摘要:

Proceedinas - wof the Analytical Division ofThe Chemical SocietyCONTENTS131 Research and Development Topicsin Analytical Chemistry131 New Members of Council135 Summaries of Papers135 'Gel Permeation Chromatography'138 'On-line Techniques for Process143 'Sources for Emission Spectroscopy'151 Equipment News156 Fourth SAC Conference157 New BS Specifications forThermometers157 New APA President158 Conferences and Meetings158 Courses159 Publications ReceivedMonitoring'Volume 14 No 6 Pages 131 -1 60 June 197PADS DZISSN 0306-1 3961 4( 6) 1 31 -1 60 (1 977) June 1977PROCEEDINGSOF THEANALYTICAL DIVISION OF THE CHEMICAL SOCIETYOfficers of the Analytical Divisionof The Chemical SocietyPresidentD. W. WilsonHorn SecretaryP. G.W. CobbSecretaryMiss P. E. HutchinsonHon. Treasurer Hon. Assistant SecretariesJ. K. Foreman D. 1. Coomber, O.B.E.; D. C. M. Squirrel1Editor, ProceedingsP. C. WestonProceedings is published by The Chemical Society.Editorial: The Director of Publications, The Chemical Society, Burlington House, London, W1 V OBN.Telephone 01 -734 9864. Telex 268001.Subscriptions (non-members) : The Chemical Society, Distribution Centre. Blackhorse Road,Letchworth, Herts., SG6 1 HN.Non-members can only be supplied with Proceedings as part of a combined subscription with The Analystand Analytical Abstracts.Q The Chemical Society 1977The Analytical DivisionFourth SAC ConferenceUniversity of Birminghamwill be held at theonJuly 17-22, 1977This Conference is organised by the Analytical Division of The Chemical Societyand sponsored by IUPAC.The scientific programme, published in full in the May issue of Proceedings(p. 11 8), will cover all aspects of analytical chemistry; there will be an extensiveexhibition of manufacturers' equipment and an attractive selection of social eventsfor delegates and their guests.Details of the Conference and registration forms can be obtained by applicationto the Secretary of the Analytical Division, The Chemical Society, BurlingtonHouse, Piccadilly, London, W1 V OBN

ISSN:0306-1396    

DOI:10.1039/AD97714FX019

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

Vol. 14 No. 6 June 1977 New Members of Council Vice-president Jack Whitehead, a new Vice-president of the AD, was educated at the High School, Middles- brough, and in 1948 obtained a London Uni- versity BSc degree in chemistry as a part-time student at Constantine College. Most of his practical chemistry was learned at ICI, Billing- ham Division, where his first job a t the tender age of 16 was to prepare all the standard solutions used in the Control Laboratories-a task he per- formed lightly at the time, but he now shudders at the responsibility he carried.After 10 years with ICI he moved to his present company, Tioxide International Ltd., and he has held his present position for 20 years. MY. J. Whitehead During this time the analytical activities of the form a subsidiary, Technical & Analytical Ser- Company have expanded rapidly and he now vices Ltd., for marketing these services and he controls a large and vigorous group in which has been agreeably surprised at the success of most of the techniques used in analysis are this venture, which is now occupying a sub- represented. He persuaded his Company to stantial portion of his time.He has a keen 131132 NEW MEMBERS OF COUNCIL Proc.Analyt. Div. Chem. SOC. interest in laboratory safety and is Chairman of the Health & Safety Committee of his Company’s Central Laboratories. Mr. Whitehead joined the SAC in 1950 and in 1966 became the first Honorary Secretary of the newly formed North East Region, a position he held until 1972; he served as Chairman in 1973- 75.Since 1972 he has been a Member of Council of the AD and in addition is a member of the Programmes Committee and represents the AD on the Industrial Division Council. He is a Fellow of the Royal Institute of Chemistry and has been a member of his Local Section Committee on a number of occasions. Away from work his main interests are classical music, bridge, football (as a spectator), keeping his garden tidy, and trying to play to his golf handicap.He is married with two daughters. Professor R. Belcher. A biography and por- trait of Professor Belcher appeared in Proceed- ings, 1974, 11, 193. Dr. H. Hughes is the new Chairman of the North East Region. He graduated from the University College of North Wales, Bangor, in 1949, obtaining a First-class Honours degree in physics.He then worked on X-ray diffraction under Professor E. A. Owen and obtained a PhD, after which he joined United Steel Companies Ltd. in Sheffield; he has since remained in the steel industry. The period 1949-66 was devoted to the application of X-ray diffraction in the examination of structural and precipitation phenomena in alloy steels and he is the author and co-author of many papers on the subject.In 1966 he became interested in X-ray fluorescence analysis and was made responsible for the development of this together with other, spectrometric techniques, again publishing papers on the subject. During the whole of this period he was located at Swinden Laboratories, Rotherham, firstly with United Steels and then with British Steel Corporation, Special Steels Division.In 1970 he transferred to the new General Steels Divisional Research Centre being built on Teesside, being responsible for the Chemical Services Department and the development of instrumental and chemical methods for pro- duction control, metallurgical processes and monitoring environmental pollution. He is now Chairman of the BSC/BISPA Chemists’ Committee, which co-ordinates analytical de- velopments in the steel industry.He is married, with one son who has not been put off studying chemistry at Newcastle University. At Sheffield Dr. Hughes played what he considered to be a high standard of bridge but now concentrates on growing dahlias in so far as the North East climate will allow. John Ogleby is the new Chairman of the North West Region.He was born at Hartlepool and educated at the Henry Smith Grammar School. He gained a scholarship to Durham University, which helped to keep him out of HM Forces, and graduated in chemistry in 1949. Incidentally, a contemporary on this course was Mr. F. E. Harper, the immediate past Chairman of the North East Region. After chasing a few free radicals with radioactive tracers in the Research Department at Durham he joined AWRE, Aldermaston, in the Analytical Chemistry Section of the Materials Division.He left in 1959 to join the Analytical Research Section of Laporte Chemicals Ltd., under Mr. C. Whalley, and in 1969 moved to Widnes where Laporte centralised the research laboratories of the General Chemicals Division. He is now a Senior Principal Chemist responsible for the development of analytical methods for a variety of products and processes, using mainly physico- chemical methods.His external activities include being Chairman of the BSI Fluoride Committee and of a fluoride industry committee responsible for analytical methods for environ- mental fluoride measurements. He is happily married with a 12 year old daughter, likes a game of tennis or badminton and dabbles in photography when he can escape from the pressure of domestic duties.Dr. H . Hughes MY. J . W. Ogleby Dr. J. M. Ottaway. A biography and portrait of Dr. Ottaway appeared in Proceedings, 1975, 12, 39, on the award of the second SAC Silver Medal. Since then he has been elected as an Ordinary Member of the CS Council (1975) andJune, 1977 NEW MEMBERS OF COUNCIL 133 in 1976 he was elected to a Fellowship of the RIC.He is now a Reader in the Department of Pure and Applied Chemistry at the University of Strathclyde. Dr. J. E. Page has been a member of the research staff of Glaxo Laboratories since 1939. He has PhD (1938) and DSc (1957) degrees of London University and is author or co-author of about 100 papers, largely on applications of physical methods to organic and biochemical problems.He was a Member of Council of the SPA/SAC in 1948, 1949, 1956 and 1957 and has served as Honorary Secretary (1946-50) and Chairman (1955-57) of the Physical Methods Group (now the Special Techniques Group) and as a member of the Analytical Methods, The Analyst and Analytical Abstracts Committees. Dr.Page has also been active with other scientific societies and he has served inter alia on the Editorial Boards of Chemistry and Industry, the Journal of Applied Chemistry and Bio- technology, the Journal of the Science of Food and Agriculture and the Journal of Electroanalytical Chemistry. His other interests include archaeo- logy, foreign travel and exploring the UK.Dr. J . E . Page MY. G. E. Penketh Mr. G. E. Penketh has spent the whole of his career with ICI, joining the Billingham Division in 1945 and training as an analyst under the late H. N. Wilson. He obtained an external London University BSc degree in chemistry in 1951 and became an ARIC in the same year. Although he spent 2 years on “pure” research (working on polyphosphate compounds) and a further period on a process investigation Section, his main interests remained in analysis and he was appointed a Section Leader of the Analytical Research Section in 1961, Section Manager in 1963, and Division Analytical Manager in 1966.He became a Group Manager in 1971, when his analytical responsibilities were combined with those for technical service, physical chemistry and mathematics.At the end of 1975 he was appointed to his current position of R and D Services Group Manager with what by now had become the Petrochemicals Division. In es- sence this meant. that to his previousresponsi- bilities were added the Administration, Intelli- gence and Library, and Engineering Sections of the R and D Department. In such a job dele- gation plays an important role, but he still has only moderate success in keeping out of the way of his analysts.Mr. Penketh is a member of The Analyst Publications Committee. He is married with three children and his hobbies include gardening, painting and collect- ing coins and miniature medals. He is inter- ested in most sports and plays both tennis and badminton regularly and to a steadily decreas- ing standard.He is a regular supporter of Middlesbrough Football Club and is comforted by the thought that on statistical grounds at least after over 100 years of trying they must win something some day. Mr. R. Sawyer. A biography of Mr. Sawyer appeared in Proceedings, 1973, 10, 159. He has maintained an interest in the affairs of the Analytical Division, recently serving on the Programmes Committee (since 1973) and as Chairman of the Microchemical Methods Group (1975-77).He is at present the Vice-chairman of that Group and a Member of the Committee of the South East Region. He has been a mem- ber of The Analyst Publications Committee since 1973. As Superintendent of the Food and Nutrition Division at the Laboratory of the Government Chemist, Mr.Sawyer is concerned with a wide range of activities relating to the specification and analysis of foods. He has been a member of the Food Additives and Contaminants Com- mittee since 1973. Frank Shenton is the North East Regional Analyst and is in charge of the Regional Laboratory a t Durham, which provides analytical and scientific resources to the three Counties of Tyne and Wear, Cleveland and Durham.He is a past Vice-president of the AD. A native of Cheshire, his formal education began at the County School, Hyde, developed in many strange ways during 5 years in the war- time RAF and was completed with 3 years at the Royal Technical College of Salford, now Salford University. He was elected an Associate of the College and of the RIC in 1950. He claims that the one useful thing that he learned in the RAF134 NEW MEMBERS OF COUNCIL Proc.Analyt. Div. Chem. SOC. MY. R. Sawyer Mr. F. C . Shenton was how to solder correctly. This knowledge has been of great value in shaking the gremlins out of analytical instruments. Mr. Shenton joined the staff of the Manchester City Public Analyst in 1950 and gained his FRIC (the old Branch E Diploma) in 1953.In 1955 he moved to Durham County as Deputy Analyst and in 1965 he was appointed County Analyst, When local government reorganisa- tion took place in April 1974, the three North Eastern County Councils jointly assumed responsibility for the enlarged Regional Labora- tory and thus provided at least one example of the kind of efficient co-operation which re- organisation was designed to promote.He was a founder member of the North East Section of the SAC in 1966 and became its second Chairman in 1967. He served on the the SAC Council in 1967-68 and he is also a past member of the Council of the Association of Public Analysts. He was Secretary of the Durham Committee which was responsible for the local arrangements of the highly successful Third SAC Conference in 1971.Allan M. Ure is the new Chairman of the Scottish Region. He obtained his first degree, BSc, a t St. Andrews in 1945, awarded (in absentia and in error to George Ure) while serving as a radar officer in the RNVR. The mistake was rectified in time to allow him to complete his Honours degree in chemistry in 1948-a harrowing metamorphosis from naval Lieutenant to Honours chemistry graduate in 1 year.After joining the Department of Spectrochemistry at the Macaulay Institute for Soil Research in Aberdeen, where he has remained ever since, he gained his PhD a t Aberdeen University with a thesis “The Application of Electronics to Spectrochemistry.” He has since then been continuously involved in the development of instrumentation for analysis by emission spectrography and direct- reading emission spectrometry.He was res- ponsible for the introduction of simultaneous multi-element flame photometry for routine analysis as early as 1954 and has seen flame methods of analysis develop from the Lunde- giirdh technique to modern atomic-absorption methods. He has been active in atomic absorption since about 1960 and is still contri- buting original papers in this field. His current interests are in the development of practical spectrochemical methods for the determination of trace elements in materials of agricultural interest. More recently the evolution of techniques of spark-source mass spectrometry for comprehensive quantitative inorganic analysis has been his chief pre- occupation. For many years he has been a member of two committees devoted to the development of spectrochemical methods of analysis. Apart from a lifelong dedication to pipe smoking he quotes his principal extramural activities as gardening and hare-calling. Dr. A . M . Ure

ISSN:0306-1396    

DOI:10.1039/AD977140131b

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

June, 1977 GEL PERMEATION CHROMATOGRAPHY 135 Gel Permeation Chromatography The following is a summary of one of the papers presented at a Meeting of the Midlands Region held on January 18th, 1977, at the University of Birmingham. Analytical Gel Permeation Chromatography Using Bead Polymerised Poly(Acryloylprolylmorpholine) A. W. J. Brough, R. Epton, J. V. McLaren and G. Marr Department of Physical Sciences, The Polytechnic, Wolverhampton, W V 1 1 L Y Column packings that are used for the gel permeation chromatography (GPC) of small molecules and that are applicable in both aqueous and organic solvents are termed “univer- sal” GPC supports.Two types are available commercially: the hydroxypropyl ether of cross- linked dextran, Sephadex LH20,l and a cross-linked poly (acryloylmorpholine) , Enzacryl Gel K0.2 Both packings have their own unique gelation and swelling properties.For a column packing to be effective in the GPC of small molecules, it is essential that it undergoes gelation (xerogel formation) in the solvents used for chromatography. Multi- solvent compatibility is achieved by the inclusion of both hydrophilic and lipophilic moieties in the molecular structure of the packing network.In the case of Enzacryl Gel KO, the hydrophilic groups are essentially the exposed ether linkages of the morpholine rings, which are pendant on a polyacrylate-type backbone. In an effort to extend the available range of universal GPC supports we have prepared a new material, bead polymerised poly(acryloylprolylmorpho1ine) (PAPM) .This packing (Fig. 1) owes its water compatibility to morpholine groups, as with Enzacryl Gel KO. The proline residue was incorporated in each repeating unit in order to increase the lipophilic character, which should lead to increased organic solvent compatibility. It was hoped that this would provide for more efficient organic xerogel formation, which would be reflected in superior column efficiency. I I CH2 I CH, CH-CO-N CH-CO-NH- I ‘ 3 I CH, I I CH2 I I C H-C 0-N H-CH2-N H-CO-CH CH, CH, I L i L O - C O - f H I CH-CO-N I ‘ 3 I CH-C 0-NH-C I CH, CH-CO-N I ‘ 3 CH2 CH-CO-N co CH2 ‘ 3 I I I CH2 H2-NH-C 0-CH CH-C 0-N ‘ 3 I Fig, 1.Schematic representation of the structure of crosslinked poly(acryloylprolylmorpho1ine).136 GEL PERMEATION CHROMATOGRAPHY Proc.Analyt. Dip. Chem. SOC. Procedures for GPC Prior to column packing, the poly (acryloylprolylmorpholine) beads were graded by aqueous elutriation to give a size range of 2040 pm diameter. Following equilibration with the desired chromatographic solvent, the beads were slurried into Jobling jacketed glass GPC columns (100 x 0.4 cm i.d.), each fitted with a temporary extension (50 x 0.4 cm) and loading funnel.The latter was replaced with an end fitting and the column conditioned by pumping eluent through the system at twice the projected flow-rate (5-10 cm3 h-l; <300 p.s.i.) by means of a Milton Roy Mini-pump. Pumping was continued until no further reduction in the gel bed volume was observed (about 24 h). The temporary extension was then removed and a purpose- designed Jobling septum injection head fitted.For high-resolution GPC, two columns were coupled in series, using polytetrafluoroethylene (PTFE) tubing (0.58 mm id.). Samples to be analysed were injected under constant-flow conditions, at a concentration of 1.0-5.0 g dm-3 in 10-50-mm3 aliquots (10-250 pg of sample) of eluent. The columns were eluted at a flow- rate of 2-5 cm3 h-l with a pressure drop of 5&250 p.s.i. The column effluent was led via PTFE tubing to an externally thermostated Waters Associates Model R401 differential refractometer coupled to a standard Servoscribe IS chart recorder.At maximum instrument sensitivity, column loadings down to 1 pg of sample could be analysed reliably. Column Efficiency In order to ascertain the potential of PAPM as a universal GPC packing, its performance in water and benzyl alcohol was investigated.The typical polydisperse polyethylene glycol (Carbowax 200) was readily resolved into its discrete oligomers in both solvents (Fig. 2). In each profile, the peaks 1,2 and 3 have been assigned respectively to ethylene glycol, diethylene glycol and triethylene glycol, respectively, by chromatographing these solutes independently.I Blue 5 14 Dextran 11 I I I (6) Polystyrene 10 15 20 Elution volume/cm3 L - , - J I I I I I 0.00 0.25 0.50 0.75 1.00 1.25 Absolute distribution coefficient, Kd Fig. 2. Elution profiles for Carbowax 200 in (a) water and (b) benzyl alcohol. The general formula for Carbowaxes is HO(-CH,CH,O-) =H.June, 1977 GEL PERMEATION CHROMATOGRAPHY 137 The Wheaton and Bauman3 absolute distribution coefficient, K,, was calculated in the instance of each oligomeric solute from the following relationship : where Ve, V , and Vo are the elution volumes of the given solute, the solvent and a totally excluded solute, respectively.The solvent elution volume, Vs, for the water and benzyl alcohol columns was measured by elution of either deuterium oxide or pentadeuterobenzyl alcohol.These solutes could be detected conveniently by the differential refractometer and were assumed to have similar physico-chemical properties to those of the respective solvents. The void volume, Vo, was obtained by elution of Blue Dextran 2000 (ZW = 2 x lo6) or polystyrene (m, = 2 x lo6), as appropriate. The Kd values obtained are indicated by the scale superimposed directly on the elution profiles. The efficiencies of PAPM columns packed in water and benzyl alcohol were compared by calculating the number of theoretical plates per metre, E , for the appropriate deuterated solvent from the following relationship4 : 16 V , E = - - L (d where L is the column length and w is the peak width.At higher operating temperatures, PAPM was more efficient in benzyl alcohol than in water, but this situation was reversed at lower temperatures (Table I).Almost certainly, the more marked loss in efficiency in benzyl alcohol is caused by the relatively greater increase in viscosity of this solvent compared with that of water on decreasing the temperature. The high efficiencies that can be obtained in the organic solvent fully justifies increasing the lipophilic character of the matrix, as compared with poly(acryloylmorpho1ine) (Enzacryl -Gel), by the incorporation of proline residues.Organic xerogel packings derived from Enzacryl Gel give, overall, much lower column efficien- cies than the corresponding aqueous xerogel~.~ TABLE I DEPENDENCE OF COLUMN EFFICIENCY ON TEMPERATURE IN GPC WITH POLY (ACRYLOYLPROLYLMORPHOLINE) COLUMN PACKINGS The column efficiency was measured for the isotopically labelled solvent peaks, D,O and pentadeuterobenzyl alcohol.Solvent Water Benzyl alcohol Column efficiencylplates m-1 r A > 0 "C 20 "C 40 "C 60 "C 3 980 6 340 7 880 11 300 1290 5 060 9 110 11 600 Potential of PAPM as a GPC Material For example, hydrophilic solutes such as oligosaccharides and urea - formaldehyde resin precursors are separated readily in water. Both aromatic and simple hydrocarbon solutes can be resolved in benzyl alcohol. Carboxylic acids, amines and amino-acid derivatives can also be chromato- graphed, although in certain instances some sorptive interaction is evident. PAPM forms good xerogel packings with other organic solvents, such as chloroform, dimethylformamide, pyridine and dioxan.References Typical GPC behaviour on PAPM is observed with a wide variety of solutes. Further work will include the GPC evaluation of PAPM in these solvents. 1. 2. 3. 4. 5. Joustra, M., Soderqvist, B., and Fischer, L., J . Chromat., 1967, 28, 21. Epton, R., Holding, S. R., and McLaren, J. V., Polymer, 1976, 17, 843. Wheaton, R. M., and Bauman, W. C., Am.. N . Y . Acad. Sci., 1953, 57, 159. Martin, A. J . P., and Synge, R. L. M., Biochem. J . , 1941, 35, 1358. Epton, R., Holloway, C., and McLaren, J. V., J . Appl. Polym. Sci., 1974, 18, 179.

ISSN:0306-1396    

DOI:10.1039/AD9771400135

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

138 ON-LINE TECHNIQUES FOR PROCESS MONITORING Proc. Analyt. Div. Chem. SOC. 0 n = I i ne Tech n iq ues for Process Monitoring The following are summaries of two of the papers presented at a Meeting of the Analytical Division organised by the Automatic Methods Group held on February 2nd, 1977, at the Warren Spring Laboratory, Stevenage, Hertfordshire. Automatic Control of Waterside Chemical Conditions in Power Station Boilers Using Conductivity Measurements T.P. Smith Scientijic Services Department, CEGB, North Eastevn Region, Beckwith Knowbe, Otley Road, Havvogate, North Yorkshire, HG3 1PR The risk of waterside corrosion in power station boilers can be minimised by careful chemical control of the boiler water and the maintenance of a high standard of feed-water quality. Application of CEGBl policy for chemical control has resulted in a considerable reduction in corrosion failure over the last 12 years.The North Eastern Region of CEGB has developed an automatic instrument that applies this policy throughout the 24 h of each day. The system is applicable to conventional drum boilers using sodium hydroxide for chemical conditioning. It cannot be used for the control of phosphate conditioning or for once-through units.Boiler water is analysed by measuring the conductivity of a continuously flowing sample before and after cation exchange. Inorganic salt and alkali concentrations are calculated independently from the conductivity measurements. The signals produced are used to control boiler water chemical conditions automatically by operation of the blowdown valve and boiler dosing pump.An alarm system is provided to indicate abnormal conditions and instrument failures. Condensate purity is monitored by using conductivity measurements before and after cation exchange. The main part of the equipment is housed in a cubicle measuring 2 m high x 1 m square. One such cubicle is used for each generator together with dissolved oxygen and silica analysers, a feed dosing flow failure alarm, blowdown valve, boiler dosing pump and chart recorder.Measurement System In the North Eastern Region salts are not used for boiler water treatment at pressures over 60 bar. Feed- and boiler waters normally contain small amounts of alkalis added deliberately for pH control and salts that are impurities.The system uses conductivity measurement before and after cation exchange to calculate these two components independently. When a water sample flows through a bed of cation-exchange resin in the hydrogen form, any alkalis in the sample are converted into water, which is only feebly ionised and gives a negligible contribution to the conductivity of the solution. Any salts present are converted into the corresponding acids.This gives a three-fold increase in conductivity owing to the high mobility of the hydrogen ions in the acidic solution compared with the cations in the original salt solution. In condensate analysis, cation exchange removes the ammonia normally present, thus lowering the limit of detection for salts, as small concentrations are no longer masked by the conductivity due to dissociated ammonium hydroxide.The conductivity measurement made before cation exchange is used to give a rapid alarm when the condensate is grossly contamin- ated. The measurement after cation exchange gives a more sensitive alarm, which is delayed for the time taken for the sample to pass through the cation-exchange columns. In boiler water analysis, the conductivity before cation exchange is due to both salts and alkalis in the sample.The conductivity due to the salts is calculated from the conductivity of the acids formed from them by cation exchange. This value is subtracted from the total conductivity of the boiler water in order to determine the conductivity due to alkalis and hence the alkalinity of the boiler water.The salts present in high-pressure boiler water are mainly chlorides, sulphates, silicates and nitrates. As chlorides are the main potential hazard in boiler corrosion, a variable, pre-set proportion of the conductivity due to all salts except silicates is used to calculate the chlorideJune, 1977 ON-LINE TECHNIQUES FOR PROCESS MONITORING 139 concentration. The proportion chosen is checked by comparison of the calculated chloride with results from manual chemical analyses.Blowdown Control to reduce the salt concentration. Alarm and Control System The boiler blowdown valve opens at a pre-set level in the range 0-5 p.p.m. as sodium chloride The hysteresis is fixed at 1% for all control settings. Boiler Dosing Control “Coarse control” is obtained when the dosing pump starts to inject alkali at a pre-set concentration and stops when the concentration in the sample has risen by 1% of the control setting.This system is satisfactory if slow injec- tions of dilute alkali can be used. The “fine control’’ dosing system is used if large pumps must be used. The pump operates for a fixed time to inject sufficient alkali to raise the alkalinity by 0.5-1 p.p.m.as sodium hydroxide. The system is re-set automatically, ready for future injections, if the first injection is successful. An alarm is given if automatic dosing fails to increase the alkalinity. A switch is used to choose whether fine or coarse control dosing is to be used. Two systems of dosing control are provided. Protection against Instrument Failure The logic system incorporated in the instrument is designed to control the operation of the condensate and boiler water analysers and to ensure that false alarms and control actions do not result from the more common instrument malfunctions.Alarms are given for power supply and sample flow failures and chemical alarms are inhibited for a few minutes to allow restoration of normal conditions after these failures.Exhaustion of the cation-exchange columns is detected by using two columns in series. The conductivity is measured at the outlet of each column and the values are compared. When a difference of more than 10% persists for more than 30 min the sample flow is switched automatically to the second column and the exhausted column is by-passed.A sample high- temperature alarm is fitted to the boiler water sampling system. This also stops the flow of hot sample through the analyser. Protection against Unsatisfactory Plant Conditions It is important that these functions should not occur at times when a plant hazard could exist. Boiler blowdown is inhibited automatically when the level in the reserve feed-water tanks is too low to provide the necessary make-up for the system.Boiler dosing is inhibited when the dosing storage tank is empty and both blowdown and dosing are inhibited when boiler load conditions are unsuitable. Part of the logic system is used to control boiler blowdown and chemical dosing. Alarm Display System 15 of which are used for alarm indications originating within the system.may be used for alarms from other chemical instruments. An alarm annunciator unit is provided in the instrument cubicle. This unit has 24 channels, The spare channels Measurement Display and Recording System impurity contaminate the condensate. shows two small peaks. the blowdown valve opens to restore it to its original value of 1 p.p.m. alkalinity of the boiler water decreases and two injections of sodium hydroxide are made.Fig. 1 is a chart record showing the operation of the system when two small amounts of The condensate conductivity after cation exchange This contamination causes an increase in boiler water salinity and During this period the System Reliability The mean time between failures (MTBF) for the first 142 000 cubicle-hours after com- Most of the failures missioning was 1500 h, with only minor variations between stations.occurred in dosing pumps, sampling systems and blowdown valves.140 Proc. Analyt. Div. Chew. SOC. A comparison was made between the actual MTBF for the electronic part of the system over a period of about 200 000 cubicle-hours, run both before and after commissioning, with the MTBF calculated from component life data.2 The calculated figure was 8900 for one cubicle compared with the observed MTBF of 9100 h.ON-LINE TECHNIQUES FOR PROCESS MONITORING Fig. 1. Recorder chart from automatic chemical control monitor. Fault Finding Using the CEGB’s “Fault Step” System A method of logical diagnosis for faults in various complex systems has been developed by the Engineering Services and Operations Departments of the CEGB London Headquarters.3 This method, which can be applied universally to complex systems, has been called “Fault Step.” It breaks the fault-finding procedure down into a series of five hierarchical levels, starting from the “general” and proceeding to the “particular.” At each level the fault finder is presented with the information necessary to proceed to the next level, thus eliminating the need for highly specialised training or detailed knowledge of the equipment.“Fault Step” documents have been produced €or the automatic chemical monitoring and control system. These are expected to make a major contribution towards rapid detection and repair of failures. The author thanks the Director General, North East Region, CEGB, for permission to publish this paper.References 1. Generation Operation Memorandum No. 72, CEGB, London, 1967 and 1976. 2. Sandle, P. J., “Electronic Components Failures in CEGB Stations,” CERL Note No. RD/L/N177/74, 3. “Introduction to the Fault Step Concept of Logical Fault Diagnosis,” CEGB, London, 1972. CERL, Leatherhead, 1974.June, 1977 ON-LINE TECHNIQUES FOR PROCESS MONITORING Fast Titrations in Flow-through Systems 141 B.Griepink and H. Verbruggen Analytical Chemistry Laboratory, Free University of Utrecht, Croesestraat, 77A Utrecht, The Netherlands. Department of Electrical Engineering, Delft University of Technology, Mekewej 4, Delft, The Netherlands. Titration methods have several advantages, such as simplicity and the production of absolute results, and it could be advantageous to use titration systems in flow-through measurements.However, titration methods are time consuming and, if the time needed to complete a titri- metric measurement exceeds the lifetime of the concentration changes to be measured, the titration is useless. Hence it was desirable to reduce titration times of several minutes to about 10 s or less. The control engineering model necessary for the design of a controller also leads to a better under- standing of the titration procedure and the processes involved in it.For the modelling neces- sary for the design of a controller, one has to know the static and dynamic properties of the several components of the control loop, the combination of which yields the over-all static and dynamic behaviour of the system.To measure these properties, one uses step response or frequency response measurements. In both instances the static and dynamic behaviour of as many of the components as possible are measured as the output upon supplying a step signal or a frequency signal at the input. The input - output relationship is called the transfer function and the transfer function of a first-order detection, Y , = 1 - e-t/T, upon a step signal ( X , = 1) is H , = 1 - e-t/T.The over-all transfer function of a few combinations of blocks in a loop is shown below. In order to accelerate a titration it is necessary to use control engineering techniques. yYpY Y=HX 7 - q ~ . Y "feedback" In the modelling stage, all transfer functions are combined to yield a model described by In order to simplify the mathematical relationships, the over-all transfer function, Htot.Laplace transformation is used. The general form for Htot in most titrations is b o p + blPm-l+ b2Pm-2 + . . . +l)e-pTn +I aopn + alpn--l + a2pn-2 + . . . where K is the gain and TD the dead-time. This equation can be rewritten as The roots p = -xi are called the zeroes and the roots p = -pj the poles of the system.The resulting model is fed into a computer. Several mathematical functions can be inserted142 Proc. AnaZyt. Div. Chem. SOC. in the loop in the controller block in various simulations. Provided that we wish to accelerate a titration, we can optimise the controller's functions in such a way that the shortest titration time is obtained.We then have to translate the controller's transfer function, expressed in mathematical terms, into a real controller consisting of capacitances, resistors, etc. An example is the coulometric titration of acid in a flow-through system with spectrophoto- metric detection. In this instance we corrected for any turbidity that might occur in the solution and also dilution by added reagents.The model of the titration vessel contained two time constants : ON-LINE TECHNIQUES FOR PROCESS MONITORING ' K1 ' 0.25 + p , I K1 500p + 1 Only the time constant of 0.25 s was taken into account because a titration should be com- The several transfer functions of the blocks from pleted in a time much shorter than 500 s. the functional block scheme were measured: Vessel Detection Controller gen.circ. This yielded a control engineering model of the system : The two dead-times in the loop will cause a considerable delay. Several mathematical functions were tried in the simulation stage and proportional control with a high gain gave good control but a slow titration (about 20 s). A differential lead gave shorter titration times in the simulation but in practice the noise level was too high for the minimum titration time predicted by simulation with the model to be obtained. A non-linear control (controller out- put function: Y , = O.IXt3, where X is the input signal and Y is the output signal) gave the best results, with titration times of about 10 s.The model predicted that the dead-time in the generation part could be reduced by using a smaller generation electrode placed as near as possible to the inlet in the titration vessel.We therefore used a platinum gauze near to the inlet and placed at an angle of 90" to the direction of flow. Titration times of 4 s were then achieved when using an appropriate control. The standard deviation in the range 2-11 nmol of acid was about 0.2 nmol. Another interesting example of the adaptation of control engineering. methods is a study we made of the spectrophotometric titration of Zn2+ ions with EDTA using xylenol orange as the indicator. This titration could be carried out in a few seconds with a controller designed after modelling and simulation studies. An interesting detail is that we found evidence that a shift in chemical equilibrium was mainly responsible for the over-all titration time found. This result could mean that a further decrease in titration times could be obtained, e.g., by increasing the temperature. This example shows again that analytical chemists and control engineers must co-operate closely in order to obtain the best results.

ISSN:0306-1396    

DOI:10.1039/AD9771400138

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

June, 19 7 7 SOURCES FOR EMISSION SPECTROSCOPY Sources for Emission Spectroscopy 143 The following is a summary of one of the papers presented at a Joint Meeting of the North East Region and the Atomic Spectroscopy Group held on October 28th, 1976, at The Cleve- land Scientific Institute, Middlesbrough. Is Optical Emission Spectrometry Being Tailored to the Requirements and Budgets of a Large Variety of Users?-Plenary Lecture P.W. J. M. Boumans Philips Research Laboratories, Eindhoven, The Netherlands This Lecture is in some respects a review of reviews.l-13 The basic question is whether new developments have widened the scope of optical emission spectrometry (OES) so that it can be used for applications and in fields from which it was formerly excluded. For considera- tion of this question the routine analysis of metals and alloys will be taken as a convenient starting point.The use of a “spark” source and a multichannel emission spectrometer is the most firmly established OES method. (“Spark” denotes here any intermittent discharge of either the condensed or non-condensed type, but see references 14 and 15.) Two papersl6,l7 presented at this Meeting dealt with aspects of spark emission spectrometry.In the present discussion we add only that the spark emission spectrometer represents a complete analysis instrument that fulfils the demands of a particular group of users. We may then ask what modifications are necessary and possible in order to adapt this instrument to the demands of other groups of users. We shall approach this question by splitting up the complete spectrometer into the “signal generator,’’ i.e., the excitation source, and the “signal processor,” i.e., the system en- compassing the dispersion optics and the devices for detection, read-out and data handling.The principal excitation sources are the following. (i) “Spark.” (ii) Glow discharge lamp (GDL). (iii) D.c. arc. (in) “Plasma sources” for solution analysis : (a) d.c.plasma jet; ( b ) gas-stabilised arc ; ( c ) (d) (e) microwave-induced plasma (MIP). (v) Flame. (vz) Laser. (vii) Hollow-cathode discharge. (i) radiofrequency inductively coupled plasma (ICP) ; capacitively coupled microwave plasma (CMP) ; The “signal processors” can be conveniently listed as follows- Polychromators, one-dimensional dispersion with fixed optical components : (a) large polychromators (direct readers) with multiple exit slit and multiple detector (PMT) or multiple exit slit and single detector (PMT) or a single movable exit slit and a single detector (PMT); ( b ) large or small polychromators with exit slits replaced by multiple arrays of photo-diodes, each consisting of a few (e.g., ten 30pm wide) photo-diodes for measurements of the line peak and the background.ls-20 Echelle spectrometers, two-dimensional dispersion with fixed optical components21@ : (a) multiple exit slit and single detector (PMT) design, “spinning encoding disk” ; (b) multiple exit slit and multiple detector design, cassette with fixed apertures, mirrors and PMTs; (c) with television-camera tube (and image converter)lo,12@-3* ; (d) with image dis~ector.~g-~~ (ii)144 (iii) (iv) SOURCES FOR EMISSION SPECTROSCOPY Proc.AnaZyt. Div. Chem. SOC. Spectrographs, one-dimensional dispersion with photographic detection completed with : (a) manual microphotometer ; (b) recording microphotometer; (c) computerised automatic micro photometer. 43344 Monochromators, one-dimensional dispersion with mechanically movable optical component(s) for wavelength adjustment : ( a ) single exit slit and single detector (PMT) design with wavelength control as follows- manual scanning slewing and programmable with precision mechanical d e v i ~ e ~ ~ , ~ ~ slewing and programmable with computer or micropro~essoI““~~~ ; (b) without exit slit, with television-camera or self-scanning linear photo-diode The potentials of each of these signal processors can be expressed in terms of characteristics such as : mode of measurement, simultaneous or sequential ; wavelength range ; spectral resolution ; number of addressable “spectral windows” (analysis and reference lines, wave- lengths for background measurement) ; signal to noise ratio ; dynamic range; programmability, flexibility in the choice of “spectral windows’’ ; feasibility of “true” background correction ; compatibility with the properties of the excitation- source ; stability; reliability; state of the art.Signal Generators : Excitation Sources Glow Discharge Lamp If we replace the spark by a GDL of the Grimm type,53,54 the matrix effects associated with both the atomisation of the solid and the excitation of the atomic vapour can be substantially reduced, as has been shown by, for example, Dogan et aL55 and Radmacher and de S ~ a r d t .~ 6 Consequently, one set of calibration graphs can be employed for materials that vary widely in composition. An improvement of the precision with respect to the high repetition rate spark in the analysis of steel has been reported and it has been shown, also for steel samples, that an analysis time as short as 15 s is feasible.56 A glow discharge spectrometer might thus be a useful alternative to the spark spectrometer.Other wave- length settings will often be required57 and some signal to noise ratio problems may arise as the GDL spectra have low intensity. The literature does not provide evidence that the potential of the GDL for the analysis of metals has been sufficiently explored and therefore the paper presented at this Meeting about the development of GDL OES for application in the steel industry is welcome.58 Thin film analysis Among the authors concerned with investigations of the GDL for thin-film a n a l y s i ~ ~ ~ - ~ ~ we mention particularly Greene and co-w~rkers~~@; their work appears to be the most advanced in this field.The literature shows that GDL OES permits thin-film analysis including depth profiling of concentrations. The determination of major, minor and even trace constituents, down to the parts per million level, has been documented, and it has been shown that the results of GDL OES correlate with those obtained by scanning electron microscopy.One funda- mental limitation that appears to be the ultimate limit to depth resolution should be borne in mind, however: after initiation of the discharge there is a transient period that precedes steady-state sputtering conditions. The temporal variations of the line intensities measured during this transient period are not representative of the existing compositional variations with depth, but reflect primarily the changes in the surface topography produced by the sputtering process.They developed a GDL of a different design from that developed by Grimm. Universal analysis in non-conducting powdered samples, Laqua et ~ 1 . ~ 9 ~ ~ developed a universal method for the determination of major constituents The sample is ground to a grain size smaller thanJune, 1977 SOURCES FOR EMISSION SPECTROSCOPY 145 50 pm, diluted with copper powder and pressed into a pellet.This pellet is clamped in the water-cooled holder of the cathode block of the GDL. Laqua’s work provides sound argu- ments for the use of the GDL as an excitation source for the universal analysis of non- conducting materials. This raises the question of whether and to what extent the GDL is competitive with the ICP for solution Inductively Coupled Plasma A paper was presented by Greenfield66 on the ICP investigated in his laboratory and i t was shown that he had successfully used this ICP for many years for routine analysis of almost any type of material.I have no difficulty in supporting Greenfield’s arguments as to the “analytical power” of ICPs in general, although I differ in my opinion on the pre- ferred power input, frequency and gaseous atmosphere and about the nature of some fundamental processes and their significance for the analytical capabilities of the ICP.67 The current l i t e r a t ~ r e l - ~ ~ ~ , ~ ~ ~ ~ ~ ~ ~ * shows that ICPs are of increasing interest in many fields and can be considered as excellent tools for simultaneous multi-element analysis of solutions and solids (the latter after dissolution). We can expect that technological advance- ments and application studies as well as the interaction between the manufacturers of commercial ICP apparatus and the users of such equipment will rapidly lead t o optimised standard instruments and established and reliable analysis methods for a large variety of materials.Of particular interest is an assessment of the ICP as a source for universal analysis in relation to the GDL and the classical d.c. arc. Comparison of ICPs, the GDL and the D.c. Arc for Universal Analysis Comparing ICPs, the GDL and the d.c. arc as excitation sources for universal analysis and assessing which of them is to be preferred is not easy, for the preference of a particular user will depend on the situation in the relevant laboratory, including the types of sample to be handled and the infrastructure of the laboratory. For a solution technique (ICP) a wet- chemical method is indispensable and an experienced wet-chemical analyst should be TABLE I TENTATIVE COMPARISON OF THE GLOW DISCHARGE LAMP (GDL), THE INDUCTIVELY COUPLED PLASMA (ICP) AND THE DIRECT CURRENT ARC (DCA) AS EXCITATION SOURCES FOR UNIVERSAL ANALYSIS The + and - signs represent an evaluation of the factors given in the left-hand column. GDL ICP DCA + + - - Ease of liquid-sample analysis _ _ Ease of solid-sample analysis + - + + (+) Accuracy + + + + - (+I Detection limitst - + + + + Time needed for intensity measurement Cost of consumed materials - + _ - + + - _ - Detection limits for a theoretical spectral resolution of approximately 100.000 : GDL, 1-100 p.p.m.(pg 8-l) in the solid sample for 20-min exposures; ICP, 0.1-100 ng ml-l in the solution or 0.01-10 p.p.m. (pg g-l) in the dissolved solid sample (1% m/V) for 15-s integrations; DCA, 1-100 p.p.m. ( p g g-l) in the solid sample for 2-min exposures.available. In addition, the easier standardisation and consequently the potentially higher accuracy of a solution technique should not be outweighed by the disadvantages associated with the necessity of dissolving solid samples. If, however, there is a need for solution analysis because many samples become available in the form of solutions, the decision as to which method is to be adopted is made easier.Table I is a comparison of the use of ICPs, the GDL and the d.c. arc. Six factors are considered : ease of liquid-sample analysis ; ease of solid-sample analysis as dictated by the * References to work on ICP OES cited here include only reviews on the subject and it is not intended to give a comprehensive literature survey.146 Proc. A nalyt.Div. Chem. SOC preparation of samples and standards ; accuracy; detection limits ; time required for intensity measurements; and cost of consumed materials such as gases, diluents (copper powder in GDL analysis), chemicals in general and carbon electrodes (d.c. arc analysis). Evidently, as liquid analysis with a GDL is troublesome, though not impossible,68 the ICP must be considered the more universal of the two.The chief advantages of the GDL are seen to be the simpler sample preparation for solids and the lower cost of consumed materials. If these factors are preponderant and one decides for this reason for the GDL, the possibility of convenient liquid analysis and part of the detection power (and therefore the possibility of reducing matrix effects by sample dilution) will have to be sacrificed.The major advantage of the d.c. arc is the simple sample preparation for solids and the major disadvantage is the poor accuracy. If both the samples and the standards are fused (with lithium metaborate) prior to analysis, part of the ease of sample preparation is negated, but there is a substantial gain in accuracy as has been shown by some systematic studies in the trace analysis of geological standard reference material~.~9-~1 The most important feature of a universal d.c.arc method is that it can give a survey of the elemental composition of any solid sample with a minimum amount of sample prepara- tion and a small risk of contamination. Such a survey often suffices or is the step that precedes a more accurate analysis involving particular constituents.Therefore, in spite of new developments in OES, the d.c. arc method is justifiable (also economically) if there is a need in the laboratory for such survey analyses of a large variety of samples. A pre- requisite for the application of universal d.c. arc methods is the existence of an elaborate analysis system in the laboratory and the availability of experienced analysts capable of interpreting the often complex spectra.Under those conditions it becomes advantageous to proceed to automatic analysis of photographically recorded d.c. arc ~ p e ~ t r a ~ ~ , ~ ~ , or to the use of more sophisticated direct readers using a ~ i d i ~ ~ n ~ ~ , ~ ~ , ~ ~ - ~ ~ or an image dissector t ~ b e ~ ~ - ~ ~ as detector.We can expect that the ICP and/or the GDL will gradually find application as a replace- ment of or supplement to the d.c. arc for universal analysis. The properties of these sources (in particular the high temporal stability, the small matrix effects and the large linear dynamic range) will make it possible to set up analysis schemes in which substantially fewer trade- offs are required than in d.c.arc methods. The ICP and GDL inspire confidence that the work involved in line selection, spectral interference checking and calibration for universal analysis will be repaid by the final results. As many reference samples will be needed to deal adequately with spectral interference checking and calibration, it is likely that the convenience of preparing such reference samples in the form of solutions will eventually make the ICP a preferred source for universal a n a l y s i ~ .~ y ~ , ~ ~ - ~ ~ SOURCES FOR EMISSION SPECTROSCOPY Alternative “Plasma Sources” The l i t e r a t ~ r e ~ ~ ~ - 7 ~ ~ ~ ~ ~ 8 has shown that ICPs as “plasma sources” for solution analysis are superior in all analytical respects to d.c. plasmas (DCP) and capacitively coupled micro- wave plasmas (CMP) .The microwave-induced plasmas (MIP) have properties, however, that might make them an interesting and possibly cheaper alternative to ICPs in certain fields of application, in particular the analysis of small amounts of ~arnple.~~-s~ In spite of their superiority it is not impossible to obtain excellent analytical results with sources other than ICPs, for instance DCPs and CMPs.An example is the work of Govin- daraju et aZ.88 : using appropriate dissolution, buffering and standardisation techniques these workers developed a highly satisfactory method of analysis for silicate rocks on the basis of a CMP. To conclude, notwithstanding the successes of individual workers with some alternative plasma sources for solution analysis, the present trend toward commercialisation of ICPs fosters the expectation that ICPs will rapidly gain ground so as to push the alternatives, except for the MIP, into the background.Signal Processors : Spectrometers We may ask whether it is possible to design spectrometers such that they can automatically and reliably handle emission spectra of varying complexity and whether so much diversifica-June, 1977 SOURCES FOR EMISSION SPECTROSCOPY 147 tion can be brought to these instruments that both the large and the small users get systems that fit their needs and budgets.Automatic Evaluation of Emission Spectra In our laboratory we developed a microphotometer for completely automatic analysis of photographically recorded emission spectra43 as obtained in the d.c.carbon arc method developed by Addink.89 The system encompasses the microphotometer itself and an on- line computer. The blackening is measured at 5-pm intervals and the position of each measurement is accurately determined by using a reflection phase grating. The 50000 data from the positions and blackenings of lines and background from a 25 cm long spectrum are reduced by the on-line computer during the scanning.The final data are limited to peak and background measurements in 400 spectral windows, which represent the 400 spectral lines inherent in this universal d.c. arc method. The method covers 66 analysis elements in a large variety of matrices, in principle any matrix. The data reduction comprises qualitative analysis by an iteration procedure using interference tables stored in the computer memory, and eventually a quantitative analysis using known sensitivities.The development of this system was started at a time when the photographic plate was the only detector that could cope with the required number of spectral windows. We may now raise three questions: Are better alternatives for multichannel detection now available ? Are 400 spectral windows needed for any universal method? How is the number of spectral windows reduced when the requirement of uni- versality is dropped and a smaller number of analysis elements and matrices is of interest? A 25 cm long spectrum is scanned at a speed of 1 cm s-l.(i) (ii) (iii) Alternatives An echelle spectrometer equipped with an image converter and a vidicon tube such as proposed by Margoshes in 197023-25 and later explored, for instance, by Wood et a1.,30 is an obvious alternative.It appears that not all of the technological problems have been com- pletely overcome, but one can expect further progress in the near future. Another alternative is the echelle spectrometer provided with an image dissector tube, the so-called IDES system, developed by Danielsson and c o - w o r k e r ~ .~ ~ - ~ ~ This system is available commercially. All these instruments, including computerised microphotometers, offer the most flexible and universal approach to spectrochemical data taking and handling. Both hardware and software development, however, are very expensive. Required number of spectml windows The minimum number of windows depends on six factors, viz.: (i) (ii) (iii) (iv) (v) (vi) Clearly, the dynamic range as dictated by the detector can be considerably improved if a photomultiplier or a solid-state device instead of a photographic emulsion, and a digital instead of an analogue measuring technique are used. Also, the linear dynamic range as dictated by the source can be extended if, for example, a d.c.arc is replaced by either an ICP or a GDL, although the spectral lines emitted from an ICP or a GDL are not entirely free of self-absorpti~n.~~-~~ Both these extensions of the dynamic range will reduce the required number of spectral windows as they tend to enlarge the concentration range that can be covered with one and the same analysis line.the number of analysis elements of interest; the concentration ranges to be covered; the types of matrices to be handled; the useful dynamic range of the detector; the linear dynamic range as dictated by the source (self-absorption); the spectral resolution of the spectrometer.148 SOURCES FOR EMISSION SPECTROSCOPY Proc. AnaZyt. Div. Chem.SOC. The severest problem is associated with the coverage of matrices, not primarily because of physical or chemical interferences, but because of line coincidences. Here a compromise must be found between the spectral resolution of the instrument and the number of spectral windows to be adopted. However, for a truly universal analysis method a large number of spectral windows is indispensable.Dropping universality If universality is dropped, the number of spectral windows can be reduced substantially. This reduction is permitted when a limited variety of fixed analysis problems has to be faced. Presumably most of the analysis problems to be handled by OES will belong in this category and the most adequate signal processor is then the conventional direct reader operating in a simultaneous mode of measurement.This spectrometer is still unequalled for many routine applications. It has one major disadvantage, however, namely the lack of flexibility as to the choice of analysis lines and thus the coverage of both analytes and matrices once the instrument has been installed. Further, there are trends toward improving the performance of direct readers, as is evidenced by the consideration that is presently given to stray-light reduction (stray light can impose severe limitations in trace analysis with an ICP)133g3,94 and background correction by using measurements in the close vicinity of the analysis l i n e ~ .~ ~ , ~ 8 - 2 0 , 4 ~ , 4 8 3 9 5 - 1 0 2 Particular mention must be made of the progress made by Bubert and Hagenah20 in the development of amplifiers for photo-diode arrays of the type described by Boumans and c o - w ~ r k e r s .~ ~ ~ ~ ~ These photo-diode arrays, which should be distinguished from the self- scanning arrays explored by, e g . , Horlick and C ~ d d i n g , ~ ~ , ~ ~ appear to be promising for the development of spectrometers that could bring simultaneous multichannel emission spectro- metry within reach of those users for whom the existing emission spectrometers are too large (and too expensive) and for whom the present-day sequential atomic-absorption spectro- metric instrumentation does not provide an entirely satisfactory solution to their problems.Flexible Analysis : Programmable Monochromator An interesting question is whether a medium-type direct reader can be replaced by a medium-type instrument that offers a large degree of flexibility, such as computerised programmable monochr~mators.~~-~~ Basically a programmable monochromator is a monochromator for automatic sequential measurements at various wavelengths, whereby the scanning mechanism has been replaced by a slewing mechanism that enables the wavelength setting to be rapidly slewed to any desired spectral window so that measuring time can be virtually completely used for measurements at relevant wavelengths only.In the computerised v e r ~ i o n , ~ ~ , ~ * the computer is used to control the program during an analysis and more essentially to check and control the correctness of wavelength positioning. This approach permits not only a simpler and cheaper mechanical design, but also provides for automation of the programming itself in the instance of new analytes and/or matrices. Obviously the sequential mode of measurement limits the applications: first, one is bound to a source that provides signals that are constant in time for a period of up to several minutes, a condition that is satisfied by excitation sources such as ICPs, MIPS and GDLs; and secondly, the number of analytes to be covered in one sample is limited by the maximum permitted analysis time and/or the available amount of sample.Conclusion Is OES being tailored to the requirements and budgets of a large variety of users? The conclusion is that OES can face the needs and budgets of all those who want a lot and can afford a lot and that it is being tailored to the requirements and budgets of the more modest users.The advent of excitation sources such as ICPs for the analysis of solutions and GDLs for the analysis of both metals and non-conducting powders makes OES fitted to tackle problems for which atomic-absorption spectrometry might still be preferred. The main reason for this preference is that the results are reliable, in part owing to the high selectivity of atomic- absorption spectrometry, and that the technique is cheap in respect of both apparatus and operator cost.The technique is only cheap, however, to the extent that only a few elementsJune, 19 7 7 SOURCES FOR EMISSION SPECTROSCOPY 149 have to be determined in one sample and that relatively simple samples have to be analysed.If the samples are complex and consequently require elaborate pre-treatment, the personnel cost involved in sample preparation and standardisation weigh more heavily. These costs could be reduced drastically if ICP OES or GDL OES were used. This step can only be a definitive gain, however, if the profits of a reduction in sample-treatment cost are not balanced or outweighed by an increase in signal-processing cost, in other words, if an experienced wet- chemical analyst need not be replaced by an experienced emission spectroscopist who is able to deal with complex spectra so as to prevent spectral interferences from endangering the reliability of an analysis.Generally no problems will arise in this respect when the required flexibility is low.A spectrometer, whatever its basic design, can be adequately programmed to deal with a fixed and limited set of envisaged problems. In this field, we indicated the maturing of the classical direct readers so that they would better fulfil the requirements of users with large or moderate budgets and we pointed to the promise that photo-diode arrays have for the development of spectrometers that could fit the require- ments of those with small budgets.If more flexibility than that which can be achieved with direct readers is needed, a spectro- meter should be able to perform automatically those checks that an experienced emission spectroscopist would perform. 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W., and Raycheba, J . M. T., Rusch, K. W., Howell, N. G., and Morrison, G. H., Analyt. Chem., 1974, 46, 1231. scopy, Melbourne, 1975. scopy Group of the Analytical Division of The Chemical Society, October, 1976.Spectroscopy Group of the Analytical Division of The Chemical Society, October, 1976. 1973, 28B, 227. 1976. Analyt. Chem., 1974, 46, 374.150 SOURCES FOR EMISSION SPECTROSCOPY Proc. AnaZyt. Div. Chem. SOG, 34. 35. 36. 37. 38. 39. 40. 41. 42. Schagen, P., J . Phys. E, 1975, 8, 153. Knapp, D. O., Omenetto, N., Hart, L.P., Plankey, F. W., and Winefordner, J. D., Analytica Clzim. Howell, N. G., Ganjei, J . D., and Morrison, G. H., Analyt. Chem., 1976, 48, 319. Njeman, T. A., and Enke, C. G., Analyt. Chem., 1976, 48, 619. van der Piepen, H., Claase, C . , and de Villiers, D. B., Spectrochim. A d a , 1976, 31B, 389. Golightly, D. W., Kniseley, R. N., and Fassel, V. A., Spectrochim. Acta, 1970, 25B, 451.Danielsson, A., and Lindblom, P., Phys. Scr., 1972, 5, 227. Danielsson, A., Lindblom, P., and Soderman, E., Chem. Scr., 1974, 6, 5. Danielsson, A., Soderman, E., and Lindblom, P., “Preprints of the 18th Colloquium Spectroscopicum Internationale, Grenoble, 1975,” Volume 2, Groupement pour 1’Avancement des Mdthodes Spectroscopiques et Physico-chimjques d’ Analyse, Paris, 1975, p.488. Witmer, A. W., Jansen, J . A. J., van Gool, G. H., and Brouwer, G., Philips Tech. Rev., 1974, 34, 322. Walthall, F. G., , J . Res. U.S. Geol. Surv., 1974, 2, 61. Malmstadt, H. V., and Cordas, E., Am. Lab., 1972, 4(8), 35. Cordos, E., and Malmstadt, H. V., Analyt. Chem., 1973, 45, 425. Spillman, R. W., and Malmstadt, H. V., Analyt. Chem., 1976, 48, 303. Boumans, P. W. J.&I., van Gool, G. H., and Jansen, J . A. J., Analyst, 1976, 101, 585. Horlick, G., and Codding, E. G., Analyt. Chem., 1973, 45, 1490, 1749. Horlick, G., and Codding, E. G., Appl. Spectrosc., 1975, 29, 167. Fry, P. W., J . Phys. E , 1975, 8, 337. Yates, D. A., and Kuwana, T., Analyt. Chem., 1976, 48, 510. Grimm, W., Naturwissenschaften, 1967, 54, 586. Grimm, W., Spectrochim. Acta, 1968, 23B, 443.Dogan, M., Laqua, K., and Massmann, H., Spectrochim. Acta, 1972, 27B, 65. Radmacher, H. W , and de Swardt, M. C., Spectrochim. Acta, 1975, 30B, 353. Salpeter, E. W., Spektren in der Glimmentladung von 1500 bis 4000 A, Teil I : Fe, Co, Cr, Mo, Nb, Buttenvorth, A., paper presented a t a Joint Meeting of the North East Region and the Atomic Greene, J . E., and Whelan, J .M., J . A@l. Phys., 1973, 44, 2509. Greene, J . E., Sequeda-Osorio, F., and Natarajan, B. R., J . Appl. Phys., 1975, 46, 2701. Belle, C. J., and Johnson, J . D., Appl. Spectrosc., 1973, 27, 118. Berneron, R., and Moreau, J . P., “Preprints of the 18th Colloquium Spectroscopicum Internationale, Grenoble, 1975,” Volume 1, Groupement pour 1’Avancement des MCthodes Spectroscopiques et Physico-chimiques d’hnalyse, Paris, 1975, pp.263 and 268. A d a , 1974, 69, 455. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. Ni, Ta, Ti,” Specola Vaticana, Citt& del Vaticano, 1971. Spectroscopy Group of the Analytical Division of The Chemical Society, October, 1976. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. 73. 74. 75. 76. 77. 78. 79.80. 81. 82. 83. 84. 85. 86. 87. 88. 89. 90. 91. 92. Boumans, P. W. J. M., Analyt. Chem., 1972, 44, 1219. El Alfy, S., Laqua, K., and Massmann, H., 2. Analyt. Chem., 1973, 263, 1. Boumans, P. W. J . RI., “Preprints of the 20th Colloquium Spectroscopicum Internationale and the 7th International Conference on Atomic Spectroscopy, Prague, 1977.” Greenfield, S., paper presented a t a Joint Meeting of the North East Region and the Atomic Spectro- scopy Group of the Analytical Division of The Chemical Society, October, 1976.Boumans, P. W. J . M., and de Boer, F. J., Spectvochim. Acta, B. El Alfi, S., Laqua, K., and Massmann, H., “Preprints of the 17th Colloquium Spectroscopicum Maessen, F. J. M. J., and Boumans, P. W. J . M., Spectrochim. Acta, 1968, 23B, 739.Boumans, P. W. J . M., and Maessen, F. J. RI. J., Spectrochim. Acta, 1969, 24B, 585, 611. Maessen, F. J. M. J., Elgersma, J. W., and Boumans, P. W. J. M., Spectrochim. Acta, 1976, 31B, 179. Nakamura, M., and Shalimoff, G. V., Appl. Spectrosc., 1974, 28, 581. Thomas, C. P., J . Res. U.S. Geol. Surv., 1975, 3, 181. Newland, B. T. N., and Mostyn, R. A., ICP I f . Newsl., 1976, 1, 183.Newland, B. T. N., and Mostyn, R. A., ICP I f . Newsl., 1976, 2, 135. Boumans, P. W. J . M., Spectrochim. A d a , 1976, 31B, 147. Boumans, P. W. J. M., de Boer, F. J., Dahmen, F. J., Hoelzel, H., and Meier, A., Spectrochim. Acta, Larson, G. F., and Fassel, V. A., Analyt. Chem., 1976, 48, 1161. Fallgatter, K., Svoboda, V., and Winefordner, J . D., Appl. Seectrosc., 1971, 25, 347.Kawaguchi, H., and Vallee, €3. L., Analyt. Chem., 1975, 47, 1029. Layman, L. R., and Hieftje, G. M., Analyt. Chem., 1975, 47, 194. Aldous, K. M., Dagnall, R. M., Sharp, B. L., and West, T. S., Analytica Chim. Acta, 1971, 54, 233. Lichte, F. E., and Skogerboe, R. K., Analyt. Chem., 1973, 45, 399. FIicke, F. L., Rose, O., Jr., and Caruso, J . A., Analyt. Chem., 1975, 47, 2018. Skogerboe, R. K., and Coleman, G. N., Appl. Spectrosc., 1976, 30, 505. Kaiser, G., G t z , D., Schoch, P., and Tolg, G., Talan.ta, 1975, 22, 889. Iiirkbright, G. F., paper presented a t a Joint Meeting of the North East Region and the Atomic Govindaraju, K., Mevelle, G., and Chouard, C., AnaZyt. Chem., 1976, 48, 1325. Addink, N. W. H., “DC Arc Analysis,” Macmillan, London, 1971. West, C. D., and Human, H. G. C., Spectrochim. Acta, 1976, 31B, 81. Butler, L. R. P., Kroger, K., and West, C. D., Spectrochim. Acta, 1975, 30B, 489. Human, H. G. C., and Scott, R. H., Spectrochim. Acta, 1976, 31B, 459. Internationale, Florence, 1973,” Volume 11, p. 546. 1975, 30B, 449. Spectroscopy Group of the Analytical Division of The Chemical Society, October, 1976.June, 1977 EQUIPMENT NEWS 151 93. 94. 95. 96. 97. 98. 99. 100. 101. 102. Allemand, C., I C P Inf. Newsl., 1976, 1, 238. Larson, G. F., Fassel, V. A., Winge, R. K., and Kniseley, R. N., Appl. Spectrosc., 1976, 30, 384. Allemand, C., I C P Inf. Newsl., 1976,2, 1. Snelleman, W., Rains, T. C., Yee, K. W., Cook, H. D., and Menis, O., Analyt. Chem., 1970, 42, 394. Nordmeyer, M., Spectrochim. Acta, 1972, 27B, 377. Hieftje, G. M., and Sydor, R. J., Appl. Spectrosc., 1972, 26, 624. Epstein, M. S., and O’Haver, T. C., Spectrochim. Acta, 1975, 30B, 135. Sydor, R. J., and Hieftje, G. M., Analyt. Chem., 1976, 48, 535. Sydor, R. J., Sinnamon, J. T., and Hieftje, G. M., Analyt. Chem., 1976, 48, 2030. Skogerboe, R. K., Lamothe, P. J., Bastiaans, G. J., Freeland, S. J., and Coleman, G. N., A p p l Spectrosc., 1976, 30, 495.

ISSN:0306-1396    

DOI:10.1039/AD9771400143

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

June, 1977 EQUIPMENT NEWS 151 Equipment News Piezoelectric Vibration System Lee Engineering Ltd. introduce the Real Time Integrator, Model SC1-400, made by Vibra- Metrics Inc. for use with their Vibramite series of miniature accelerometers t o facilitate the measurement of acceleration, velocity and displacement. The miniature piezoelectric accelerometers possess integral head amplifiers to provide an output in millivolts per “g” from a 1200-L2 source, thereby eliminating the need for expensive charge amplifiers.Sensitivity is no longer a function of cable length or capacity and triboelectric noise is also eliminated. With a 100 mV per “g” input the Model SC1-400 integrator provides simultaneous out- puts of 100 mV per “g” over the range 1 Hz- 10 kHz, 100 mV in-l s-1 over the range 5 Hz- 8 kHz and 10 mV mm-l over the range 10 Hz- 1 kHz with an output impedance of 600 0.Optional galvo drive outputs, selectable gain plus plug-in HP - LP filters are available. Lee Engineering Ltd., Napier House, Bridge Street, Walton on Thames, Surrey, KT12 1AP. Process Monitors The 400A series of digital Trendicators made by Doric Scientific S.A. is available.The incorporation of a new proprietary LSI chip allows the Trendicator function to be changed from a thermocouple to a current or voltage indicator. Change of function is accommodated by plug-in modules covering nine thermocouple ranges and two platinum RTD ranges with a resolution of 0.1 “C. There are two current ranges with resolution of 0.01 yo and four voltage ranges with a resolution of 1 mV.The Digitrend 240 is a multi-function pro- cess monitor designed to improve process plant efficiency and safety. The mainframe will accept up to 100 channels expandable to 1 000 channels with satellite units. Up to 32 functions and four alarm setpoints per channel are selected by Teletype or VDU Keyboard. The complete programme can be entered via the keyboard or automatically from punched tape.Scanning intervals are from 1 s to 24 h. Alarm scanning can be continuous with pro- grammable alarm delays. The unit will handle signals from all conventional process sensors for temperature, pressure, etc., and accommo- date remote scanning up to 300 f t . Lee Engineering Ltd., Napier House, Bridge Street, Walton on Thames, Surrey, KT12 1AP.Digital Indicators for Strain Gauge Trans - ducers The Model 420 Digital Indicator manufactured by Doric Scientific S.A. is an instrument for displaying in engineering units the equivalent output from strain gauge devices. This unit is self-contained and can be used to measure pressure, torque, thrust, force, mass, etc., with a resolution of 1 part in 10 000. The sensitivity is adjustable from 1 to 12 mV count-1.A clear display is pro- vided by five 0.63-in LEDs. Lee Engineering Ltd., Napier House, Bridge Street, Walton on Thames, Surrey, KT12 1AP. Microvolt Digital Voltmeter Doric Scientific S.A.’s model DS-100 digital voltmeter is claimed to give 1-pV resolution with 1-pV repeatability. The instrument has automatic zero correc- tions twice per second, a stability over 1 year of 0.03% of reading, computer compatible isolated outputs a t 20 readings per second and a guarded differential input giving 120dB CMR to all frequencies.Lee Engineering Ltd., Napier House, Bridge Street, Walton on Thames, Surrey, KT12 1AP. Non-contact Conveyor Belt Scale Kay-Ray have introduced a non-contact (nuclear) belt scale that will reliably and152 EQUIPMENT NEWS PYOC.Artalyt. Div. Chem. SOC. continuously measure the mass of material passing along a conveyor belt or feeder. The nucleonic belt scale requires much less maintenance than conventional electromechani- cal scales as there are no moving parts and there is no contact with the belt or idlers. In addition, the nucleonic scale is not affected by wind, temperature or tension and can easily be installed on short, inclined, enclosed, reversing or vibrating conveyors.Checking the calibration of the gauge requires only minutes in order to zero the gauge on one revolution of an empty belt and then check the span with a reference absorber plate established during initial calibration. Basic output is a voltage or milliampere signal equivalent to full-scale range in tons per hour.Optional modules and counter can be supplied to give an additional read-out in total tons over any period of time. When the belt speed is not constant, a tachometer is used to correct the basic mass flow signal. The accuracy of the system is approximately & 1% depending upon consistency of product and profile. The ion chamber detector is unaffected by vibration or shock and the detector assembly does not contain a signal pre-amplifier.The “A” Frame assembly can be installed around an existing belt and the remote electronics cabinet is watertight to NEMA 4 specifications. Industrial Instruments Division , Auriema Ltd., 442 Bath Road, Slough, SL1 6BB. Spectrophotometer The Hunterlab D54P-5 spectrophotometer incorporates a microcomputer processor.The processor consists of a pre-program- med microcomputer system that provides automatic standardisation and a correction factor for the contribution of the sample to the sphere wall. Spectrophotometric data for any of the four standard CIE illuminants A, C, D65 and F (cool white fluorescent) can be converted into a wide range of colour spaces, colour differences and specific indices of colour such as yellowness index, whiteness index and a special index of metamerism.Data can be printed out at 10- or 20-nm intervals from 400 to 710 nm or can be plotted as spectro curves on an optical curve plotter. BOC Automation, 2 Morris Way, Royal Oak Industrial Estate, Daventry, Northants. , NNll 5PB. Colour Control System The ACS (Applied Color Systems) 500 colour control system features the latest DEC com- puter equipment interfaced with automatic spectrophotometers such as the new ACS Spectra-sensor.The modular system includes a package of computer processor, mass storage, console terminal, spectrophotometer and interface, and computer software including the ACS CHROMA-PAC library of programs for colour laboratory and production applications. The ACS 500 system will create initial colour matches and can be used to evaluate substitute raw materials and new product formulations, and for quality control.BOC Automation, 2 Morris Way, Royal Oak Industrial Estate, Daventry, Northants. , NNll 5PB. Chloride Meter The Chloride Meter number 6610 is for simple chloride determinations with no sample prepara- tion.The instrument measures coulometrically with electronic end-point determination. Sample volumes of only 50 p1 of serum can be used and 100 tests can be made in one beaker of titrant. It has an operating time of 20 s for 100 mequiv 1-1 of chloride and titration starts automatically when sample is added. The colour-coded control lamps indicate instrument functions and there is a 4-digit display that shows the chloride concentration directly in milliequivalents per litre.No tools are required for the exchange of the electrode. A printer can be connected with the automatic printout of sample number and concentration. Anderman & Company Ltd., Central Avenue, East Molesey, Surrey. It is marketed by Eppendorf. Portable Viscometer The Viscotester 181/24 models made by Haake are for use in a wide variety of applications, hand held or in a bench stand.As the two-speed Viscotesters 181/24 can use the absolute range of stainless-steel viscosity sensors of the Rotovisco, they can give meaning- ful measurements even on non-Newtonian materials and, with the frequency converter FW, flow curves with up to six different shear rates can be plotted.Also there is a range of special “relative viscosity” attachments for quick “dip and read” measurements for batch checking and quality-control purposes. MSE Scientific Instruments, Manor Royal, Crawley, Sussex.June, 1977 EQUIPMENT NEWS 153 Double- beam Spectrophotometer The Cecil CE 505 double-beam unified spectro- photometer system for manual or automatic scanning of wavelengths is announced.The two basic spectrophotometers have wavelength ranges of 200-700 or 200-800 nm. Wavelength accuracy and reproducibility are better than 1 and h0.25 nm, respectively. Absorbance, concentration and transmittance are presented as a linear meter read-out and the absorbance scale can be expanded by up to 20 times, from 0-2 to 0.1 units f.s.d.Auto- matic changeover between the deuterium and tungsten filament light sources is included with manual changeover as an optional addition. The design of the large sample compartment allows the use of a large number of different cells and accessories. Digital read-out is available on the Model CE 595. For automatic scanning, the CE 500 control record module is required. Synchronised scans, either sequential or superimposed, scan speeds, wavelength scale expansion, scan lengths and fixed wavelength scan speeds can be varied to suit requirements.A. Gallenkamp & Co. Ltd., P.O. Box 290, Christopher Street, London, EC2P 2ER. Multichannel Analyser System The TN-1710 is a modular, LSI-11 micro- computer-based multichannel analyser system. The system is modular and the mainframe includes the microcomputer, a 6.5-in CRT display and 11 modular slots directly connected to the computer bus network.Data acquisi- tion modules are available for pulse-height analysis, signal averaging, optical spectroscopy, X-ray spectroscopy and multiple input scaling applications. Optional modules available in- clude a calibration module, an automatic sequencing module, a peak-ratio module, an optical transmission - absorbance module and a data-processing module.Versatile input - output capabilities include teletype X - Y recorder, EIA RS-232C, and floppy disk. Higher-level language is available for on-line interactive programming. Tracor Northern, Inc., 2551 West Beltline Highway, Middleton, Wisconsin 53562, USA. Automatic Peptide Protein Sequencer The APS24 Sequencer for the solid-phase sequential analysis of peptides and proteins is now available from Rank Hilger.The instru- ment was formerly produced by Anachem of Lu ton. An alternative version, the APS240 micro- sequencer, has just been produced. Operating on similar principles, it uses a radioactive reagent which increases the sensitivity of the technique.Rank Hilger, Westwood, Margate, Kent, CT9 4JL. Portable Water Deionisers The 24C and 48C portable deionisers are announced. The 48C Ionmiser produces up to 1 000 1 h-1 of ultrapure water, and the models are also designed to run in series or parallel, thus offering a far greater output. The models are compact, have low installation costs and are readily manoeuvrable on free-running castors.Permutit Standard Plant Division of House- man Hegro Ltd., The Priory, Burnham, Slough, SL1 7LS. Radioassay System The Prias systems for radioassay sample preparation and counting are introduced. Three independent benchtop instrument systems are available and together they form a complete, integrated radioassay system. The Sample Preparation System provides automated pipetting, dilution and aspiration of samples in preparation for radionuclide counting by the Automatic Gamma Counting System or the Liquid Scintillation Counting System.Touchtab keyboard entry for pro- gramming assays and integrated on-line data reduction are included. Packard Instrument Ltd., Caversham Bridge House, 13-1 7 Church Road, Caversham, Berks., RG4 7AA. Amino - acid Analyser with Computer The JlSO will complete a protein hydrolysate run in 45 min and is sufficiently sensitive to measure amino-acids present in amounts as small as 500pmol.A programming system is used to control the instrument's operation and can be quickly changed to suit different types of sample. The instrument requires only two buffer solutions and these in much smaller amounts than are normally necessary.Rank Hilger, Westwood, Margate, Kent, CT9 4JL. Direct-reading Spectrometer with Plasma Source, Glow Discharge and Argon Jet The E950 will automatically determine up to 36 elements at one time and present the results in printed form in less than 1 min. Full computer control is available to supervise all instrumental functions. The argon jet is a154 EQUIPMENT NEWS Proc.Analyt. Div. Gem. SOC. new sampling device and, together with the plasma source, glow discharge and conventional arc and spark excitation systems, allows the instrument to handle many different materials in both liquid and solid forms. Rank Hilger, Westwood, Margate, Kent, CT9 4JL. Electrode for the Measurement of Carbon Dioxide and Carbonate The carbon dioxide electrode recently intro- duced by Orion Research can be used for the measurement of carbon dioxide or carbonate in aqueous samples in the range 10-1 000 p.p.m.(as CaCO,) or for carbon dioxide up to 400 p.p.m. Higher concentrations can be read after sample dilution. Free carbon dioxide can be measured directly. Total carbonate (including hydrogen carbonate) is measured after adding an acid buffer to convert ionic forms to carbon dioxide. MSE Scientific Instruments, Manor Royal, Crawley, West Sussex, RHlO 2QQ. Reagent-cleaning System Many reagents can be cleaned until trace metal concentrations are as low as 5 x 10-lO~ by using the ESA Model 2014PM reagent-cleaning system.The system uses an electrochemical method of removing trace metals from reagents such as dilute acids, EDTA, buffers, and any reagents made of non-reducible salts.The reagents that are produced are suitable for atomic absorption, polarography, anodic stripping voltammetry and any other method in which ultrapure reagents are required. MSE Scientific Instruments, Manor Royal, Crawley, West Sussex, RHlO 2QQ. Hot-plates and Stirrers The Nuova 7 hot-plates from Sybron-Thermo- lyne bring top-plate temperature to 371 "C in 8 min.A demand-type thermostatic control responds to surface-area temperature changes with automatic compensation for ambient temperature or voltage fluctuations. The OV 10600 hot-plate oven is a small utility oven for low-temperature work, offering drying, baking, pre-heating and curing for many functions in industrial, clinical or school laboratories.At 100 O C , the temperature at any point in the chamber can be maintained within 3 OC. The maximum operating tempera- ture is 371 "C. Thermolyne's 2200 hot-plates (up to 12 x 24in top-plates) are useful for larger heating jobs or multiple smaller operations. Thermo- lyne 2600 comprises strong stainless-steel hous- ing constructed in two sections separated by thick insulation.This directs the heat up- wards and the controller section is kept cool and bench tops are protected from scorching. Clandon Scientific Ltd., Lysons Avenue, Ash Vale, Aldershot, Hants., GU12 5QF. MLW Thermostat Baths and Cryostats A selection of laboratory equipment made in East Germany is introduced. Module DKE is the temperature-regulating unit, comprising a thermostat with a single-stage pressure pump, module DSKE incorporates a double pump to aid suction and module KRE is the same unit with a stirrer in place of a pump.Combining these modules with the thermostat baths and ancillaries available in the same range permits assembly of units with capacities ranging from 2.5 to 15 1, as well as bridge immersion and suspension thermostats.All three thermostat units cover a temperature range from -60 to 260 "C. Control of the bath level is without movable parts and the location of the heater below the level control ensures that the heated area is always surrounded by liquid. The heating element is electronically controlled by Triac relay. The pump shaft bearing is located out- side the bath. For temperature control in cooling and refrigera- tion a range of equipment is available that includes uncontrolled cooling baths and also Ultra-Kryostats, developed chiefly for low- temperature work down to -180 "C.With the Ultra-Kryostat type N180 temperature control can be carried out either in an air bath or in a liquid bath. This is a modern low- temperature thermostat, with all-transistor control, in which the refrigerant is liquid nitrogen.Clandon Scientific Ltd., Lysons Avenue, Ash Vale, Aldershot, Hants., GU12 5QF. Cephalosporinase This enzyme is suitable for use as an analytical tool for the quantification of Cephalosporin C. Miles Laboratories' preparations are from an Ertterobacter species. The cells are disrupted by ultrasonication and cleared of cell debris by high-speed centrifugation.The resulting super- natant has a minimum specific activity of 1000 U ml-l.June, 1977 EQUIPMENT NEWS 155 Miles Laboratories Ltd., P.O. Box 37, Stoke Poges, Slough, SL2 4LY. Lectin Products Phytohaemagglutinin (PHA) is available as a Fartially- purified extract that will agglutinate all types of human, rabbit, dog, cat, mouse, sheep and guinea-pig erythrocytes.It also has the ability to initiate mitoses for chromosome analysis and lymphocyte kinetics. It is pre- pared from red kidney beans (Phaseolus vulgaris) by the method of Rigas and Osgood, and is available as a sterile freeze-dried powder, stable for 1 year at 4 "C. Peanut agglutinin (PNA) is a purified homo- geneous protein extracted from peanuts. It has a relative molecular mass of 110 000 and is a tetramer composed of four sub-units.The lectin will agglutinate neuraminidase-treated erythrocytes of all human ABO types. It will also agglutinate neuraminidase-treated lympho- cytes from mouse, rat, guinea-pig and man. However, it stimulates only treated rat and human cells. The lectin binds to galactosyl sites and galactose specifically inhibits agglutination and stimulation.Peanut extracts give the same immunological reaction as anti-T antibody and can therefore be used for the clinical deter- mination of T-polyagglutinability. The lectin is prepared from Arachis hypogaea by a modifi- cation of the method of Lotan et al. It is available as a saline solution and is stable for one year at -20 "C. The range of concanavalin-A products has been extended by the addition of the nickel- labelled product concanavalin A-G3Ni.Miles Laboratories Ltd., P.O. Box 37, Stoke Poges, Slough, SL2 4LY. Materials for Antibody Studies For fluorescence microscopy, fluorescein iso- thiocyanate is available at a purity exceeding 98 yo. For enzyme-labelling techniques, both horseradish peroxidase and alkaline phosphatase are offered in purified form.The needs of the electron microscopist are met with the three grades of cadmium-defined ferritin and also cationised ferritin. Miles Laboratories Ltd., P.O. Box 37, Stoke Poges, Slough, SL2 4LY. Antisera A number of antisera for radioimmunoassay are announced. These include a more specific material against aldosterone 3-BSA to replace the earlier aldosterone 17-BSA.Other new materials are an antiserum against digitoxin- BSA and compound S ( 17a-hydroxy- 1 1-deoxy- corticosterone), Both are produced in rabbit and are available in standard packs for 100- 5 000 tests. Miles Laboratories Ltd., P.O. Box 37, Stoke Poges, Slough, SL2 4LY. Human Antisera New human antisera include antibody to human myoglobin, /32 microglobulin and human IgA secretory component.The IgA antiserum reacts strongly with human milk and free secretory component, weakly with human secretory IgA and not a t all with normal human serum or serum IgA. The rabbit anti-myoglobin serum is specific for human myoglobin and does not cross-react with haemoglobin. The anti-human /32 microglobulin will be of particular use both in routine diagnostic work on Wilson's disease and cadmium poisoning and in the immunology of lymphocyte surface antigens of HL-A system.Miles Laboratories Ltd., P.O. Box 37, Stoke Poges, Slough, SL2 4LY. Standard for Lead Determination A new Ultrex standard for the evaluation of analytical methods for the determination of trace amounts of lead is available. The new standard, Baker Product No.4959, is a polymer rod containing lead at the 100 p.p.m. level. The rod can be cut into lengths corresponding to specific amounts of lead and each section can then be subjected to usual test methods. By using this standard the recovery and reliability of an analytical procedure can be established. The total lead content for each lot of rod standards is determined by atomic-absorption spectrometry and differential pulse polaro- J.T. Baker Chemicals B.V., P.O. Box 1, graphye Deventer, Holland. BHP - Activated Dextran 70 BHP - Activated Dextran 70 reacts spontane- ously with ligands (drugs, hormones, vitamins, enzymes, etc.) containing amino, thiol or hydroxyl groups. Thus the effective relative molecular mass of active substances can be increased by attachment to the soluble inert polymer while the activity of the ligand is retained.This will be useful for improvement156 FOURTH SAC CONFERENCE Proc. Analyt. Div. Chem. Soc. of in vivo localisation of pharmacologically active substances, for enhancing enzyme stability and for derivatising cofactors for re-use in enzyme electrodes and reaktors, etc. Pharmacia (Great Britain) Ltd., Paramount House, 75 Uxbridge Road, London, W5 5SS.Sephadex LH-60 Sephadex LH-60 extends the range of gels for adsorption/partition chromatography. The product complements Sephadex LH-20 and is used for gel filtration in organic solvents of higher relative molecular masses and the more lipid-soluble substances such as protected peptides. Pharmacia (Great Britain) Ltd., Paramount House, 75 Uxbridge Road, London, W5 5SS.Literature The February, 1977, issue of Infrared News, published by Wilks Scientific, features the Model 80 single-beam infrared spectrophoto- meter with a microcomputer. The newsletter also contains an article on eliminating cell and dilution errors in quantitative infrared analysis, and information on the use of the MIRAN-1 GPC/LC detector in new applications in liquid chromatography.Also available is a note recording changes made in maximum allowable exposures for various gases and vapours as proposed by NIOSH (the US National Institute for Occupational Safety and Health). Wilks Scientific Corporation, P.O. Box 449, S. Norwalk, Conn. 06856 USA. A report of work on the analysis of refinery gases by using only one gas chromatograph is available.Techmation Ltd., 58 Edgware Way, Edgware, Middx., HA8 8JP. A 28-page booklet from MSE Scientific Instru- ments describes the method used and apparatus required to measure the lead content of food cans by anodic stripping voltammetry. MSE Scientific Instruments, Manor Royal, Crawley, West Sussex, RH10 2QQ. Mettler News, in English, describes the PL fully electronic balances, the latest additions to the range. A brochure on the PT, PR and PS electronic precision balances has also been published. A. Gallenkamp & Co. Ltd., P.O. Box 290, Technic0 House, Christopher Street, London, EC2 2ER, or Mettler Instrumente AG, CH-8606 Greifensee-Zurich, Switzerland. The subject of a new leaflet from Siemens is total-hydrocarbon measuring equipment, based on their “Fidamat” range. Siemens Ltd., Great West House, Great West Road, Brentford, Middx., TW8 9DG. New application notes are available from Hewlett-Packard dealing with sample-prepara- tion methods for volatile organic compounds in water followed by automatic gas-chromato- graphic analysis (note ANGC 5-76). The use in this context of a capillary column inlet system is the subject of note ANGC 6-76. Another note, ANGC 8-76, describes how, with proper selection of gas chromatograph, nitrogen detector and column, the stringent standards set by the Food and Drug Administration for acrylonitrile in foods can be met. Hewlett-Packard Ltd., King Street Lane, Winnersh, Wokingham, Berks., RG11 5AR.

ISSN:0306-1396    

DOI:10.1039/AD9771400151

出版商:RSC    

年代:1977

数据来源: RSC

摘要:

156 FOURTH SAC CONFERENCE Proc. Analyt. Div. Chem. Soc. Fourth SAC Conference July 17-22, 1977, Birmingham Exhibition A comprehensive exhibition of laboratory apparatus and equipment has been organised and is to be held in the Chemical Laboratories of the Haworth Building (Nos. 204, 302 and 402) at the University of Birmingham. The Exhibition will be open at the following times : Monday July 18, 12.00-17.30 Tuesday July 19, 9.15-17.30 Wednesday July 20, 9.15-17.30 Thursday July 21, 9.15-17.30 In addition to displays of the latest scientific equipment from the major UK suppliers there will be several publishers’ stands, which will enable scientists to peruse the latest publica- tions in analytical chemistry.The following is a list of the Exhibitors. Applied Chromatography Systems Ltd.Academic Press Inc. (London) Ltd. Anachem Ltd. Anacon (Instruments) Ltd. BMAC Ltd. (Microanalysis) BDH Chemicals Ltd. Blackwell Scientific Publications Ltd. Baird Atomic Ltd. Cecil Instruments Ltd. Chemical Society Climpex Ltd. Coulter Electronics Ltd. Du Pont (UK) Ltd. EDT Research ElsevierJune, 19 77 NEW BS SPECIFICATIONS FOR THERMOMETERS EM1 Electron Tube Division Erba Science Fisons Scientific Apparatus Frost Instruments Ltd.Graphic Controls Ltd. Gilford Instruments Ltd. Grant Instruments (Cambridge) Ltd. A. Gallenkamp Ltd. Gelman Hawksley Ltd. Hopkin & Williams Ltd. Hewlett-Packard Ltd. Horwood - Wiley (Publishers) Instrumentation Laboratory (UK) Ltd. Koch-Light Laboratories Ltd. Life Science Laboratories Link Systems Malvern Instruments Ltd.MSE Scientific Instruments Pye Unicam Ltd. Perkin-Elmer Ltd. Panax Equipment Ltd. D. Reidel Publishing Co. Rooney & Ward Ltd. Roth Scientific Company Sartorius Scientific Co. Ltd. Searle Diagnostic Stanton Redcroft Scientific Glass Engineering (UK) Ltd. Spectra-Physics Ltd. Stuart Scientific Co. Ltd. Tecator Ltd. Technicon Telsec Instruments Ltd. Varian UKCIS Watson - Marlow Ltd. Waters Associates Ltd. Wilks Scientific Ltd. Whatman Lab Sales Ltd. 157 Further information can be obtained from Mr. J. Tillman, Research and Development Laboratories, Fisons Ltd., Pharmaceutical Divi- sion, Bakewell Road, Loughborough, Leicester- shire, LEll OQY.

ISSN:0306-1396    

DOI:10.1039/AD9771400156

出版商:RSC    

年代:1977

数据来源: RSC

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Jane, 1977 NEW BS SPECIFICATIONS FOR THERMOMETERS 157 New APA President At the Annual General Meeting of the Associ- ation of Public Analysts held a t York on April 23rd, 1977, Dr. Lewis Coles was invested as National President of the Association. Dr. Coles was Chairman of the South Wales Section of the Society for Analytical Chemistry in 1967 and has been an active member of the Society for many years. He is a member of the Analytical Methods Committee and Chair- man of the Metallic Impurities in Organic Matter Sub-committee of the AMC. Dr. Coles became a Public Analyst in 1961 and is now County Analyst to Mid and West Glamorgan. Dr. L. C o l a

ISSN:0306-1396    

DOI:10.1039/AD977140157b

出版商:RSC    

年代:1977

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158 CONFERENCES AND MEETINGS Proc. Analyt. Div. Chem. Soc. Courses Modern Techniques of Centrifugation September 12-17, 1977, Essex This 6-day course is to be held at the University of Essex and will cover all aspects of centri- f ugation. Primarily intended for postdoctoral workers, the course has been specially designed to give flexibility so that the inexperienced can also benefit. Registration forms must be returned by June 30th and can be obtained from Dr.D. Rickwood, Department of Biology, University of Essex, Wivenhoe Park, Colchester.June, 1977 PUBLICATIONS RECEIVED Identification of Small Particles September 19-23, 1977, London A specialised practical course in morphological analysis for those interested in air and water pollution, criminalistics, contamination analysis, clean room monitoring, etc., will be held at the Institute of Archaeology, Gordon Square.Topics covered include collection methods for micro- scopic sample preparation methods, sample handling and the manipulation of single small particles, characterisation procedures, crystallo- graphy, identification of single particles and, briefly, X-ray diffraction, electron microscopy and electron-microprobe analyses. Those interested should apply to The Reg- istrar, McCrone Research Institute, 2 McCrone Mews, Belsize Lane, London, NW3 5BG. 159

ISSN:0306-1396    

DOI:10.1039/AD977140158b

出版商:RSC    

年代:1977

数据来源: RSC

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June, 1977 PUBLICATIONS RECEIVED 159 Publications Received Bentley’s Textbook of Pharmaceutics. Eighth Edition. Edited by E. A. Rawlins. Pp. x + 725. London : Baillikre Tindall. 1977. Price kl2.50 Isoelectric Focusing. Edited by Nicholas Catsimpoolas. Pp. xii + 265. New York, San Francisco and London: Academic Press. 1976. Price fI16.70; $23.50. Aldehydes-Photometric Analysis. Vol- ume 4.Aldehyde Precursors : Formation and Analysis of Aldehydes (Part 11). Eugene Sawicki and Carole R. Sawicki. Pp. xiv + 285. London, New York and San Francisco : Academic Press. 1976, Price k12 ; $26.25. Fourier Transform NMR Techniques : A Practical Approach. K. Mullen and P. S. Pregosin. Pp. x + 149. London, New York and San Francisco: Aca- demic Press. 1976. Price L6.80; $14.75.Methods of Seawater Analysis. Klaus Grasshoff. Pp. xvi + 317. Weinheim and New York: Verlag Chemie. 1976. Price DM98. Clinical Pharmacy and Clinical Pharma- Edited by William A. Gouveia, Gianni Tognoni and Eppo van der Kleijn. Proceedings of a n International Symposium held in Boston, Mass. , USA, September 17-19, 1975. Pp. xviii + 463. Amsterdam, New York and Oxford: North- Holland.1976. Price $55.50; Dfl136. cology. Colorimetric and Fluorimetric Analysis of Steroids. J. Bartos and M. Pesez. Pp. xii + 274. London, New York and San Francisco : Academic Press. 1976. Price k9.80; $21.50. The Analysis of Rocket Propellants. Hugh E. Malone. Pp. x + 148. London, New York and San Francisco: Academic Press. 1976. Price k6.50; $14.25. Absorption Spectra in the Infrared Region.Volume 3. Edited by L. LAng. Pp. 320. Budapest: Akadkmiai Kiad6. 1977. Price Ll8. Absorption Spectra in the Ultraviolet and Visible Region. Volume XXI. Edited by L. LAng. Pp. 423. Budapest: Akadkmiai Kiad6. 1977. Price L22. Conservation of Resources. A Symposium Held at The University of Glasgow, 5th-9th April, 1976. Pp. x + 245. Special Publication No. 27. London : The Chemical Society.1977. Price k6; $12 (CS members L3). Electrothermal Atomization for Atomic Absorption Spectrometry. C. W. Fuller. Analytical Sciences Monographs, No. 4. Pp. viii + 127. London: The Chemical Society. Treatise on Analytical Chemistry. Part 111. Analytical Chemistry in Industry. Volume 3. Edited by I. M. Koltoff, Philip J . Elving and Fred H. Stross. Pp. xxiv + 598.New York, London, Sydney and Toronto: John Wiley. 1976. Price k27.70; $46.95. Die Chemische Industrie und ihre Helfer, Ausgabe 1976/77. Pp. 600. Darmstadt : Industrieschau-Verlags- gesellschaft mbH. Price DM38. Gas Chromatographic Headspace Analysis. Horst Hachenberg and Adolf P. Schmidt. Translated by D. Verdin. Pp. xiv + 125. London, New York and Rheine: Heyden. 1977. Price fT9.50; $19; DM61.Liquid Scintillation Counting. Volume 4. Edited by M. A. Crook and P. Johnson. Pro- ceedings of a Symposium on Liquid Scintillation Counting organised by the Radiochemical Methods Group (Analytical Division, The Chemical Society), Bath, England, September 16-19, 1975. Pp. x + 269. London, New York and Rheine: Heyden. 1977. Price k16; $32; DM102.50. Price f16.75 (CS members k5).160 PUBLICATIONS RECEIVED PYOC.Analyt. Div. Chem. SOC. Bibliography of Liquid Column Chromato- graphy 1971-1973 and Survey of Applica- tions. ZdenEk Deyl and Jan Kopecky. Supplementary Volume No. 6, 1976, to the Journal of Chromato- graphy. Pp. xx + 1135. Amsterdam, Oxford and New York: Elsevier. 1976. Price $103.50; Dfl259: subscription price $61.25; Dfl150.Wilson and Wilson’s Comprehensive Analy- tical Chemistry. Volume VIII. Enzyme Electrodes in Analytical Chemistry, Mole- cular Fluorescence Spectroscopy, Photo- metric Titrations, Analytical Applications of Interferometry. Edited by G. Svehla. Pp. xvi + 589. Amster- dam, Oxford and New York: Elsevier. 1977. Price $77.75; Dfl190: subscription price $65.75; Dfl161. Analytical Biochemistry of Insects.Edited by Ralph B. Turner. Pp. viii + 315. Amsterdam, Oxford and New York: Elsevier. 1977. Price $30.25; Dfl74. Vibrational Spectra of Organometallic Compounds. Edward Maslowsky, Jr. Pp. xiv + 528. New York, London, Sydney and Toronto : John Wiley. 1977. Price L18.75; $31.70. Flameless Atomic Absorption Analysis : An Update. A Symposium Presented at the-Seventy-eighth Annual Meeting, Ameri- can Society for Testing and Materials, Montreal, Canada, 22-27 June, 1975.A S T M Special Technical Publication 618. Pp. viii + 64. Philadelphia: American Society for Testing and Materials. 1977. Price $7. Final Report on. Interlaboratory Cooper- ative Study of the Precision and Accuracy of the Determination of Sulfur Oxides in Gaseous Combustion Products (Barium Chloranilate Method) Using ASTM Method J.E. Howes, Jr., R. N. Pesut and J. F. Foster. A S T M Data Series Publication 55-S9. Pp. viii + 102. Philadelphia : American Society for Testing and Materials. 1976. Price $12. D 3226-73T. Fluorescence and Phosphorescence Spec- troscopy : Physicochemical Principles and Practice. Stephen G. Schulman. International Series in Analytical chemistry, Volume 59.Pp. x f 288. Oxford, New York, Toronto, Sydney, Paris and Frankfurt : Pergamon Press. 1977. Price i l l ; $20. Biological Monitoring of Water and Effluent Quality. A Symposium Sponsored by ASTM Committee D-19 on Water, American Society for Testing and Materials, Blacks- burg, Va., 2 4 Nov. 1975. Edited by John Cairns, Jr., K. L. Dickson and G. F. Westlake.A S T M Special Technical PzcbZicatioPz 607. Pp. viii + 246. Philadel- phia : American Society for Testing and Materials. 1977. Price $24.25. Thermal Analysis of Minerals. Dumitru N. Todor. Pp. 256. Tunbridge Wells : Abacus Press. 1976. Price L12.50. Reaction Mechanisms in Organic Chem- istry. Florin Badea. Pp. 701. Tunbridge Wells: Abacus Press. 1977. Price k18.85. IARC Monographs on the Evaluation of Carcinogenic Risk of Chemicals to Man.Volume 12. Some Carbamates, Thio- carbamates and Carbazides. Pp. 282. Lyon: International Agency for Research on Cancer. Distributed by the World Health Organization. Available in the UK through HM Stationery Office, London. 1976. Price SwFr34; $14. Environmental Pollution and Carcino- genic Risks: Proceedings of a Symposium organised by IARC and the French National Institute of Health and Medical Research, held in Lyon, France, 3-5 November, 1975.Edited by C. Rosenfeld and W. Davis. I A R C Scientific Publications, Number 13. Inserm Symposium Series, Volume 52. Pp. 476. Lyon : International Agency for Research on Cancer. Distributed by the World Health Organisation. Available in the UK through HM Stationery Office, London. 1976. Price SwFr50; $20. Environmental N- Nitroso Compounds- Analysis and Formation. Proceedings of the Fourth Working Conference held in Tallinn, Estonian SSR, 1-3 October, 1975. Edited by E. A. Walker, P. Bogovski and L. Griciute. I A RC Scientipc Publications, Number 14. Pp. xviii + 512. Lyon: International Agency for Research on Cancer. Distributed by the World Health Organization. Available in the UK through HM Stationery Office, London. 1976. Price SwFr110; $45. Chemistry of Marine Sediments. Edited by T. F. Yen. Pp. vi + 265. Ann Arbor, Mich. : Ann Arbor Science Publishers. 1977. Price L13.40; $22.

ISSN:0306-1396    

DOI:10.1039/AD9771400159

出版商:RSC    

年代:1977

数据来源: RSC