two compounds hacl been used in the complcxometric detcrmina- tion of low concentrations of metals as there was a sharp bathochromic shift between the spectra of the indicator and the metal complex. The colour change would probably permit an easy photo- metric determination of the end-point to be made. Mr. Anderson said that the dyes had been used successfully with solutions of metals down to low3 M. Below this the end-points tended not to be sharp and the dyes were then more useful as spectrophotoinetric reagents. Changes in the Register of Members DEATHS WE record with regret the deaths of Alfred Louis Bacharach Frederick Harry Howell Eric Stanley Thomas Arthur Israel Vogel Winifred Edris Welton.

ISSN:0037-9697    

DOI:10.1039/SA9660300140

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

152 PUBLICATIONS RE CBIVED [Proc. SOC. Analyt. Clzcnz. Publications Received The publications listed below have been received by the Editor of The Analyst in which journal Book Reviews will continue to appear. APPLIED INFRARED SPECTROSCOPY. Edited by DAVID N. KENDALL Ph.D. Pp. xvi + 560. New York Reinhold Publishing Corporation. London Chapman & Hall Ltd. 1966. Price $23.00. MANUAL ON RECOMMENDED PRACTICES IN SPECTROPHOTONETRY. Sponsored by A.S.T.M. Com- mittee E-13 on Absorption Spectroscopy. Pp. viii + 113. The American Society for Testing and Materials. Price $3.50; to members of the American Society for Testing and Materials $2.45. Pp. x -t 270 196G. FUNDAMENTAL PRINCIPLES OF CHEMICAL ANALYSIS. By WILLIAM F. PICICERING. Amsterdam London and New York Elsevier Publishing Company.Pp. svi + 444. 105s. 1966. Price 60s. DIFFUSIONAL SEPARATION PROCESSES THEORY DESIGN AND EVALUATION. By EARL D. OLIVER. 1966. Price New York London and Sydney John Wiley & Sons Inc. THE IDENTIFICATION OF ORGANIC COMPOUNDS. A MANUAL OF QUALITATIVE AND QUANTITATIVE METHODS. Sixth Edition. By STIG VEIBBL Dr.Phi1. Pp. xvi + 452. Copenhagen G.E.C. Gad Publisher. 196G. INFRARED BAND HANDBOOK SUPPLEMENTS 3 AND 4. Edited by HERMAN A. SZYMANSKI. Pp. svi + 261. New York Plenum Press Data Division. 1966. Price $15.00. PROGRESS IN THE CHEMISTRY OF FATS AND OTHEK LIPIDS. Volume 8. Part 3 (Chromatography). By DONALD C. MALINS. Column Chromatography of Pp. iv + Oxford London Edinburgh New York Paris and Frankfurt Pergamon Press Recent Developments in the Thin-Layer Chromatography of Lipids.Paper Chromatography of Lipids. Lipids. 301-420. 1866. Pricc 40s.; $6.50. By JAMES G. HAMILTON. By ROBERT A. STEIN and VIDA SLAWSON. Edited by R. T. HOLMAN. September 19661 PUBLICATIONS RECEIVED 153 ANALYTICAL APPLICATIONS OF ION EXCHANGERS. By J. INCZEDY. Pp. xii -t 443. Osford 1966. Price 105s. CLINICAL PHARMACY A TEST FOR DISPENSING PHARMACY. By GLENN L. JENKINS GLEN 3. Pp. viii + 379. New York Toronto Sydney and London Edinburgh New York Paris and Frankiurt Pergamon Press. SPERANDIO and CLIFTON J. LATIOLAIS. London McGraw-Hill Book Company. 1966. Price 96s. Chicago Toronto and London Holt Rinehart and Winston Inc. EQUILIBRIA IN SOLUTION. By GEORGE M. FLECK. Pp. xviii f 217. New York Sail Francisco A CONTRIBUTION TO THE ANALYTICAL CHEMISTRY OF SILICATE ROCKS A SCHEME OF ANALYSIS 1966.Price $7.95. FOR ELEVEN MAIN CONSTITUENTS BASED ON DECOMPOSITION BY HYDROFLUORIC ACID. By F. J. LANGMYHR and P. R. GRAFF. Pp. 128. Oslo Universitetsforlaget. 1965. Noyges Geologiske Undersoldse Numbev 230. HANDBUCH DER KOLORIMETRIE. BAND I11 KOLORIMETRIE IN DER BIOLOGIE BIOCHEMIE UND MEDIZIN. By DR. BOHUMIL KAKAC and ZENEK J. VEJDELEIC. Pp. xiv + 857. Jena Veb Gustav Fischer Verlag. 1966. Price 129s. 6d. BRITISH MEDICAL BULLETIN. Volume 22 No. 2. May 1966. Edited by R. A. KEKWICI<. Pp. i & xiv + 103-194. London Medical Department. The British Council. 1966. Price 30s. AN INTRODUCTION TO ELECTRON PARAMAGNETIC RESONANCE. By MALCOLM BERSOHN and 1966. JAMES C. BAIRD. Price $15.00. BIOORGANIC MECHANISMS. Volume 1. By THOMAS C. BRUICE and STEPHEN J. BENKOVIC. Pp.viii + 362. New York and Amsterdam W. A. Benjamin Inc. 1966. Price $22.50. BASIC CHEMICAL THERMODYNAMICS. By JURG WASER. Pp. xviii + 278. New Yorli and Amsterdam W. A. Benjamin Inc. THE INVESTIGATION OF ORGANIC REACTIONS. By Ross STEWART. Pp. xvi + 125. London Sydney Toronto Delhi Tokyo. Prentice-Hall Inc. 1966. Price (cloth) 44s ; (paper) 20s. GAS CHROMATOGRAPHY ABSTRACTS 1965. Edited by C. E. H. KNAPMAN; Assistant Editors D. R. BROWNING and S. G. PERRY. Pp. x + 304. Sponsored by The Gas Chromatography Discussion Group of the Institute of Petroleum. 1965. Price 03s. Characteristic GI-OUPS containing Carbon Hydrogen] Oxygen Nitrogen Halogen Sulfur Selenium and/or Tellurium. Pp. xviii + 260. London Butterworths (Publishers) Ltd. 1965. Price 47s. 6d. USE OF NEUTRON GENERATORS IN ACTIVATION ANALYSIS.By J. E. STRAIN. Progress in Nuclear Energy Series IX Analytical Chemistry Volume 4 Part 3. Pp. iv + 137-157. Oxford London Edinburgh New York Paris Frankfurt. Pergamon Press. 1965. Price 10s. INSTRUMENT AND CHEMICAL ANALYSIS ASPECTS OF ELECTRON MICROANALYSIS AND MACROANALYSIS. By HERBERT E. ELION. Progress in Nuclear Energy Series IX Analytical Chemistry Volume 5. Pp. x + 256. Oxford London Edinburgh New York Paris Frankfurt. Per- gamon Press. 1966. Price 90s. POLYSACCHARIDES PEPTIDES AND PROTEINS. By R. T. COUTTS and G. A. SMAIL. Pp. x + 209. London William Heinemann Medical Books Ltd. 1966. Price 30s. THE ANALYTICAL CHEMISTRY OF COBALT. By RONALD S. YOUNG. Pp. viii + 170. Oxford London Edinburgh New York Toronto Paris Braunschweig Pergamon Press. 1966. Price 45s. DEVELOPMENT OF A METHOD FOR THE RAPID DETERMINATION OF THE NITROGEN CONTENT OF STEEL BASED ON THE VACUUM FUSION METHOD WITH SPECIAL CONSIDERATION OF THE MELTS. By AXEL GERHARDT THADDAUS KRAUS and MARTIN G. FROHBERG. Pp. 106. Balzer Balzers Aktiengesellschaft. 1965. Pp. xii + 274. New York and Amsterdam W. A. Benjamin Inc. 1966. Price (cloth) $6.00; (paper) $4.35. London The Institute of Petroleum. NOMENCLATURE OF ORGANICHEMISTRY. Definitive Rules for Section C. Volume 4. METALLURGICAL PROCESSES INVOLVED I N THE DE-GASSING O F CARBON-SATURATED IRON

ISSN:0037-9697    

DOI:10.1039/SA9660300152

出版商:RSC    

年代:1966

数据来源: RSC

摘要:

154 NOTICES [PYOC. SOC. A.nalyt. Chenz. No tic e s SYMPOSIUM ON THE CHEMICAL LITERATURE A TWO-DAY symposium on The Chemical Literature will be held at the Borough Polytechnic on Wednesday November 30th and Thursday December lst 1966. Further details may be obtained from the Secretary Borough Polytechnic Borough Road London S.E.l. BRITISH STANDARD INSTITUTION A FEW copies of the following draft specifications issued for comment only are available to members of the Society and can be obtained from the Secretary The Society for Analytical Chemistry 14 Belgrave Square London S.W.l. DRAFT SPECIFICATIONS Draft Specifications prepared by Technical Committee TPC/3-Pyridine. 66/13119-Draft B.S. Specification for Pyridine (Revision of B.S. 3096-97). 66/13732-Draft B.S. Specification for Pyridine Bases (Revision of B.S.3098-99). Draft Specification prepared by Technical Committee ISE/l8-Sampling and Analysis of Iron and Steel. Part 51 Phos- phorus in Ferro-chromium Ferro-manganese and Ferro-molybdenum Photo- metric. Draft Specifications prepared by Technical Committee CIC/21-Ammonia and Nitric Acid. 66/14805-Draft B.S. Methods of Test for Liquefied and Anhydrous Ammonia. 66/14806-Draft B.S. Methods of Test for Ammonium Nitrate. Draft Specification prepared by Sub-committee RPE/1/1-Chemical Analysis of Refractories on behalf of Technical Committee RPE/1-Methods of Testing Refractory Materials. 66/14937-Draft B.S. Methods of Testing Refractory Materials (B.S. 1902). Addendum to Part 2C The Chemical Analysis of Chrome-bearing Materials (See 66/8339). Draft Specification prepared by Sub-committee LBC/1 l/l-Microchemical Apparatus (Drafting).66/15822-Draft B.S. Specification for Micrometer-operated Burette (Revision of B.S. 1428 Part D6). Draft Specification prepared by Technical Committee LBC/S-Glassware for Pharma- ceutical Purposes. 66/15823-Draft B.S. Specification for Dispensing Measures for Pharmaceutical Purposes (Metric Units) (Revision of B.S. 1922). Draft Specification prepared by Technical Committee LBC/'I-Laboratory Porcelain and LBC/9-Silica Laboratory Ware. 66/14637-Draft B.S. Methods for the Analysis of Iron and Steel. 66/15853-Draft B.S. Specification for Porcelain and Silica Crucibles. ROYAL INSTITUTE OF CHEMISTRY AWARD OF THE MELDOLA MEDAL FOR 1965 THE Meldola Medal for 1965 has been awarded to Robert David Gillard for his work in the field of inorganic chemistry with special reference to the chemistry of transition-metal com- plexes and their optical activity.The Meldola Medal which is the gift of the Society of Maccabaeans is normally awarded annually the award for a particular year being made to the chemist who being a British subject and under 30 years of age on December 31st in that year shows the most promise as indicated by his or her published work. Awards are made by the Council of the Royal Institute of Chemistry with the concurrence of the Society of Maccabaeans on the recom- mendation of a specially appointed advisory committee. NOTICES After spending 2 years in the Royal Air Force Robert Gillard entered St. Edmund Hall Oxford in 1956 and graduated in 1960 having begun research under the direction of Dr.(now Professor) H. M. N. H. Irving. Dr. Gillard was appointed Assistant Lecturer at Imperial College in 1961 and Lecturer in 1963. He is the author of the review paper “Circular Dichroism,” published in The Analyst in November 1963. He moved to a Lectureship at the University of Sheffield in 1964 and in October 1966 will be taking up a new appointment as Reader in Inorganic Chemistry in the University of Kent at Canterbury. THE 1 8 ~ ~ PITTSBURGH CONFERENCE THE 18th Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy Inc. will be held at the Penn-Sheraton Hotel in Pittsburgh Pennsylvania U.S.A. from March 6th to loth 1967. Approximately 250 papers on all aspects of analytical chemistry and spectroscopy will be presented. Symposia proposed for this Conference are- 1.2. 3. 4. 5 . 6. 7. 8. 9. 10. Laser Excitation Raman Spectroscopy. Information Retrieval and Data Handling. Bio-medical Applications of Gas Chromatography. Coblenz Symposium on Infrared Spectroscopy. Analytical Chemistry in Air and Water Pollution. Computer Applications in Analytical Chemistry. X-Ray Analysis of Light Elements. Analytical Techniques in Non-aqueous Systems Carbon-13 N .M. R. Spectroscopy. Emission Spectroscopy in the Vacuum Ultraviolet. Original papers on all phases of analytical chemistry and spectroscopy are invited. A brief abstract (150 words) of each paper will be printed in the programme. Three copies of this abstract with a letter giving the names of the authors the laboratory in which the work was carried out and the current addresses of the authors should be addressed to Dr. Gerald L. Carlson Programme Chairman The 18th Pittsburgh Conference Inc. Mellon Institute 4400 Fifth Avenue Pittsburgh Pennsylvania 15213 U.S.A. The final date for receipt of abstracts is October 15th 1966. In addition to the programme of technical papers there will be an exhibition of the More than 200 companies will display instruments newest analytical instrumentation. chemicals and equipment.

ISSN:0037-9697    

DOI:10.1039/SA9660300154

出版商:RSC    

年代:1966

数据来源: RSC