ISSN:0144-557X    

DOI:10.1039/AP98522FX037

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

... 111 The Meeting of the Automatic Methods Group on "Automated Analysis in Support of Biotechnology" will not now be held on December 5th at UMlST but will be combined with the Divisional Meeting (jointly organised with the East of England Region of the Industrial Division) being held at New Hall, Cambridge, on Thursday, December 12th. The title of the combined meeting will be "Biotechnology-Analytical Techniques and Au tom at i o n . " The AGM of the Automatic Methods Group will now be held at 2.00 p.m. at New Hall, Cambridge, on Thursday, December 12th.

ISSN:0144-557X    

DOI:10.1039/AP98522BX039

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 285 Ed itoria I This Editorial has been contributed by Dr. H. J. Cluley who, apart from being a former Chairman of the Analyst Publications Committee (forerunner of the Analytical Editorial Board), is a member of the NATLAS Chemical Technical Committee and also represents the RSC on that Committee. From NATLAS to NAMAS The National Laboratory Accreditation Scheme (NATLAS) formally came into existence on October 22nd, 1981. As the scheme has run for 4 years and is now being incorporated into a new organisa- tion, NAMAS, as explained later, the present seems an appropriate time to report on the development of the scheme to date. The over-all objective was to have under NATLAS a single, unified labora- tory accreditation scheme for the United Kingdom.In particular, the aims were to eliminate the multiple assessment of lab- oratories, as could occur from the pre- vious existence of several accreditation schemes, to secure overseas recognition of tests undertaken in UK laboratories and to improve the standard of testing in UK laboratories and thereby enhance the quality and reputation of British goods. The scheme has been administered by the NATLAS Executive, a unit of the National Physical Laboratory at Tedding- ton. The Executive is guided by the NATLAS Steering Committee and receives advice from five technical com- mittees and working groups concerned with chemical, electrical, mechanical, physical and construction industry test- ing. In the formative stage, NATLAS was subsidised by the Department of Industry, but was later required to be self supporting.This requirement is fulfilled by means of fees paid by laboratories for initial assessment on requesting accredita- tion, and by the annual fees paid by laboratories gaining accreditation. NATLAS was given a good start in 1981 by the agreement of various organi- sations (including such diverse bodies as British Ready Mixed Concrete Associa- tion, British Standards Institution, Cen- tral Electricity Generating Board and Ministry of Defence) to cease their indi- vidual accreditation schemes in favour of the NATLAS scheme. This provided an initial nucleus of about a hundred labora- tories, previously accredited under the schemes being superseded, and which were given immediate, but provisional, NATLAS accreditation. These labora- tories are being progressively re-assessed to ensure that their accreditation (where renewed) is put on a firmer basis and conforms to the principles that NATLAS has formulated for laboratories seeking accreditation. Laboratories applying for the first time for accreditation have also required assessment.The present posi- tion is that 260 laboratories are currently accredited, 3 laboratories are suspended and a further 155 applications from lab- oratories are being processed. Of the 260 laboratories accredited, about 100 include chemical tests in their scope. The assessment of these many labora- tories with respect to .accreditation has been a major exercise. Continuing effort on laboratory appraisal is also required to fulfil the periodic surveillance visits that each accredited laboratory receives as a check on whether the standards deman- ded for accreditation are being main- tained.In addition, it is the intention of NATLAS to ensure that about every 4 years each accredited laboratory receives a major re-assessment to enable the accreditation to be renewed (if appro- priate) for a further period. This continu- ing need for assessment, re-assessment and surveillance of laboratories has neces- sitated the building up of a sizeable panel of suitably qualified laboratory assessors. Again, NATLAS has been able to profit from the various accreditation schemes previously in existence, which yielded a nucleus of experienced assessors, and this has been substantially supplemented by new assessors.Where appropriate, would-be assessors have attended specially designed training courses at the Portsmouth Management Centre. NATLAS currently has a panel of 135 active assessors, of whom about 40 are suitably qualified to appraise chemical laboratories. It should be emphasised that NATLAS aims to use an assessor to appraise only those laboratories with acti- vities corresponding to the area of the assessor’s special expertise; any labora- tory has the right to reject an assessor proposed by NATLAS. Laboratories are asked to specify the scope of the tests for which they seek accreditation, and these may be only a part of their total activities. Conversely, an assessor may decide that only a part of the activities specified by a laboratory merits accreditation.Laboratories seeking accreditation are provided by NATLAS with guidelines as to the criteria they need to fulfil in order to gain accreditation. Particular emphasis is laid on rigorously specified, written procedures for the tests for which accredi- tation is sought, the use of an internal quality control system to guard against erroneous results, and suitable trace- ability of any measurements or standards used in the tests or for quality control. It should be pointed out that whilst NATLAS is able, in principle, to accredit a laboratory for carrying out any objective test (provided that it is adequately documented), it is not able to accredit individuals for opinions based on the results of such tests. Hence, because interpretation of the exerimental findings is an essential feature of chemical and analytical work of an investigatory or consultative nature, such activities are deemed to be outside the scope of the NATLAS scheme.NATLAS policy on the traceability of measurements requires that any measure- ments be traceable where the concept is applicable, through an unbroken chain of calibrations, to UK standards of measure- ment. In chemical testing, this concept applies to items such as weights and balances, calibrated (volumetric) glass- ware, thermometers and test sieves. This policy on traceability of measurement has necessitated close co-operation between NATLAS and the British Calibration Service (BCS), which accredits labora- tories for the calibration of instruments and for the measurement of gauges and reference materials. Both NATLAS and BCS are managed by the National Physical Laboratory under the auspices of the Department of Industry. The logical step has now been taken of merging NATLAS and BCS into a single organisa- tion with effect from October lst, 1985. The new organisation will be known as the National Measurement Accreditation Service (NAMAS). However, the names of NATLAS and BCS are now so well known as to necessitate their retention to describe their respective areas of activity in the new organisation, NAMAS. H. J. CLULEY

ISSN:0144-557X    

DOI:10.1039/AP9852200285

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

286 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 Analytical Viewpoint ~~~~ ~ ~ ~ The following is the second in what is intended to be a continuing series of articles providing either a personal view of part of one discipline in analytical chemistry (its present state, where it may be leading, etc.), or a philosophical look at a topic of relevance t o chemists in general or analytical chemists in particular. These contributions need not have been the subject of papers at Analytical Division Meetings. Persons wishing to provide an article for publication in this series are invited to contact the Editor of Analytical Proceedings, who will be pleased t o receive manuscripts or t o discuss outline ideas with prospective authors. Multiple Element Standards in Ampoules for Atomic Absorption Spectrop hotometry John Theodore Gillingham British Columbia Institute of Technology, Burnab y, British Columbia, Canada It is rather surprising to realise that after about 25 years of work with atomic absorption spectrophotometry, stock standards for this purpose are still supplied commercially* as single element standards at a concentration of 1000 p.p.m.(pg ml-1) of element. A spectroscopy laboratory must, therefore, maintain a considerable inventory of stock standards, and the day to day work involves the maintenance of intermediate and working standards for each element, which can result in a large number of bottles. The author has prepared and used multiple element stan- dards in ampoules since the time of flame photometry, in order to reduce the volume of work with the alternative described above.Furthermore, as the elements occur together in the samples, it seems only logical that they should occur together in the standards. A number of elements can be grouped together into one standard to suit the analytical requirements of the laboratory. For example, sodium, potassium, calcium and magnesium can be incorporated into one standard, as is shown in Table 1. Table 1. A multiple element standard for sodium, potassium, calcium, and magnesium. Insoluble weighing forms, calcium carbonate and magnesium turnings are dissolved in 25 ml of concentrated hydro- chloric acid Weighing form Concentration/ (analytical-reagent grade) g 1-1 Cation/pg mIk1 NaCl 2.5421 loo0 KC1 1.9067 loo0 CaC03 2.4973 lo00 Mg turnings 1 .ow0 lo00 This multiple element standard was originally prepared and used by the author for the analysis of heparinised blood plasmas when the Beckman flame photometer first appeared in the laboratory (circa 1952).When atomic absorption spectro- photometers became available, the author then used this standard for the analysis of plant materials, food and soil extracts. The minor elements, copper, zinc, iron and manganese, can * J. T. Baker Chemical Co., Phillipsburg, New Jersey. likewise be incorporated into another standard, as is shown in Table 2, for the analysis of plant materials, food and soils. Table 2. A multiple element standard for copper, iron, manganese and zinc. These metals are dissolved in 50 ml of aqua regia [nitric acid - hydrochloric acid (1 + 3)].The reaction is vigorous and the acid is added from an offset burette Concentration/ Weighing form g 1-1 Cation/pg ml-1 Copper wire 99.5% 1 .oooo lo00 Iron wire 99.9% 1 .moo lo00 Manganese 99.0% 1 .oooo lo00 Zinc granules 99.0% 1 .m 1000 The preparation of standard solutions for this purpose, or indeed for any purpose, requires a good understanding of ideal weighing forms so that hygroscopic, deliquescent and efflores- cent salts can be avoided. Many of the elements can be obtained in the metallic form and virtually pure, and therefore this weighing form eliminates all uncertainties regarding water of crystallisation and the phenomena referred to above. Hence, the metallic form of copper, iron, magnesium, man- ganese and zinc, for example, is without question the best option available to the chemist.Other elements can also be obtained in metallic form. The dispensing of stock standards into ampoules is a very valuable technique and offers the chemist absolute relief from evaporation, contamination, precipitation reactions and microbiological growth, and the standards are preserved indefinitely. An ampoule can be opened each day to serve as the basis for the day’s work. This technique can be applied to preserving spectrophotometric standards as well, nitrate, nitrite and phosphorus being good examples. Ampoules can be purchased with a fused on annular ring that permits opening simply by snapping the neck off with the fingers, so that files are no longer needed. It is convenient to purchase 5 ml ampoules by the gross, and these can be quickly filled with an automatic dispensing syringe fitted with a 14 gauge cannula. While there are special ampoule sealing burners, an Amal burner and forceps will serve very well for this purpose. Finally, the ampoules can be sterilised in an autoclave.

ISSN:0144-557X    

DOI:10.1039/AP9852200286

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 287 Theophilus Redwood Lecture The fourteenth Analytical Division Theophilus Redwood Lecture was presented by Professor Dr. Manfred Grasserbauer at the RSC Annual Chemical Congress at the University of St. Andrews on March 26th, 1985. Surface Analysis for the Dev,elopment of Micro-electronic Devices M. Grasserbauer Institute for Analytical Chemistry, Technical University, Getreidemarkt 9, A- 1060 Wien, Austria Introduction The development and production of electronic equipment is one of the key of technology. The total yearly consump- tion in the three leading geographical areas, USA, Western Europe and Japan, was 286 000 million US$ in 1984.' feature size has decreased from 50 to 2-3 pm (Fig. 1). It is now approaching sub-micrometer dimensions in the 1 Mbit RAM.Vertical dimensions have been reduced in a similar manner; the gate oxide of an MOS (metal oxide silicon) transistor of 1950 was 200 nm, now it is in the range of 10-50 nm. This trend is characterised by the term VLSI (very large scale integra- tion). Fig. 1. SEM micrograph of surface of 256 kbit RAM showing the smallness of the structure of VLSI devices in comparison with a human hair (reproduced by courtesy of Siemens, Munich) Professor Dr. M . Grasserbauer The development of microelectronic devices plays a key role in the production and growth of electronic industry. Most microelectronic devices are based on silicon technology. The basic unit for integrated circuits is the transistor, which was invented 1947 in the Bell Laboratories by Bardeen, Brattain and Schockley,2*3 who were awarded the Nobel Prize in 1956 for this pioneering work.Today silicon is the most important material for high technology. According to Deal and Crossley4 the major trend in the evolution of semiconductors concerns the dramatic increase in complexity and density of solid state device structures; the number of components per circuit has increased from 1 in 1950 to over a quarter of a million [in today's 256 kbit RAMS (random access memories)]. The The major goals in development of new production tech- niques are miniaturisation and increase of production yield. Actual figures for the yields are secrets of the individual companies, but one can estimate that the production yield of a 64 kbit RAM is in the order of 40-50%, while that of the 256 kbit RAM is about 25%.Yields increase substantially with the duration of a production line. The yield of device production is given by physical or chemical defects on a chip. Thus, the study of the individual chemical and physical processes occurring in the semiconduc- tor during device production is one of the major tasks in research. Empirical knowledge and trial and error methods still play a key role in the development of improved or new production techniques. However, to an increasing extent mathematical -288 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 Table 1. Figures of merit for distribution analysis of the major dopant elements in silicon Method and Lateral Depth Detection limit/ element: reaction resolution/pm resolutiodnm atoms cm-3 RBS As 10-104 5-100 10‘8 Sb 10-104 5- 100 1017 B: lOB(n, a) 7Li - 10-50 10‘4 As: 75As(n, ~ ) ~ 6 A s - 10-50 1017 P: 31P(n, y)3*P P-decay - 10-50 1017 1°B, IlB 1-60 2-10 1014 P 1-60 2-10 1015 NAA Sb : 121Sb( n , y ) l22Sb - 10-50 5.1015 SIMS As 1-60 2-10 3.10’5 121Sb, 123Sb 1-60 2-10 3.10’5, 3.1014 Dynamic range 104 104 10’ 5.104 5.104 106 107 105 106 106 Accuracy, YO relative 10 10 1 10 10 10 10 10-20 2 w o 10-20 physical models for the processes occurring in semiconductor production are being developed.5-7 In order to establish such models extensive and accurate experimental work, including thorough analytical characterisation, has to be performed.In this area analysis is one of the keys for progress. Analytical chemistry is also of great significance in the characterisation of materials used for production (wafers, solutions, etc.) . Furthermore, physical high resolution tech- niques are very important in failure analysis for the character- isation of chemical and physical defects in devices. Surface Analysis for Development and Production of VLSI Devices Survey of Analytical Techniques The most important task in VLSI development is the charac- terisation of the dopant elements, because their type and distribution determine directly the electrical properties of a transistor.Also, as considerable progress has been achieved within the last few years emphasis is put on this topic, covering methodological developments and treatment of the most important problems for the development of VLSI devices.Methodological Aspects of Distribution Analysis of Dopant Elements The major goal of analysis is to characterise the distribution of the dopant elements in semiconductor devices. Owing to the small size of the structures used in silicon technology (about 0.1 to more than 10 vm) lateral distribution analysis and direct depth distribution analysis of such devices is very limited. The existing physical analytical techniques using focused particle beams often do not exhibit sufficient lateral resolution. As a consequence, in semiconductor research large scale samples (dimensions > 1 mm) are usually investigated. The individual steps of device production are carried out on these samples and the physical and chemical behaviour of the dopant elements is investigated.The accurate distribution analysis of the (total and electrically active) dopant elements serves as a basis for establishing mathematical - physical models, which describe the behaviour of these trace elements as a function of (production) process parameters (“process modelling”) .536 Such models can then be used to calculate the properties determining distribution in the small scale devices (reduction of lateral dimensions from millimetres to microns, depth scale remaining constant). This “transfer of information” enables the optimisation of device production, the study of physical processes in devices and the prediction of electrical device properties (“device modelling”) .7 The major requirements for surface (depth) distribution analysis in semiconductor materials are: separate determina- tion of electrically active and total elemental concentrations of boron, arsenic, phosphorus (and antimony) in silicon; large dynamic range of analysis and high detection power (concen- tration range about 1014-5 x 1021 atoms cm-3); large spatial (depth) resolution ( X nm); and high accuracy of analytical information (concentration versus depth).Only a few analy- tical techniques fulfil these requirements to a large extent, even in the characterisation of large-scale samples. Methods for surface analysis of dopant elements8 Surface resistance measurements are mainly used for distribu- tion analysis of the electrically active fraction of the dopant elements. For elemental surface distribution analysis the major techniques are neutron activation analysis (NAA),9 secondary ion mass spectrometry (SIMS)10-14 and Rutherford back- scattering spectrometry (RBS). l 5 ~ 6 The key analytical features of each of these techniques are given in Table 1.The main advantage of NAA is its high accuracy; the major disadvan- tages are a low dynamic range, tedious surface etching procedures for phosphorus, arsenic and antimony and isotopic limitations (for boron only 1OB and for antimony only 121Sb can be determined). RBS is only useful for determining arsenic and antimony when there is a large mass difference between dopant and matrix elements. It offers high accuracy, but poorer depth resolution than NAA or SIMS. RBS provides unique structural information about dopant elements because, as a result of suitable alignment of the ion beam with respect to the silicon lattice, dopant atoms on interstitial sites can be distinguished from those on lattice sites.The major advantages of SIMS are a large dynamic range for surface distribution analysis, high detection power, excellent spatial (depth) resolution, the possibility of analysing all isotopes and a high speed of analysis. The accuracy of this technique is not as good as that of NAA, but it is sufficient for the very high demands of process modelling. These figures of merit (Table 1) are based on the use of sophisticated ion microprobe instruments (Cameca IMS 3f), which combine high standard microanalytical features with high-performance mass spectrometry (double focusing spec- trometers). Such figures of merit can only be obtained with a thorough understanding of the complex process of signal generation after methodological developments for maximum detection power and accuracy and the elimination of artefacts, especially those encountered in the characterisation of hetero- geneous structures (e.g., silica - silicon). ~ 7 ~ 8 Optimised measurement techniques have to be developed for each element. Quantitative distribution information is obtained by measurement of the crater depth and conversion of the secondary ion intensity in the depth profile into atomic concentrations by means of relative sensitivity factors (usually obtained by the integration method’*). For the assessment of accuracy SIMS is combined with NAA, RBS and electrical measurements.ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 Combination of analytical techniques for obtaining maximum information In order to gain maximum information about the distribution of the dopant elements SIMS, being the major technique at the present state, is frequently combined with electrical measure- ments, RBS and electron microscopy.The combination of SIMS with electrical measurements allows a separate determi- nation of the distribution of the total dopants (elemental analysis) and the electrically active fraction, which may be considerably lower at high dopant concentrations. Electrical measurements can only be used after annealing because the implanted ions are inactive owing to structural disorder. Fig. 2 shows the depth profiles of total and active antimony in an annealed sample. SIMS and RBS allow one to combine elemental distribution with structural information (for anti- mony and arsenic).RBS in random alignment of the He+ beam yields spectra that are produced by collisions with all target particles within the accessible surface zone irrespective of their structural positions. In channelling alignment only atoms at interstitial lattice positions contribute to back-scattering. Antimony Solubility limit I 1017 \ of Sb in Si 10’6 ’ I 1 I 0 0.10 0.20 0.30 0.40 Depth/pm Fig. 2. Depth profiles of Sb in Si (80 keV, 3 X 1015 cm-2; annealing: 1000°C, 60 min, N2). Solid line, SIMS measurement yielding distri- bution of elemental Sb; broken line, surface resistance measurement yielding distribution of electrically active Sb Fig. 3 shows as an example the RBS spectra of an annealed antimony sample.Roughly 80% of the antimony atoms are positioned on interstitial sites and are therefore electrically inactive. The silicon spectrum obtained in the channelling mode shows the rest damage after the annealing step. The extension of this analytical system by electron micro- scopy allows the analyst to obtain additional distribution information when precipitations occur. Morphology, chemical composition and distribution of precipitations can be studied with transmission electron microscopy (TEM) down to a size of about 5 nm. Fig. 4 shows precipitations of antimony in silicon. TEM yields information on physical defects, such as dislocations, stacking faults and point defect agglomerates, which have a pronounced influence on dopant redistribution during the production of a device.20 Analytical Problems and Results The production of microelectronic devices consists of a number of basic processes, which are combined and repeated in a specific manner for a certain type of device.These basic operations are oxidation, lithography (resist deposition, expo- sure, development), etching, epitaxy, thin-film deposition, ion implantation and diffusion. These operations for the produc- tion of a metal oxide silicon (MOS) device (DRAM) have been described by, for example, Brodie and Muray.21 3000 .g 200c C 5 B - 1000 0 Silicon i I00 150 200 289 300 1 I 0 250 260 270 280- 290 Channel number Fig. 3. RBS spectra of Sb in Si after annealing (80 keV, 3 X lot5 cm-2; annealing: 1000°C, 60 min, N2).Crosses, random orientation between Si lattice and ion beam . Si or Sb on lattice and interstitial sites contribute to the back scattering signal. Open circles, ion beam orientated towards Si lattice in <loo> direction. Only Si or Sb atoms at interstitial sites contribute to the back scattering signal. (RBS measurements b y W. K. Chu, Chapel Hill) The following processes and parameters are of particular significance because they influence the electrical properties of a device directly: ion implantation (type of ion, energy, dose); diffusion during annealing and oxidation (temperature, time, atmosphere). Fig. 4. TEM micrograph showing precipitations of Sb at dislocations: implantation 200 keV, 4.4 x 1015 em-2; annealing, 550 “C, 20 min and 90O0C, 30 min (from Narajan and Holland’g) Ion implantation For process modelling the distribution of the dopant elements after ion implantation should be described with maximum accuracy. Generally, a Gaussian type distribution function with 4 moments (mean projected range, R , range distribution Rp, skewness and curtosis) is used (Pearson IV). These four parameters have to be determined empirically for a given system by accurate measurement of implantation profiles and application of fitting procedures. Systematic investigations of profiles for the various dopant elements as a function of energy and dose have to be performed.290 10'7 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 - p-Doping with boron.NAA and SIMS can be used for the experimental determination of the profile equally well.As implantation is performed through a silica layer the influence of the different stopping power22 in silica and silicon has to be included in the simulation. Fig. 5 compares the measured profile of implanted boron (25 nm silica, 25 keV, 1013 atoms cm-2) with the simulation of the implantation based on the Pearson IV distribution? The agreement between the experi- ment and the mathematical model is very good for concentra- tions of boron used in field and channel implantations. I &Si i 25 keV, 1013 cm-2, 25 nm Si02 I I I \ I \ I A1 I I 0 0.5 1 J I I Depth/pm Fig. 5. Comparison of measured (SIMS) and calculated implantation profile of B in Si (profile 1). Broken line, SIMS; open circles, SUPREM I1 n-Implantation with arsenic and phosphorus.The major technique for distribution analysis of these elements is SIMS, because NAA demands chemical etching. Implantations for source - drain areas are performed with high doses in order to generate a high carrier density, which is especially important for VLSI. Fig. 6 shows the measured (SIMS) and calculated (SUPREM 11) profiles of an arsenic implant through 50 nm silica (150 keV, 9 X 1015 atoms cm-2). Significant deviations between the measurements and simulation are encountered near to the As-+ Si 50 nm Si02 c L -0.05 0 0.1 0.2 0.3 Depthlpm Fig. 6. Comparison of measured and calculated implantation profile of As in Si. Closed circles, SIMS; broken line, SUPREM 11; crosses, NAA silica - silicon interface and in a depth larger than 200 nm. In the first instance the interaction of the arsenic ions with the silica layer, and in the second channelling effects, have not been considered adequately in the model.23 In high dose implantations artefacts can occur which are of significance for further processing.One of these effects is the recoil of oxygen atoms from silica into silicon due to momentum transfer from the implanted As+ ions. Fig. 7 shows the arsenic and oxygen profile for an implantation of arsenic through 45 nm silica (150 keV, 9 x 1015 atoms cm-2). A typical recoil profile of oxygen is found in the silicon.23.24 I As+Si I 1. X X X X I I I 0 0.1 0.2 0.3 Depth/pm Fig. 7. SIMS profile of As and 0 in 45 nm Si02/Si structure showing recoil implantation of 0 from SiOz due to the implantation of As through the oxide (150 keV, 9.1015 cm-2).Crosses, arsenic; closed circles, oxygen Diffusion Annealing. Annealing is performed in order to achieve recrystallisation of the silicon, structural reorganisation of the dopant atoms into substitutional positions and, consequently, electrical activation. The annealing technique that is currently used for device production is thermal heating, typically 1 h at 1000 "C, which causes strong diffusion effects of the dopant elements. It is specifically applied after source - drain implan- tation with arsenic or phosphorus. The modelling of the diffusion processes is very difficult for high concentrations, as encountered for source - drain areas in VLSI, because the diffusion coefficient is dependent on concentration in that instance.The diffusion mechanisms are not clearly established yet, but the participation of interstitials and vacancies is assumed .23 In a pragmatic approach for modelling the extrinsic diffusion coefficient ( D ) can be connected with the intrinsic diffusion coefficient (Q) by a series of multiplicative terms, which should express the various influences22: D = Di x d X dF X d, where d is the term for vacancy and interstitial enhancement, dF the term for field enhancement generated by the steep concentration gradient of the implantation profile, d, the term for cluster retarding and Ci CV d =fi X - + fv X - Ci* C"* where fi andf, are the contribution of interstitials and vacancies to diffusion, ci and c, the concentrations of interstitials and vacancies (in extrinsic state) and ci*,cv* the concentrations ofANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 291 interstitials and vacancies in intrinsic state (typically 1013- lOI7 ~ m - ~ for T = 800-1100°C); CilCi*, C,/C,* represent the supersaturation of interstitials and vacancies, typically 1-10.Just to show the difficulties associated with the mathematical calculation of redistributed profiles after annealing it can be mentioned that values differing by a factor of 50 for Di have been reported22 and that the factors d and d, can influence D by 2 orders of magnitude. Consequently, extensive systematic investigations must be carried out to determine the depend- ence of the diffusion coefficient on experimental and specimen parameters. A further aspect is that electrical activation at high dopant concentrations is incomplete when the "electrical solubility limit" for a dopant element in silicon is exceeded.Only the electrically active fraction of the dopant element determines the electrical properties, but diffusion is also (strongly) influenced by the inactive fraction. Fig. 8 shows, as an example, the redistribution of arsenic implanted into silicon through 50 nm silica (150 keV, 9 x 1015 cm-2) annealed under various conditions (profiles 2-5). It is evident from these SIMS profiles that profile broadening, typically by a factor of 2, occurs even for arsenic, although this element has a very low diffusion coefficient. The dependence of electrical solubility on annealing temper- ature is described by this expression: - E - 'A max. = 1.90 x 1022e k T cm-3 k= 8.6 x 10-5 eV K-1 where k is Boltzmann's constant and E is the energy of formation of the inactive arsenic clusters according to the reaction mAs+ + n e- As,,,(m--n) rn (lOOOnC) = 2 - 3 n = l A value of 0.453 eV for E has been determined.These arsenic clusters are positioned on lattice sites. The lattice structure of 102 , 10-1 I 1 I 1 1019 1020 102' Total As concentration/Atorns ~ m - ~ Fig. 9. Dependence of the diffusion coefficient on the concentration of As for normal thermal annealing at lOOO"C23 Depthlym Fig. 8. Redistribution of As as a function of annealing temperature and time. 1,150 keV, 50 nm Si02, 9 x 1015 atoms cm-3; 2, T = 950"C, 120 min; 3, T = lOOO"C, 60 min; 4, T = 950"C, 480 min; 5, T = 1000 "C, 240 min Systematic investigations enable the analyst to determine the dependence of the diffusion coefficient of As on dopant concentration for a given temperature.23 Fig.9 shows the ratio of extrinsic over intrinsic diffusion coefficient DIDi as a function of arsenic concentration at 1000 "C. The diffusion coefficient reaches a constant level at concentrations above about 2 x 1020 atoms cm-3 owing to the formation of clusters (see later), which have a much lower mobility. Di is of the order of 10-15 cm2 s-1 for 1000°C under conditions of normal thermal annealing. By combining elemental analysis (SIMS, NAA and RBS) with electrical measurements the electrically active fraction of the dopant elements can be determined after annealing. Through systematic investigations the equilibrium between the electrically active and inactive fraction, i.e., the dependence of the "electrical solubility" on annealing temperature, can be established.25 Fig. 10 shows the equilibrium curve for arsenic at an annealing temperature of 1000°C. It is evident that a high dose implantation, such as 1016 atoms cm-2, corresponding to a maximum implantation concentration of about 1021 atoms cm-3, yields only a small fraction of electrically active arsenic atoms. silicon is still present on cluster sites but a stress zone is induced. Clustering may be seen as a preliminary stage to precipitation, but it is substantially different. Precipitates are formed when the chemical solubility is exceeded, clusters occurring already at concentrations below the chemical solubil- ity limit.For arsenic at 1000°C clustering starts at about 3 x 1020 cm-3 while the chemical solubility is 1021 cm-3. Incorpora- tion of the electrical equilibrium into diffusion models allows calculation of the distribution of the total dopant concentration and the electrically active fraction after annealing, as is shown in Fig. 11. m - 1020 102' 1 022 u1 Total As concentration/Atorns ~ r n - ~ Fig. 10. Equilibrium between electrically active and total As concen- tration for an annealing temperature of loo0 OC23292 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 I As+ Si 1017 0 0.1 0.2 Depthlym Fig. 11. Comparison of calculated and measured distribution of total and electrically active As after annealing. Implantation: 60 keV, 10’6 crn-,, 40 nm SiO,; annealing: lOOO”C, 20 min N,.(Simulation by R. Tielert.) Solid line, calculated elemental profile; open circles, SIMS; broken line, calculated electrical profile Because of the diffusion processes occurring at elevated temperatures, reactions take place which may lead to precipi- tation if the chemical solubility limit is exceeded. Such precipitates can be formed by dopant atoms during annealing, as in the instance of antimony (see Fig. 4). Precipitated dopant atoms are electrically inactive but influence diffusion. Other precipitates are from recoiled oxygen (Fig. 7). Fig. 12 shows such SiO, precipitates in the SIMS profile of oxygen. These precipitates act as getters for arsenic owing to the generation of lattice defects and cause local arsenic enrichments.23 Gettering of dopant atoms also takes place near the silicon - silica interface owing to lattice defects generated by SiO, precipitations, as can also be seen in Fig.12. Such precipitation zones may contain a large fraction of the imdanted arsenic, in the example represented in Fig. 12 about 30%. 102‘ m 1019 I I I I I I I I I 0 0.05 0.1 0.15 0.2 Depthlpm 102 .g t I e 3 + .- C 0, 0 > 0 U 10’ 2 8 U Fig. 12. Formation of SiO, precipitations and gettering of As in silicon and near Si02/Si interface.23 Implantation of As: 150 keV, 9.1015 cm-2; annealing: 950 “C, 480 min, NZ. Crosses, As (0, + Po, = mBar), open circles As (Cs+); triangles, 0 (Ar+); closed circles 0 (Cs+). The last two are after etching of Si02 Physical defects (point defects, dislocations, etc.) act as precipitation nuclei.This is revealed by TEM, as shown in Fig. 4. In general, TEM and even EPMA provide valuable information about precipitation effects,26.27 so that they are complementary to SIMS. Diffusion during oxidation. Thermal oxidation is carried out typically at 1000 “C and therefore causes redistribution of the dopant elements. Oxidation in a dry or wet atmosphere generates a large number of interstitials in the surface zone of silicon, owing to the stress induced by the volume expansion during oxide formation ( Vsioz : Vsi = 2). These interstitials strongly influence the diffusion coefficient. The formation of the silica layer has the effect of increasing the diffusion coefficient due to the generation of interstitials for those dopant elements which show an interstitial-type mechan- ism for diffusion [boron, arsenic and phosphorus : oxide enhanced diffusion (OED)].For antimony, however, which exhibits a vacancy mechanism of diffusion, the diffusion coefficient is reduced because vacancies recombine with interstitials generated [oxide retarded diffusion (ORD)28]. Fig. 13 shows the effect of OED for boron. The profile obtained in an oxidising atmosphere is much deeper than the diffusion profile resulting under inert conditions. Another important redistribution effect is segregation of the dopant elements during oxidation. 1019 t I- Originat interface I Depth/pm Fig. 13. Influence of oxygen atmosphere on diffusion of B in silicon.23 Broken line, diffusion profile obtained for inert conditions; solid line, diffusion profile obtained in oxidising atmosphere under the same annealing conditions (9OO0C, 100 min).Sample structure: B implant (25 keV, 1013 cm-2 through 40 nm SiOz), 100 mm CVD SiO, (430°C); 100 nm Si3N4, 750°C (on one half of the wafer), oxidation at 900 “C, 100 min Depending on the segregation coefficient between silicon and silica (kSi/SiO ), a dopant element will either be enriched in the silica layer (2 < 1) or depleted ( k > 1). Enrichment in the silica causes a depletion in the zone of silicon near to the silica (“pile down”), whereas depletion in the silica causes enrich- ment in the silicon (“pile up”). Boron migrates into the silica,29 while arsenic, phosphorus and antimony are pushed off the oxide and pile up at the interface.30 The precise determination of the segregation coefficient of the individual dopant elements is of great significance for modelling “pile up” and “pile down” effects.Fig. 14 shows the segregation of arsenic between silica and silicon under con- ditions of thermal oxidation at 1000 “C. From the quantitative SIMS profile a segregation coefficient kSilSiO2 = 100 could be determined. Segregation coefficients for boron as a function of temperature have also been determined from quantitative SIMS profiles.31 Segregation of boron is a particularly severe problem in field oxidation. Typically, a dose of 1013 cm-2 is implanted into theANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 293 1022 I 1 E i I I 0.20 0.40 0.60 Depthiym Fig. 14. Determination of the segregation coefficient of As between Si02 and Si by SIMS.23 Process steps: 1, implantation of As through 30 nm Si02 (100 keV, 1016 cm-2); 2, oxidation in O2 + 3% HCl at lOOO”C, 10 min (50 nm of oxide are formed); 3,400 nm CVD-Si02 at 900 “C, 260 min, partially etched off before analysis field region.After oxidation only a dose of about 5 X 1011 cm-2 is present in the field region owing to outdiffusion of boron into the field oxide. On the basis of fitting parameters in process models to experimental data a fairly precise prediction of the behaviour of the dopant elements can be given. The parameters in the process models are valid for a certain range of experimental conditions. On the basis of good accuracy of analysis one dimensional modelling, as shown in Fig. 11, can be extended to two spatial dimensions. Fig.15 shows an example of two dimensional simulation of the distribution of the dopant elements in the finished MOS transistor. 0 Irm Fig. 15. Two-dimensional modelling of the distribution of the dopant elements in an MOS transistor: lateral distribution (from Tielert) Further Trends In silicon technology the trend to miniaturisation and complex- ity continues. This requires a still more accurate characteris- ation of the physical and chemical processes occurring during device production. The chemical and geometric surface structure of wafers as a function of surface treatment parameters is of fundamental interest. Scanning tunneling microscopy (STM) (Fig. 16), high resolution electron energy loss spectrometry (HREELS)32 and XPS,33 possibly with synchrotron radiation, combined with quasi-static SIMS34 will be of greater significance.For dopant element characterisation accuracy, sensitivity and spatial resolution is expected to be improved by the development of still more powerful instrumentation. SIMS seems to offer the greatest potential for this development. High resolution imaging and analysis by means of electron beams is certainly one of the key areas of progress. A variety of techniques ranging from high voltage transmission electron microscopy (HVTEM) to sub-micron scanning Auger electron microscopy (S-AES), and from high resolution X-ray analysis to trans- mission electron energy loss spectrometry (TEELS) imaging will be used on a larger scale. For structure analysis, computerised double crystal X-ray topography seems to be particularly promising.36 Fig.16. STM image of the (111) surface silicon. The distance between the topographical lines corresponds to 0.3 nm (from Binnig and R ~ h r e r ~ ~ ) Another important aspect, from an analytical as well as a technological point of view, is the combination of different analytical techniques to an analytical system, with greatly improved total information content. One of the most promis- ing systems combines TEM and SIMS for the study of the interaction of physical defects and dopant elements. Support of the research activities on which this paper is based by the Austrian Scientific Research Council (Projects No. 4508 and S 43/10), the Austrian National Bank, the Federal Ministry for Science and Research, the Central Research Laboratories of Siemens, Munich, and Wacker Chemitronic, Burghausen, is gratefully acknowledged. The author thanks the following colleagues for their excellent cooperation and support of this work: Professor Dr.H. Potzl, Dr. E. Guerrero, Dr. G. Stingeder, Mr. K. Piplits, Dr. R. Tielert and Dr. L. Mader, Dr. P. Eichinger, and Prof. W. Chu. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. References Electronics, January 12, 1984. Bardeen, J., and Brattain, W., Phys. Rev. 1948, 74, 230. Shockley, W., Bell Syst. Tech. J . , 1949, 28, 435. Deal, B. E., and Crossley, P. A., Ann. Rev. Mater. Sci., 1981, 11, 321. Plummer, J. D., et al., “Computer Aided Design of Integrated Circuit Fabrication Processes for VLSI Devices,” Rep. No. TR: DXG 501-84, Stanford University, CA, USA, July, 1984.‘ Antoniadis, D. A., Hansen, S. E., and Dutton, R. W., Integrated Circuits Laboratory, Stanford Electronics Labora- tories, CA, USA, Rep. No. 5019-2, 1978. Selberherr, S., “Analysis and Simulation of Semiconductor Devices,” Springer, Wien, Austria, 1984. Grasserbauer, M., Zolotov, Yu. A., Morrison, 6 . H., Stingeder, G., Karpow, Yu, A., and Gimmelfarb, F. A., Pure Appl. Chem., in the press. Ryssel, H., and Ruge, I., “Ionen Implantation,” Teuber, Stuttgart, FRG, 1978. Zinner, E . , J. Electrochem. SOC., 1983, 130, 199. Stingeder, G., et al., Fresenius 2. Anal. Chem., 1983,314,304. Evans, C. A., and Blattner, R. J., Ann. Rev. Mater. Sci., 1978, 8, 181. Magee, Ch. W., Nucl. Instrum. Meth., 1981, 191, 297.ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 294 14.15. 16. 17. 18. 19. 20. 21. 22. 23. 24. Benninghoven, A., et al., “Secondary Ion Mass Spec- trometry,” Springer, Berlin, 1978, 1980, 1982, 1984. Chu, W. K., Mayer, J. M., and Nicolet, M. A., “Back Scattering Spectrometry,” Academic Press, New York, 1978. Feldmann, L. C., and Poate, J. M., Ann. Rev. Mater. Sci., 1982, 12, 149. Stingeder, G., Thesis, Technical University of Vienna, 1983. Grasserbauer, M., and Stingeder, G., Trends Anal. Chem., 1984, 3, 133. Narajan, J., and Holland, W. O., J. Electrochem. SOC., 1984, 131, 2651. Kolbesen, B. O., and Strunk, H. P., “Analysis, Electrical Effects and Prevention of Process-Induced Defects in Silicon Integrated Circuits,” VLSI Electronics: Microstructure Science, Volume 8, Academic Press, New York, in the press.Brodie, I., and Muray, J. J., “The Physics of Microfabri- cation,” Plenum Press, New York, 1982. Ryssel, H., Lecture, Technical University of Vienna, June 14, 1984. Guerrero, E., Thesis, Technical University of Vienna, 1984. Guerrero, E., Potzl, H., Stringeder, G., Grasserbauer, M., and Tielert, R., “As-Implantation through Si02: O-Recoil and Gettering,” in preparation. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. Guerrero, E., Potzl, Tielert, R., Grasserbauer, M., and Stingeder, G., J. Electrochem. SOC., 1982, 129, 1826. Song, H. S., et al., J . Electrochem. SOC. Solid State Sci. Technol., 1982, 841. Pennycook, S. J . , Narayan, J., and Holland, 0. W., J. Appl. Phys., 1983, 54, 6875. Guerrero, E., Potzl, H., Stringeder, G., Grasserbauer, M., Piplits, K., and Chu, W.K., “Annealing of High Dose Sb-Implanted Single Crystal Silicon,” J . Electrochem. SOC. , in the press. Blanchard, B., Hilleret, N., and Quoirin, J. B., Radioanal. Chem., 1972, 12,85. Schwarz, S. A., et al., J . Vac. Sci. Technol., 1978, 15, 227. Charitat, G., and Martinez, A., J. Appl. Phys., 1984,55,2869. Ibach, H., Bruckmann, H. D., and Wagner, H., Appl. Phys., 1982, A29, 113. Grunthaner, F. J . , Grunthaner, P. J., Vasquez, R. P., Lewis, B. F., and Maserjian, J., J. Vac. Sci. Technol., 1979,16, 1143. Stingeder, G., Grundner, M., and Grasserbauer, M., “Investi- gation of Surface Contaminants on Silicon Wafers with SIMS,” in preparation. Binnig, G., and Rohrer, H., Surf Sci., 1983, 126, 236. Werner, H. W., Fresenius 2. Anal. Chem., 1983, 314, 274. I Three of the Worldb leading Analvtical Tournals The Analyst An international journal of high repute containing original research papers on the theory and practice of all aspects of analytical chemistry drawn from a wide range of sources. It also publishes regular critical reviews of important techniques and their applications, short papers and urgent communications (which are published in 5-8 weeks) on important new work, and book reviews. 12 issues per annum (plus index) Analytical Proceedings Analytical Proceedings is the news and information journal of the Analytical Division. 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ISSN:0144-557X    

DOI:10.1039/AP9852200287

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年代:1985

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ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 295 Reversed-p hase Separations The following are summaries of four of the papers presented at a Joint Meeting of the Chromatography and Electrophoresis Group and the East Anglia Region held on April 16th, 1985, in Southend College of Technology. The Application of Reversed-phase High-performance Liquid Chromatography in the Food Analysis Laboratory A. D. Jones Unilever Research, Colworth House, Sharnbrook, Bedfordshire MK44 7 LQ Reversed-phase high-performance liquid chromatography (RPHPLC) accounts for something approaching 80% of all HPLC applications. The reasons for its popularity can perhaps be understood in the light of the following: firstly, the phases are relatively easy to prepare, reproducible and stable; R-c/S-D Glucose N-oS03- Fig.1. Glucosinolate structure secondly, the elution order is predictable, based on the degree of hydrophobicity of the solute; thirdly, the predominant mobile phase component is water, which is inexpensive, non-toxic and non-flammable; and fourthly, reversed-phase chromatography is very versatile, being capable of chromato- graphing both non-polar and ionised or ionisable species. With respect to the fourth point above, there are three prime modes in which reversed-phase columns can be seen to operate: hydrophobic, ion-suppression and ion-pairing. Applications The following applications will highlight the use of these three modes, and at the same time demonstrate the breadth of application of the technique within our own Laboratory. The separation of polycyclic aromatic hydrocarbons (PAHs) is carried out in the straight hydrophobic mode.PAHs in food are usually the I result of contamination from either the environment or treatment such as smoke drying. The analysis demands the detection and determination of very low levels (p.p.b.) of hydrocarbon and their native fluorescence is used as the basis for their detection. A number of PAHs can be separated in a single chromatographic run on CI8 by using a methanol - water mobile phase. Maximum sensitivity can be achieved by programming the detector to switch wavelengths prior to the elution of each peak, permitting the detection of I OH CH3- / Inject \ 100% H7O I I I 1 I \ I 50 40 30 20 10 0 Time/min Fig. 2. 30 min gradient from water to water - acetonitrile (88 + 12); flow-rate, 1 cm3 min-1; detection, ultraviolet at 228 nm Separation of glucosinolate standards.Chromatographic conditions: column, 18 cm X 0.49 cm i.d., 5 pm CIS; mobile phase,296 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 sub-p.p.b. levels of, for example, anthracene, pyrene and perylene. Glucosinolates (Fig. 1) are a group of naturally occurring compounds found in rapeseed meal and brassicas. After desulphonation with aryl sulphatase, the desulpho- glucosinolates can be separated by reversed-phase separation in the hydrophobic mode using a linear acetonitrile gradient in water (Fig. 2). The separation exemplifies the predictability of elution order on reversed phase, with, for example, K' penten-4-yl > buten-3-yl > allyl. The analysis of hydroxyproline (HYP) is a good example of the use of ion pairing.Determination of HYP after protein hydrolysis is the accepted procedure for the determination of collagen. We use the fluorogenic reagent 7-chloro-4- nitrobenzo-2-oxa-l,3-diazole (NBD-C1) with which to deriva- tise the amino acid. This reacts an order of magnitude faster with secondary than with primary amines, thereby effectively reducing the interference from other amino acids present in the hydrolysate. By using acetate buffer - acetonitrile containing sodium octyl sulphonate ion pair reagent, interfering deriva- tives of NBD-C1 can be retained longer on the column, thereby permitting separation of NBD-HYP. Long chromatographic run times can be avoided by using column switching, which prevents the unwanted derivatives from eluting on to the analytical column, With use of this procedure HYP levels of between 0.05 and 12.5% are routinely determined in meat and meat products. Another rather novel use of reversed-phase ion pairing can be demonstrated by the determination of ions, i.e., ion chromatography.The column is prepared by dissolving cetyl- trimethylammonium bromide (CTAB) in methanol - water (7 + 3) and adding C18 phase to form a slurry. The slurry is then packed in the normal manner, using methanol - water (1 + 4) with which to pack the column down. Separation of various anions can be achieved by using a sodium carbonate or sodium hydrogen carbonate buffer with conductivity detection. An Aminex A-5 cation exchanger in the H+ form sited imme- diately after the analytical column removes sodium ions and converts C032- and HC03- to H2C03, thereby considerably reducing the background conductivity due to the buffer.This system permits the quantification of pg ml-1 levels of, for example, chloride, nitrate, nitrite, sulphur dioxide and phos- phate. A large number of separations carried out on reversed-phase entail ionisation suppression or control either to increase retention or to avoid peak tailing, and the following examples fall into this category. Nt-methylhistidine (NMeHis) is formed post-translationally in the muscle proteins actin and myosin to which it is unique, and this has led to the proposal that it be used as a quantitative index for lean meat (muscle). Following protein hydrolysis, NMeHis is reacted with fluorescamine and incubated with acid for 1 h.Fluorescamine reacts with all primary amines present in the hydrolysate, resulting in a potentially difficult separation problem. The incubation with acid, however, overcomes this problem because it destroys all of the derivatives apart from those with a 2-(4-imidazolyl)-ethylamine structure, i. e . , histi- dine and Nf-methylhistidine. The two amino acids are then separated on reversed phase by using methanol - acetate buffer at pH 4 (1 + 1). Initial results from this analysis on a range of beef muscles show that whilst prime cuts, e . g . , topside and silverside, contain a fixed level of Nt-methylhistidine per gram of protein, levels in manufacturing cuts such as flank and head vary considerably. There would appear, therefore, to be difficulties in using Nt-methylhistidine as a quantitative index for lean meat.Separation of the metabolites of caffeine can be carried out on reversed-phase by using a methanol gradient in the presence of 2% acetonitrile and 0.05% acetic acid. Metabolism proceeds via demethylation of caffeine itself (xanthine metabolites) or after its conversion to trimethyluric acid (uric acid metabol- ites). In both instances a total of three dimethyl and three monomethyl metabolites are formed. Fig. 3 shows the separa- tion of these metabolites in a sample of rat urine, using ultraviolet detection at 274 nm. A total of 14 metabolites at the p.p.m. level can be determined in a 50-min run. 7 M 7n IU I 1,7 3,7 DMX 1 MU I '7DMU 1 MX I MX 1.3 DMX TMU 1,3,7 TMX Fig.3. Caffeine metabolites in rat urine. Chromatographic condi- tions: column, 15 cm X 0.49 cm i.d., 5 pm CIS; mobile phase, gradient water - methanol - acetonitrile - acetic acid (94 + 4 + 2 + 0.05) to water - methanol - acetonitrile - acetic acid (83 + 15 + 2 + 0.05) over 15 min; flow-rate 1 cm3 min-1; detection, ultraviolet at 254 nm The author thanks Messrs. Ebden, Dacombe and Homan for their contributions to the lecture. Protein Separations by Reversed-phase HPLC R. L. Patience Department of Chemical Endocrinoiog y, St. Bartholomew's Hospital, London, EClA 7BE The mechanism of protein separation on reversed-phase columns is thought to occur via a one-off multiple site adsorption - desorption step. This process is controlled by a critical change in organic solvent composition over a very narrow range, and as a result it is almost always necessary to use gradient elution if two or more proteins require separation.Very short columns (1-10 cm) can be used without affecting resolution or loading capacity, because adsorption and then desorption is a once-only step. The conventional reversed-phase column is a C18 (ODS)ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 297 material on a silica base, with 6-10 nm pore diameters. For proteins and many peptides this column has disadvantages both with regard to the alkyl chain length and the pore size. Large biological molecules diffuse only slowly, if at all, into and out of -8 nm silica pores, leading to broad asymmetric peaks, reduced recoveries, poorer separation and lower loading capacities.Many hydrophobic proteins can prove difficult to elute from CI8 phases, so there is a trend towards the use of shorter alkyl chain length columns such as C8, C4 or C3. As a general rule, protein separations tend to be carried out under acid conditions (pH c 4). This is because any free hydroxyls on the silica are protonated, thus reducing non- reversed-phase adsorption. Acid conditions also ensure that any protein is in a single ionic state (carboxyls as COOH; amino groups as NH3+), and the addition of counter anions can vary hydrophobicity and aid separations. As a result of those effects, peak shapes tend to be sharper and recoveries are improved. To summarise, then, optimum typical conditions for protein separations would be gradient elution (using acetonitrile or propanol as organic solvent) under acid conditions, with a wide pore (230 nm) CI8 or shorter alkyl chain length column.A dramatic example of the effect of increasing pore diameter and reducing alkyl chain length is the comparison of the chromatography of picogram amounts of 1251-dynorphin 1-13 on a Varian Micropak CI8 (6-8 nm pores) and an Altex Ultrapore C3 (30 nm). In the former chromatogram, dynorphin 1-13 had a retention time of -40 min, eluted over a period of 20 min, and showed only 50% recovery. In complete contrast, on the Ultrapore column the retention time was 11 min, the peak width less than 2 min and the recovery nearly 90%. Many biochemists are interested in the recovery of biological activity following chromatography. Unfortunately, there seems to be no concensus on the effects on protein confor- mation during reversed-phase HPLC, nor are there general trends discernible when the bioactivity of various compounds is determined after analysis. The only conclusion to be drawn is that some proteins (whether they be enzymes, hormones or otherwise) are “denatured” by either stationary phase or solvent effects (this may or may not be irreversible) and biological activity is recovered wholly, partly or not at all, depending on the protein and the chromatography conditions used! In order to illustrate the types of separations that can be achieved, two examples chosen were the analysis of human pituitary growth hormone (GH) variants1 and of circulating growth hormone-releasing factor (GRF) forms.2 Human monomeric GH is a single chain, 191 amino acid protein with two loops (one large, one small) formed by disulphide bridges.It has an approximate relative molecular mass of 22000 dalton. A number of other forms exist in the pituitary, including a 20 000 dalton form (6 32-46), monomeric charge variants (e.g., deamidated forms), disulphide bridge - cleaved monomer forms, a dimer and possibly a higher relative molecular mass form. Reversed-phase HPLC can resolve these forms into at least four classes: the 22 000 dalton form plus all other non-cleaved forms; disulphide bridge - cleaved forms; dimer; and another high relative molecular mass form (eluting in that order). One other component, eluting prior to the 22 000 dalton form, remains unidentified.Human GRF is based on a 44 amino acid chain, and three forms have been identified previously in the hypothalamus and other tissues: GRF 144, 1-40 and 1-37. These forms have been found in circulating plasma in a diseased subject with high GRF levels. Further work is in progress on circulating forms in normals and other diseased people. References 1. Patience, R. L., and Rees, L. H., J . Chrornatogr., 1985, 324, 385. 2. Penny, E. S., Patience, R. L., Sopwith, A. M., Was, J . A. H., and Rees, L. H., J. Endocrinol., 1985, 105, Rl-R4. Reversed Phase Chromatography in an Industrial Setting D. Lockwood and M. A. Russell BDH Chemicals 1 td., Broom Road, Poole, Dorset BH 12 4NN Analysis at BDH is concerned largely with trace analysis rather than with the determination of major constituents. Among the users of laboratory chemicals several trends are clearly discernible. Firstly, there is concern with costs, and for this reason there is a trend towards reducing the amounts of chemicals used in testing procedures.Secondly, there is a general trend towards increasing the sensitivity of the tech- niques used, partly generated by changes in technology, particularly in instrumentation, and partly by the desire to use smaller volumes of chemicals. Thirdly, there is the demand for purer and purer reagents. This relates to the other two trends, because if one is using more sensitive techniques and smaller volumes of laboratory reagent then the effect of impurities in those reagents becomes more noticeable. These trends are particularly obvious in the field of clinical chemistry, but are to be found in almost every type of laboratory. To some extent, these trends were already to be seen over 50 years ago and resulted in the introduction of AnalaR chemi- cals.Further recognition has been given to them in the latest edition of AnalaR standards. For the first time HPLC has been introduced, essentially as a means for determining trace contaminants. The key problems in trace analysis (or perhaps in any analytical process) are separation, identification and quantifi- cation. Separation can by carried out by many processes including extraction, crystallisation, precipitation, distilla- tion, chromatography or electrophoresis, but of all these processes chromatographic procedures are perhaps the most versatile and generally applicable, as well as offering at least a measure of quantification and identification. Gas - liquid chromatography (GLC) can give rapid separa- tions, accurate quantification and a degree of identification by retention time, but is limited in its range of applicability to reasonably volatile materials of medium to low polarity.Thin-layer chromatography is more generally applicable, but is at best only semi-quantitative. HPLC appears to offer advan- tages over both. The volatility restriction of GLC is replaced by one of solubility, making it possible to analyse almost any sample. Quantification, although not quite as simple as in GLC, because of a much greater variation in response factors, is reasonable. However, what really makes HPLC such a powerful tool is the ability of reversed phase packing materials to separate polar substances and, by their nature, it is in polar substances that we are usually most interested as they are inherently the most active and reactive and hence of particular interest. Nevertheless, it is all too easy to go overboard, to assume reversed phase to be the be all and the end all of techniques.298 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 We believe reversed phase chromatography should be seen as just one of the techniques available to us, as part of our analytical armoury. Almost all reversed phase HPLC uses water as a constituent of the mobile phase.The quality of that water is of great importance, especially in gradient systems, as trace contami- nants can be adsorbed on to the column when the water content is high, to be eluted subsequently, producing spurious peaks.We investigated this problem several years ago, and found that such impurities were present in practically every sample of water that we tested. Published work has variously suggested that such contaminants may be phthalate plasticisers or polycyclic hydrocarbons. The test that we adopted was to flush a column with acetonitrile, switch via a gradient to the water under test, pump a total volume of 40 ml through the system and then revert to acetonitrile via a gradient. In a typical separation two large and three small peaks were eluted. Much effort went into solving this problem, which was eventually achieved. This quality can only be maintained by constant vigilance and strict quality control, and to this end we check the product both before and after packaging.Of course, one does use solvents other than water and there have been substantial improvements in quality in recent years, as indicated in our latest catalogue on chromatography systems and HiPerSolv high performance HPLC solvents. The availab- ility of water, methanol, and acetonitrile of high quality now makes it possible to carry out serious gradient work in the far ultraviolet region. For an example, polyethylene glycols can be chromatographed using a water to acetonitrile gradient (5- 40% acetonitrile) with detection at 198 nm. The next point to be considered concerns the choice of columns, Most of the separations discussed in this paper have been carried out on Lichrosorb RP18.However, that column material may not always work. For example, we needed to analyse a mixture of methylenebisacrylamide and acrylamide. In this instance Lichrosorb RP18 gave poor retention and little or no separation. Spherisorb gave much better retention and a good separation. Such differences between reversed phase columns from different manufacturers have been reported in the literature and some interesting comparative studies have been carried out by Roger Smith at Loughborough University. In general, these differences are probably caused by differ- ences both in the silica support used, and in the extent of capping. It doesn’t follow that one manufacturer’s columns are better than another’s except in the context of a specific separation.What must always be kept in mind is that if one’s usual system does not work, changing to a nominally similar column from another manufacturer may. The optimum choice of detection wavelength is also of great importance, at least to those of us who have not got at our disposal the latest computerised diode array detector. In this context 1 want to discuss a separation investigated during our revision of AnalaR Standards in preparing for the recently published 8th Edition. This is the determination of resorcinol and diresorcinol in phloroglucinol. In the 7th Edition these compounds were determined by crude, qualitative tests. When acetylated and layered with sulphuric acid, any diresorcinol present gave rise to a violet ring, while a molten reaction with phthalic anhydride and zinc chloride, followed by dissolution in water and addition of base, gave a fluorescence reaction if resorcinol was present.The problem in detection was whether a suitable single wavelength could be chosen which would detect all three substances. In fact, this proved to be very easily done, the wavelength finally chosen being 284 nm. The added bonus was that phloroglucinol, under these conditions, had a fairly low response factor, making it much easier to get all three peaks on scale. Detection limits were 0.001% for resorcinol and 0.005% for diresorcinol. Three further examples from our work on AnalaR Standards will now be discussed. Naphthalene is a known contaminant in 1- and 2-naphthol. The 7th Edition had a crude limit based on the opalescence formed with industrial methylated spirit and ammonia.Isocratic separation on RP18 with 55 + 45 methanol - water proved very simple, naphthol being very rapidly eluted under these conditions, and naphthalene being retarded to emerge with a retention time of about 10 rnin. The detection limit for naphthalene is below 0.001%. The determination of nitrilotriacetic acid in EDTA disodium salt is of some considerable importance, as this substance is commonly used as an additive for controlling contamination by trace metals. In this respect, the presence of other metal binding reagents is especially undesirable. The 7th Edition of AnalaR Standards included a polarographic method, but this is cumbersome and non-specific, and a better, more specific method was felt to be needed.Unfortunately, this determination proved somewhat less than successful. Application of a published procedure (Parkes, Caruso and Spradling, Anal. Chern., 1981, 53, 2154) gave a satisfactory separation from EDTA but the presence of an unidentified contaminant made it impossible to achieve a detection limit of less than 200 p.p.m. This was considered too close to the AnalaR limit of 300 p.p.m., and could not compete with the detection limit of about 5 p.p.m. which was achieved by polarographic means. The last separation that we want to describe concerns p-toluidine. The objective here was to determine traces of toluene, 4-nitrotoluene and o-toluidine. By use of reversed- phase chromatography we were able to separate the first two of these from p-toluidine, but we could not separate ortho and para.We therefore used a normal-phase system. We found not only that a satisfactory separation of all three contaminants and the main peak was readily achieved, but that a fourth contaminant peak was present, and this was subsequently identified as rn-toluidine. This is clearly a case (if you’ll forgive us) of lFtting R(eversed) P(hase) RIP. Reversed Phase HPLC Packings Today-A Better Understanding of the Chemistry Fredric M. Rabel Whatman Inc., 9 Bridewell Place, Clifton, NJ 07014, USA There are many versions of bonded reversed phase HPLC packings now available. Unfortunately, there are many vari- ables in the manufacture of each which lead to quite different inherent selectivities. It has been a problem to define the differences in the bonding chemistries so that general classifica- tions can be made. Most chromatographers agree that the minimum information that must be obtained is that including chain length, functionality of the bonding reagent (mono-, di-, or tri-), surface area and pore size of silica and possible end capping. Some of this information is available from the manufacturers, more is being researched by hydrolysis - GC and pyrolysis - GC techniques.Of equal interest, however, are the experiments into bonded phase modifications that have been investigated lately by Sander and Wise.’ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 299 Before getting into these bonding experiments, it is of interest to discuss the two most widely used supports for bonded phases.These are the irregular and spherical silicas. It is often asked if one or the other might be better. Fine particles used to give the irregular silicas higher back pressure after packing, and high or low inherent pH values (versus the desired pH around 7) used to be a problem with spherical silicas. With the newer sizing and synthetic routes, either can be used with equal confidence. It has been stated by Ohmacht and Halasz2 that equivalent results can be obtained with irregular or spherical silicas. The biggest advantage each gives is more variety in the pore size and surface area on to which bonded phases can be made. Returning to the bonding of reversed phases, there are generally two reactions to bond to silanols, those using mono- or tri-functional silanes, XSiR3 or X3SiR.The first gives what are called monomeric bonded phases, the second gives polymeric bonded phases as the extra functional groups in the presence of water can hydrolyse and cross-link with other reagent molecules. Theoretically, the R3SiX hydrolyses to (R3Si)20, which would be washed from any bonding reaction mixture. Verzele and Mussche3 found, however, that water added even to monofunctional silanes increased the percen- tage of bonded phase added. They postulated that the R3SiOH first formed by hydrolysis reacts even faster or more com- pletely with silanols than does the original reagent added. Recently, too, Sander and Wise1 have investigated the synthesis of polymeric phases, as these have been found to be best for the separation of priority pollutants and polyaromatic hydrocarbons.They found that increasing the pore size increases the amount of polymeric character the phase has, as indicated by the separation of a trio of PAHs used to distinguish between monomeric and polymeric character. They also found that the order of water addition did not change the percentage of carbon or character of the phase. Running a typical reaction without the silica, they found a polymeric (-5000 M,) white floating precipitate, which slowly dissolved to give a clear solution on refluxing. Addition of the silica after the solution clearly yielded a packing of monomeric character. Studies were also carried out on the acid and base washing of the silica, their effect on the final bonded phase and on the change in the pore size with bonding.These studies continue to show the reasons for the variation found in reversed-phase packings. Each gives an inherent selectivity when used with a given mobile phase. Whether monomeric or polymeric on irregular or spherical support, each can be a potentially useful phase for reversed phase HPLC. References 1. 2. 3 . Sander, L. C., and Wise, S. A . , J . Chromatogr., 1984,316,163. Ohmacht, E., and Halasz, I . , Chromatographia, 1981, 14,216. Verzele, M., and Mussche, P . , J . Chromatogr., 1984,254, 117. Brief Contents: Chemical Biographies; Chemical Education and Chemical Institutions; Recent Developments Introduction; in the History of chemistry Edited by C. A. Russell This book is intended primarily to inform chemists of recent progress in the history of chemistry.It originated from an initiative of the Historical Group of the Royal Society of Chemistry who for some considerable time had been aware of a rising surge of interest amongst chemists in the history of their subject. Yet there was also considerable frustration in obtaining reliable and up-to-date information, in understanding recent trends and in perceiving the relevance to specific problems of some of the less obviously 'chemical' writing of the last few years. Those with whom the Group was in touch included chemistry teachers wishing to introduce-perhaps only occasion a I I v- h i s t o r i ca I e I e m e n t s i n t o t h e i r sc h o o I c u r r i c u I a. Chemistry to 1800; General and Inorganic Chemistry; Organic Chemistry; Physical Chemistry; Analytical Chemistry; Biochemistry; Instruments and Apparatus; Industrial Chemistry; Chemistry by Location in Western and Central Europe; Appendix I Periodicals for the History of Chemistry; Appendix II Some Useful Addresses; Author Index; Subject Index: People; Subject Index: Themes. Hardcover 344pp. ISBN 0 85186 917 3 Price f27.50 ($36.00) RSC Members f12.00 Others who expressed both interest and frustration were members of university and polytechnic chemistry departments, chemists in industrial research and those who had taken early or normal retirement. These are the readers for whom this book has been published, although it is hoped that professional historians of science may also find it to be of interest and value in its general surveys of the literature. Ordering: Non-RSC Members should send their orders to: The Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts. SG6 lHN, U.K. RSC Members should send their orders to: The Royal Society of Chemistry, Assistant Membership Officer, 30 Russell Square, London, WC1 B 5DT.

ISSN:0144-557X    

DOI:10.1039/AP9852200295

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

300 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 On-line Analysis The following is a summary of one of the papers presented at a Joint Meeting of the Analytical Division, The Automatic Methods Group and the Institute of Measurement and Control held on December 5th, 1984, at the Health and Safety Executive, London, N.W.2. Summaries of four other papers from this meeting were published in the June, 1985, issue (p. 177). On-Line Measurement of Sulphur Dioxide in Flowing Gases R. D. Snook* and P. E. Zaftt Chemistry Department, Imperial College of Science snd Technology, London SW7 2AY One of the outstanding problems in gas analysis is the real time on-line analysis of toxic gases at low concentrations. We have adopted two approaches to try and solve this problem. The first was to investigate the use of dispersive infrared detection and the second was to employ coated piezo-electric mass transducers as specific sensors.The infrared technique has provided us with much background information on flowing systems and on our ability to prepare sulphur dioxide standards for use with the piezo-electric crystals. It also allows us to carry out independent tests to assess the accuracy of our piezo-electric crystal sensor. The infrared technique uses either the 7.35 pm absorption band or the 8.3 pm band for quantitative measurements. For static measurements a perspex cell with potassium chloride end windows is filled with a gas mixture prepared by serial dilution using a vacuum-line apparatus. The vacuum line allows us to determine sulphur dioxide concentrations by pressure.To achieve this we admit sulphur dioxide to the vacuum line and pump it down to a known pressure (measured with a vacuustat). A bulb to which the cell is attached in the apparatus is isolated at this pressure of sulphur dioxide and the apparatus is purged with argon. Argon is then admitted to the bulb and cell and the pressure adjusted to 1 atmosphere. We can therefore conveniently prepare known concentrations in this way ranging from a few volume parts per million (v.p.p.m.) to 100% sulphur dioxide. The cell is then placed in the infrared spectrometer. For flowing sulphur dioxide measurement a gas-tight syringe is used to collect sulphur dioxide from the bulb via a septum; it is injected into a flowing steam of argon, which passes through the cell.By using the 7.35 pm band (Fig. l), which is the most sensitive, we can obtain a linear relationship between the infrared absorption and the concentration of sulphur dioxide between the detection limit of 100 ng (-1.0 v.p.p.m. at STP) and 2 mg (20 000 v.p.p.m. at STP) measured under static conditions. In order to extract signals at low concentrations from the antiquated electronics of the P-E 127 sodium chloride spectrometer we enlisted some modern technology and replaced everything behind the detector with a Research Machines 3802 microcomputer and a purpose built interface rack. This combination greatly increased the sophistication of signal extraction and data manipulation. Under flowing conditions the measurement is more difficult as the gas flow-rate plays an important role in determining the peak shape and duration as the transient injected sample of sulphur dioxide passes through the cell.For the purposes of the experiment the optimum gas flow-rate was set at 2.5 1 min-1, to * Present address: Chelsea Instruments Ltd., 5 Epirus Road, t Present address: Laboratory of the Government Chemist, Stam- London SW6 7UR. ford Street, London SE1. which 250 pl sample volumes of argon containing sulphur dioxide were injected. Of the possible interferences, water vapour is serious and this spectral interference can be avoided by using the slightly less sensitive 8.7 pm band. Wavelength/pm 3 4 5 6 7 8 9 10 15 I 1 , * - - - - - - I f i f - 2o t 1 I I , I I I I 1 4000 3000 2000 1800 1600 1400 1200 1000 800 650 Wavenumbedcm-' Fig.1. Infrared spectrum of sulphur dioxide The apparatus was also used to study the absorption and desorption of sulphur dioxide in plastic flexible pipes which are often used in laboratory experiments of this nature. We established that sulphur dioxide absorption can be severe when pipes are left overnight. In order to determine how severe this effect is, we evacuated the pipes and perspex cell after filling them with sulphur dioxide (100 p.p.m.), refilled them to atmospheric pressure with argon and recorded the infrared spectrum at 7.35 pm. No sulphur dioxide signal was observed, but after 30 min a measurable signal was obtained. Clearly, sulphur dioxide gradually desorbs from the cell surfaces. We have studied the desorption of sulphur dioxide from the cell by recording the cumulative sulphur dioxide absorbance at 2-min intervals.The desorption was shown to obey first order kinetics by plotting In ( A - A , ) versus desorption time. This effect could be serious for static or cumulative measurements, but is probably not important in the detection of transient sulphur dioxide concentrations as we carry these out with the piezo-electric crystal sensor. Piezo-electric Crystal Sulphur Dioxide Sensor The underlying principle of operation of a piezo-electric crystal is simple. Quartz, when cut on a particular plane, possesses the property of piezo-electricity . This phenomenon is caused by the symmetrical separation of charges in the crystal. If the crystal is deformed by a mechanical force, the charge separa- tion is changed and a potential is generated across the crystal.ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 I I , , 301 Fig.2. Schematic diagram of experimental arrangement for sulphur dioxide detection with a piezo-electric crystal sensor The phenomenon is utilised widely in such devices as cigarette lighters and gas cooker lighters. We can influence the behaviour of the crystal in another way; by applying an alternating potential to the crystal via two electrodes previ- ously deposited on to the surface, we can cause the crystal to oscillate. If we include the crystal in a tuned resonant circuit, or oscillator, we can cause the crystal to oscillate in a stable manner at its resonant frequency. It is in this mode of operation that piezo-electric crystals are employed widely in the electron- ics industry.For this application, the crystals are sealed hermetically into a can to prevent frequency changes as a result of changing temperature, humidity and capacitance effects. Tern peratu re/"C Fig. 3. The frequency variation of crystal A with temperature in the range 10-45 "C If we take the crystals out of the can it responds to changes in temperature by changing its resonant frequency. The tempera- ture coefficient associated with this effect is of the order 20 Hz "C-1 for a 10 MHz AT cut crystal of the type which we employ. The crystal responds in a similar way to a change in mass adsorbed or coupled to the surface and this explains its response to humidity. The equation which describes the change in frequency with absorbed mass is the Sauerbrey equation dMs A dF= -2.3 F2.106- where dMs is the solid mass adsorbed, A the area of absorbed mass and F the frequency.Therefore an increase in mass leads to a decrease in frequency. To use the crystal as a detector for sulphur dioxide, therefore, we have to coat the surface electrodes with a chemical that absorbs or desorbs sulphur dioxide specifically , and incorporate the crystal into an oscillator and detector cell through which the gas stream to be measured is passed. The detector cell which we have used has two jets on each side of the crystal to allow the gas stream, in this case argon containing sulphur dioxide, to impinge on the centre of the crystal, which is the most sensitive part. For the purposes of the experiment we have employed a test rig (Fig.2) in which we can quickly vary the environment of the crystal in terms of gas composition (using the gas dilution apparatus), temperature and water composition of the gas stream. The oscillator and frequency meter board of the interface rack are controlled by the Research Machines 3802 microcomputer. The crystal frequency can be compared with the crystal clock of the FM board for the accurate determi- nation of frequency changes. loo0 I Fig. 4. dioxide. Flow-rate, 60 cm3 min-1; injected volume 1 cm3 Calibration of crystal frequency with concentration of sulphur With this apparatus we can quickly assess the effect of temperature on our measuring crystal. For example, Fig. 3 shows the change in resonant frequency with temperature.Between 21 and 35 "C there is a steady change in frequency of 5 Hz "C-1 and at about 38 "C the crystal response changes to the opposite. This point is known as the turnover temperature of the crystal, where the temperature coefficient is 0. This region is therefore suitable for obtaining temperature indepen- dent measurements. Varying the water content of the argon stream which passes over the crystal also has an effect on the crystal frequency. We have studied these effects at different temperatures and from302 our results we can conclude that there is a significant effect of water vapour on the crystal response. Therefore, in order to make our measurements on sodium dioxide in a flowing argon stream, we have employed a hydrophobic coating which selectively absorbs sulphur dioxide.Its trade name is Quadrol, which is a large amine [NNN"'- tetrakis(2-hydroxypropy1)ethylene diamine]. To demonstrate that we can use this substance for sulphur dioxide measure- ments, we have studied the response of a coating to different concentrations of sulphur dioxide prepared in the gas dilution apparatus by injecting sulphur dioxide/argon mixtures into a flowing stream of argon (0.60 1 min-1). It is clear from Fig. 4 that we can detect 0.06 p.p.m. of sulphur dioxide injected in this way. We are able to achieve this detection because we are taking a discrete measurement. Long-term changes in temperature and humidity do not concern us as we have a measurement of the ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 background frequency change (which is a record of these effects) before and after each measurement of sulphur dioxide.A possible disadvantage is that, after the measurement, the desorption kinetics of sulphur dioxide from the crystal/Quadrol surface are slow and we therefore have a continuously sloping base line between each measurement caused by sulphur dioxide, which is still bound to the Quadrol from the previous measurement. Future work will be directed towards eliminating effects caused by humidity and temperature by independent measure- ment of the parameters, storage of this data as Fourier coefficients, obtained by Fourier analysis of the frequency response curves, and deconvolution of their effects by the solution of several simultaneous equations containing these coefficients.Hitherto, this would have been a difficult prob- lem, but we can now achieve this end by using our microcom- pu ter system. Environmental Chemistry VoI. 3 Senior Reporter H. J. M. Bowen A review of the literature published UP to the end of 1982. Disposal and Utilization of Sewage Sludge Possible Consequences of Sewage Sludge Disposal and Utilization and the Need for Monitoring Brief Contents: Tropospheric Ozone Ozone Sources in the Unpolluted Troposphere Photochemistry of the Clean Troposphere Ozone Distribution in the Troposphere Sinks of Ozone in the Unpolluted Troposphere Tropospheric Ozone Budget Ozone Formation and Destruction in Polluted Air Elevated Ozone Levels Biological Effects of Ozone Analytical Techniques Inorganic Deposits in Invertebrate Tissues Metal Deposits Ligand Binding Silica Deposition Urates Specialist Periodical Report ( 1 984) Hardcover 153pp 0 85186 775 8 Price f41 .OO ($74.00) RSC Members f27.00 The Environmental Chemistry of Organotin Com pou nds Toxicological Patterns of Organotins Analysis of Organotins at Environmental Levels Modes of Entry into the Environment Aqueous Chemistry Transformations in the Environment RSC Members should send their orders to: The Royal Society of Chemistry, Membership Officer, 30 Russell Square, London WClB 5DT. Non-RSC Members should send their orders to: The Royal Society of Chemistry, Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 1 HN, England. The Royal Society of Chemistry Burlington House Piccadilly London W l V OBN Degradation of Organotin Compounds Determination of Heavy Metals in Sewage Sludge Analysis of Sewage Slud e Selected Procedures for 8ludge Analysis

ISSN:0144-557X    

DOI:10.1039/AP9852200300

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

303 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 Equipment News Analytical Software Fein - Marquart packages for the IBM PC desktop computer include Mascot, which is for the analysis of mass spectral data. Spectral data are entered and dis- played on a screen in graphic form, facilitating the comparison of two un- knowns or of an unknown with a reference spectrum from one the Mascot libraries, of which currently there are two available on disk, one for environmental com- pounds, the other for forensic drugs. The Micro Powder Diffraction Search/Match (pPDSM) system enables the user to search the entire JCPDS powder diffrac- tion file or specified sub-files, selected by particular chemical or functional groups, specified elements or minimum accep- table quality. The Superstructure pack- age allows the user to draw, lable, mani- pulate and replicate complex structures using a touch-pen or a mouse.Structures and fragments can be shifted, rotated, mirrored, copied or deleted, and a chemi- cal structures library may be built up for retrieval and/or structure searching. pThermo, a package for thermodyn- amics, is soon to be added to the range. Heyden and Son Ltd., Datasystems Division, Spectrum House, Hillview Gar- dens, London NW4 2JQ. Data Station for Spectroscopy The data station adopted is the standard IBM PC environment, thus allowing the use of a wide range of business software, including SYMPHONY, FRAMEWORK, LOTUS 123 and WORDSTAR. The new infrared data systems can be based on the makers’ SP3 or PU 9500 Series of ratio recording spectrophotometers. Infrared software offers spectrum storage on dual floppy disk drives, co-addition to improve signal to noise ratio, derivative spectroscopy, quantitative analysis, spectral subtraction and a library search program.Two ultraviolet - visible spectroscopy data systems will shortly be released, combin- ing the PU 8600 single-beam or the PU 8800 double-beam scanning spectropho- tometer with the data station. Software packages are also announced. Pye Unicam Ltd., York Street, Cam- bridge CB12PX. Fluorescence Software Three packages have been introduced for use with the makers’ Series 7000 Profes- sional Computers and fluorescence spec- trometers. PECLS-3 is for instrument con- trol, data acquisition, storage and retriev- al, colour graphics display, printout and the mathematical manipulation of data.Routines are included for calculating first to fourth derivatives, peak tables, areas, difference spectra, normalisation and converting linear wavelength data to wavenumber. QUANT-~ is a quantitative program for multi-component analysis, without physical separation, of mixtures containing up to 15 components. PETLS software enables spectral data to be dis- played as a three-dimensional picture of the mixture or as a contour plot and it is especially useful for analysing complex mixtures such as crude oils. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Inductively Coupled Plasma Spectrometer The PLASMAKON S15 is a bench instru- ment for sequential analysis using an argon plasma.It has a separate quartz- controlled generator. Sets of lines for different matrices, each containing up to 40 elements, are held in the computer and called up by a simple command. Back- ground correction, inter-element correc- tion and standard additions are routine facilities, together with rapid qualitative analysis and semi-quantitative routines. Linton Instrumentation, Hysol, Har- low, Essex CM18 6QZ. Spectrophotometer The Shimadzu UV-160 is a compact double-beam. It takes only 25 s to scan its entire range of 1100-200 nm. Standard functions include quantitation by the least square calibration method using single Ultraviolet Scanning System The makers’ PU 8600 ultraviolet - visible spectrophotometer can be converted into a scanning system by using it in conjunc- tion with a BBC Micro. The software extends the PU 8600’s capabilities to include spectral display in colour, re- scaling and manipulation of data, first to fourth derivative, storage of spectral data, list out and screen-dump facilities and determination of Amax..Pye Unicam Ltd., York Street, Cam- bridge CB1 2PX. Spectrophotometer Accessories A range of accessories for the makers’ Response ultraviolet - visible instruments includes a rapid sampler for small sample analysis, a six-position Thermoset for prolonged temperature work and a gel scanner for a variety of gels and films. The accessories can be installed by the opera- tor and require no external cable connec- tions. The Response microprocessor con- trols all of the necessary functions, such as scan rates, temperature and sample return, and it can memorise calibration values for the temperature-dependent accessories if there is a power failure.Corning Ltd., Halstead, Essex C09 2DX. Data-Base for Infrared Spectrometry The Sadtler Standard Spectra library is now available in digitised form. Almost 100 000 spectra may be searched, and a wide range of sub-sets of the main library cover most industrial and academic appli- Shimadzu UV-160 spectrophotometer wavelength, two or three wavelength or derivative values, kinetic assay and multi- component analysis. The UV-160 can expand and compress spectra, peak pick, differentiate, smooth and commit spectra to data memory. Arithmetical calcula- tions between spectra are also possible. V. A. Howe and Co. Ltd., 12-14 St.Ann’s Crescent, London SW18 2LS. cations. Already usable with Bruker and Digilab Fourier transform infrared spec- trometers, the data base is also available on Perkin-Elmer’s 7000 Series data sta- tions and it is fully compatible with their SEARCH software. Heyden and Son Ltd., Spectrum House, Hillview Gardens, London NW4 2JQ.304 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 Gas Chromatograph The Model 3500 has been designed specif- ically for use with the more inert capillary fused silica columns. It incorporates the self-testing features of the makers’ Models 3300 and 3400 gas chromato- graphs and it offers electronic pressure read-out, thus allowing easy reproduction flows for split/splitless injection. It also features split flow read-out and column (calculated) flow read-out.Also offered is automatic column standby temperature, which eliminates daily flushing, and heated pneumatics, giving good retention time reproducibility. The 3500 is compat- ible with the makers’ 600 Series data systems for total automation. The mak- ers’ 8035 autosampler can accommodate all injection modes, including on-column capillary injection. Varian Associates Ltd., 24-28 Manor Road, Walton on Thames, Surrey. Thermal Conductivity Gas Chromatograph The Delsi Model 11 is a compact isother- mal instrument, which can be used on a bench or fitted to a wall. It is fitted with an 1/8 in injector as standard but it can be optionally fitted with manual or auto- matic gas sampling and column switching valves. It is intended for routine or control analyses.Dorand Electronics Ltd., Delsi Instru- ment Division, Allens Lane, Hamworthy, Poole, Dorset BH16 5DA. Columns for Liquid Chromatography Cartridge colums are available in a variety of column lengths, packed with CI8, C8 or silica gel, consisting of spherical 5-, 3- or irregular 10-pl particles. The replaceable part of the column, the cartridge, is a 316 stainless-steel tube packed with stationary phase. Also available are 6-pm columns for high speed amino acid analysis. An integral part of the makers’ amino acid analysis systems, they offer good resolu- tion and a sensitivity of less than 20 pmole. Complete separation of protein hydrolysates is possible in 30 min. Appli- cations include the routine analysis of meat hydrolysate, beer, orange juice and medical products, such as intravenous solution.Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Photoionisation Detector The HNU Model PI 52-02 will detail purgeable aromatics, such as benzene, chlorobenzene, ethyl benzene, toluene and xylenes in the presence of low relative molecular mass chlorinated hydrocar- bons. Adaptable to any chromatograph, it is up to 50 times more sensitive than the FID requirements for aromatics over a concentration range of 0.05-5.0 pg 1-1. Analysis Automation Ltd., Southfield House, Eynsham, Oxford OX8 1JD. Chromatography Fittings A range of British-made, stainless-steel, HPLC column end fittings is available. It covers fittings for 1/8, 1/4, 3/8 and 2 in column sizes and includes straight unions, nuts, ferrules and a stainless steel mesh or frit.A recent development is the Duo- socket, a system of stepped bores that makes a tube fitting equally suitable for joining by adhesives or soft soldering. Lo-melt 11, a solder - flux mixture that is applied in paste form, is also available. Lancashire Fittings Ltd., County Works, Claro Road, Harrogate, North Yorkshire HG1 4AF. Equipment for HPLC The Model 1025 HPLC gradient con- troller for binary elution gradients will form gradients in both high and low pressure mixing systems. A low pressure mixing module, the Model 1020, is avail- able as an accessory, working equally effectively with manual and automatic sample injection methods. The Model 1025 can fully define a profile, from a simple linear gradient to a complex curve or stepped gradient.Within each profile the user can nominate as many as 10 independent relay events to trigger exter- nal devices during the run. A total of 10 gradient profiles can be stored in RAM, which is protected against mains failure. Among the facilities is the capability to open out peaks for close examination or to flush them out by single keystroke. Real time profile editing allows the user to change a gradient profile and the auxiliary relay events without interrupting a run. A small printer is incorporated. Drew Scientific Ltd., 12 Barley Mow Passage, Chiswick, London W4 4PH. Liquid Handling Equipment The Amica system consists of an auto- sampler, a liquid processor, a microcom- puter, a printer and either a spectropho- tometer or a pH meter.It can be used for routine photometric measurements and for potentiometric and photometric titra- tions. The makers, Hamilton, have tested a number of applications and application notes are available. Among the determi- nations are those of phosphate, nitrate and ammonium. Hamilton have devel- oped a BASIC program for controlling the Amica A-5000 liquid processing unit. It is run on the EPSOM HX-20 computer and has a capacity of 20 methods. An impor- tant feature of the program is the capabil- ity for easy modification and extension of applications, e.g., for the connection of autosamplers and spectrophotometers. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. Automatic Titration A computer aided titrimeter system, CAT, offers five titration modes in addi- tion to a direct reading capability for pH, mV or activity.Three modes include fixed end-point, incremental and equilibrium titrations. Recorded and derivative titra- tion modes are also available and make use of the optional printer - plotter to display the titration graph. In addition to the five standard titration methods, 25 customer methods can also be stored. The controller can be interfaced with an elec- tronic balance. There is an optional rotary or linear multi-sampler and a data management system based on an Apple IIe computer has been introduced. Allied Instrumentation Laboratory Ltd. Moisture Determination The Coulomatic K-F titrimeter system is suitable for the determination of moisture in lubricants, fuels, solvents, pesticides, detergents, foodstuffs, pharmaceuticals, etc.Samples are injected into a reaction cell, where the exact amount of iodine required for the Karl Fischer reaction is generated electrolytically. The water con- tent is determined as a direct function ofANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 305 the amount of electrolyte current and consequently no standardisation is required. Correction for cell drift is auto- matic and the rate of compensatory titrant used is determined by continuous titration between samples. Allied Instrumentation Laboratory Ltd. Miniature Modules The 1000 Series LCD modules measure 60 x 38 x 21 mm. The 1008 Series module is suitable for building into new or existing equipment and can monitor either temperature (using type K thermo- couples or PtlOOO sensors) or processes on a 4-20 mA loop.Models 1008K and 1008Pt cover up to 700 "C, whilst the Model 1008 mA can be adjusted to any desired reading. Digitron Instrumentation Ltd., Mead Lane, Hertford, Hertfordshire SG13 7AW. Thermal Analysis Systems The makers' 7 Series system has been expanded by the addition of a fourth task and a new instrument module, the TMA 7 thermomechanical analyser, making pos- sible the control of up to three instru- ments or three calculations simul- taneously and in any combination at the same time as results are being plotted. The TADS Series thermal analysis system has also been expanded by the addition of a new DSC-4 Robotic System, which is compatible with new and exisiting DSC-4 differential scanning calorimeters. The DSC-4 Robotic System consists of a removable, 48-position sample carousel and a pneumatically controlled sampling arm which automatically selects a desired sample from the carousel, places it in the DSC-4 sample holder and closes the sample holder enclosure cover. The DSC experiment, which has been set up in the Robotic System software program on the thermal analysis data station (TADS), is then automatically performed. Perkin-Elmer Ltd., Post Office Lane , Beaconsfield, Buckinghamshire HP9 1QA. Organic Carbon Analyser The 01 Corporation Model 700 instru- ment features analysis below 10 p.p.b.on the standard instrument, a fully automatic operating sequence and automatic Sam- pling on all but the basic model. The Model 700 can handle samples with a high salt content without special reagents and high particulates without filtration.Options include: a solids by ampoule system, p.p.m. to 100% levels; silicon wafer contamination by wafer-TOC; an autosampler capable of handling 72 Sam- ples (septum piercing available); and mul- tiplexing for two or more streams. Centronic Sales Ltd., Centronic House, King Henry's Drive, New Addington, Croydon CR9 OBG. Ethylene Oxide Monitor The HNU Model 301 low level ethylene oxide monitor provides specific determi- nation of ethylene oxide in sterilisation and process areas to a detection limit of less than 20 p.p.b. It is a compact gas chromatograph with photoionisation detection and it provides an analysis in 120 s. Real-time concentrations are reported in p.p.m. and time-weighted averages are calculated.A multi-point option provides for 5 sample points, a calibration port, automatic calibration and an automatic zero. There are 2 programmable alarms set for each point. Analysis Automation Ltd., Southfield House, Eynsham, Oxford OX8 1JD. Analyser for Opaque Liquids and Slurries The TPA 202 attenuated total reflectance analyser is based on the reflectance of an infrared beam on to a crystal immersed in the liquid stream. It is being used to measure water in detergent, in oil, in diesel fuel, in LNG condensate and in various solvents, and to analyse the car- bon dioxide content of beer. It can also recognise samples such as opaque and soft solids and pastes. Sieger TPA Ltd., 34 Tresham Road, Orton Southgate, Peterborough PE2 OSE. Near Infrared Reflectance Analyser The InfraAlyzer 450 replaces the makers' InfraAlyzer 400 for all applications.Among the innovations are software faci- lities. Applications include analysis in feed compounding and flour milling, in dairies, in brewing, in the chemical and pharmaceutical industries and in food processing. Technicon Instruments Co. Ltd., Evans House, Hamilton Close, Basing- stoke, Hampshire RG21 2YE. Liquid Scintillation Cocktail A non-flammable cocktail, Safefluor, is a polyalkylbenzene-based solvent with a flash-point above 100 "C. It has a high loading capacity, requiring only 4-8 ml ml-1 of aqueous sample, and a high quench resistance. It is compatible with both glass and polyethylene vials and it is guaranteed for 2 years when stored away from direct sunlight at room temperature.May and Baker Ltd., Liverpool Road, Eccles, Manchester M30 7RT. Balance The AE200 analytical balance has a 205 g weighing range and a readability of 0.1 mg. Options make it possible to trans- fer data via RS232C, CL and IEEE 488 interfaces. Operated with a single control bar, it has an adjustable stability detector and a selectable integration time exten- sion, making possible adaptation to spe- cific operating conditions. The weighing chamber is accessible from 3 sides. Mettler Instrumente AG, 8606 Greifensee, Switzerland. Industrial Scale The Sauter El210 weighs 60 kg with 1 g accuracy. Its stainless-steel construction affords corrosion protection. Taring is by key. The El210 can be connected to a printer or computer and it can be used for absolute weighing, check weighing, com- pound or formula weighing or to measure slow mass changes.Mettler Instrumente AG, 8606 Griefensee, Switzerland. Microscope Stage A warm stage that can be fitted to almost any microscope is available. Consisting of the stage itself and a control box on which any temperature from ambient to 60 "C can be set, the unit is coated with ano- dised aluminium for high thermal conduc- tivity. A layer of transparent insulation helps to maintain a constant temperature over the stage. The set point can be adjusted to 0.1 "C and the temperature can be maintained to kO.l "C. Paar Scientific Ltd., 594 Kingston Road, Raynes Park, London SW20 8DN. Shaking Water-bath The bath is electronically controlled and has a mechanically driven shaking trolley.A transparent lid ensures temperature stability within k 0.1 "C up to 80 "C and it prevents evaporation loss. Temperature control is manual or automatic and the temperature is digitally displayed. A cut- out prevents overheating. The shaking speed is continuously adjustable in the range 10-150 strokes min-1 and the stroke length can be varied up to 50 mm. Tecator AB, Box 70, S-263 01 Hoga- nas, Sweden. Microgrinder The Braun Micro-Dismembrator, which is based on the ball mill principle, allows the preparation of homogeneous samples from inorganic materials and also from substances such as hair, skin tissue, liver, kidneys, cartilage and dental enamel. It can be used for contamination-free prep- arations in trace element analysis, dry or wet grinding, embrittling, etc.The vials in which the samples and grinding balls are oscillated are available in stainless steel or polyfluoroethylene. The balls are sup- plied in polyfluoroethylene coated steel,306 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 stainless steel, chromium steel, tungsten carbide and agate quartz. FT Scientific Instruments Ltd. , Station Drive, Bredon, Tewkesbury , Gloucester- shire GL20 7HH. Viscometer The AVS 440 can carry out viscosity measurements on both opaque and clear liquids. The sensors are completely encased in the glass housing and so hot and corrosive liquids can be handled. The whole cycle runs automatically and flow times of up to 9999.9 s can be automatic- ally measured to an accuracy of 0.01 s irrespective of capillary size and viscosity. Literature A catalogue describes the latest Polyvac range of direct reading optical emission spectrometers.Samples involving as many as 80 elements can be analysed by these instruments in seconds and the results displayed on a screen or in hard copy print-out . Entitled “Polyvac- Analysis Aid to Industry,” the publication discusses applications and excitation tech- niques. Hilger Analytical Ltd., Westwood, Margate, Kent CT9 4JL. A brochure gives details of the Herzog range of sample preparation equipment Schott A VS 440 viscometer After a programmed number of condi- tioning cycles the flow times are measured and stored, and the mean is calculated from a selected number of repeat measurements. The absolute or relative viscosity can also be determined from the viscosity constants and flow-through times stored in the memory.There is an RS232 interface. Schott Glass Ltd., Marketing Services, Drummond Road, Stafford ST16 3EL. Polyfluoroethylene Tubing Tubing made by Rariton of New Jersey, USA, is available in a dual construction, combining Teflon FEP and TFE. It can be heat-shrunk around components, cables, etc., to protect them from adverse condi- tions. This Dual Shrink tubing protects against heat (up to 450 OF), moisture, corrosion, shock, abrasion, etc., and it has good electrical properties. Zeus Industrial Products Inc., c/o Mal- colm Leybourne, Roggersdorfer Strasse 13, D-8150 Holzkirchen, West Germany. for use in X-ray spectrometry. bridge CB1 2PX. Pye Unicam Ltd., York Street, Cam- A publication describes the new Vega series of gas chromatographs.Emphasis is placed on the user friendly control unit, giving examples of displays from the unit’s video. A range of injectors, detectors and packed, capillary and wide-bore columns is described. Erba Science (UK) Ltd., Headlands Trading Estate, Swindon, Wiltshire SN2 6JQ. A brochure gives information on HPLC column systems, solvents and modifiers, standards and detection reagents. Special attention is given to traditionally difficult areas of analysis, such as high relative molecular mass biomolecules and car- bohydrates. Pierce (UK) Ltd., 36 Clifton Road, Cambridge CB1 4ZR. A booklet describing how ion chromato- graphy is being used to determine en- vironmentally critical compounds includes in its contents the analysis of drinking water, soil and industrial - domestic waste.Measurements of acid rain and other airborne pollutants are also given. The publication features 37 ion chromatograms. Dionex (UK) Ltd., Eelmoor Road, Farnborough, Hampshire GU14 7QN. Application information detailing operat- ing parameters and performance data is available on Dri-STAT and Liquid-STAT reagents, which give good results on the Technicon RA-1000 analyser and on the IL-Multistat from Instrumentation Lab- oratory. Beckman Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buck- inghamshire . Application and methodology sheets are available on Radiometer’s electrochem- ical instrumentation. Two of the most recent applications are for their RTS 822 titration system. One is for the determina- tion of available chlorine in hypochlorite solutions and the other is for the determi- nation of available oxygen in detergents. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. A leaflet describes the Model 3460 metals analyser for production control, and application summaries detail its perfor- mance in the analysis of irons, low alloy steels and high alloy steels. Each sum- mary illustrates the sample taking pro- cedure and provides specifics on sample preparation, instrument parameters and performance guarantees. Applied Research Laboratories, Bausch and Lomb (UK) Ltd., Wingate Road, Luton, Bedfordshire LU4 8PU. A leaflet describes the new 500 Series multi-meter temperature probes for read- ings of air, liquid or surface temperatures. Digitron Instrumentation Ltd. , Mead Lane, Hertford, Hertfordshire SG13 7AW. An application brochure discusses micro- biological procedures using membrane filters. Particular emphasis is placed on the bacteriological analysis of water and waste water. A Micro Filtration Systems general catalogue is also available. Uniscience Ltd., 12-14 St. Ann’s Cres- cent, Wandsworth, London SW18 2LS.

ISSN:0144-557X    

DOI:10.1039/AP9852200303

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 307 Conferences and Meetings Control and Instrumentation-The Changing Scene November 27-28, 1985, Harrogate The programme for this Institute of Measurement and Control symposium is virtually finalised. Over the two days seventeen papers will be presented in four sessions. Wednesday November 27, Morning Session “Optical Systems in Measurement”: Optical Systems in Pro- cess Measurement by R. J. Weir (Endress & Hauser); Fibre Optics in Physical and Chemical Sensors by D. C. Spooncer (UMIST); Optics in Engineering by D. J. Whitehouse (University of Warwick); Infrared Flame Monitoring for Multi- burner Installations by P. J. Webb (Land Combustion); The Development of On- line Measurement of Crystal Growth by Laser Diffraction by D.J. Brown and T. Gregory (University of Sheffield). After- noon Session “Innovation in Flow Measurement”: Pulse Signal Analysis- Opportunities for Flow Meter Enchance- ment by R. Fell (University of Bradford); Advances in Transit Time Ultrasonic Flow Meters by M. L. Sanderson (Univer- sity of Salford); Developments and Appli- cations in Cross-correlation by J. Coul- thard (Teesside Polytechnic); Flow Imag- ing by M. S. Beck (UMIST), R. G. Green (Bolton Institute of Higher Education), E. A. Hammer (Christian Michelsen Institute, Norway) and A. Plaskowski (UMIST). Thursday November 28, Morning Session “Batch Process Con- trol”: Review of the Use of Control and Computers in the Batch Process Sector of the Chemical Industry by R. Parakrama (Warren Spring Laboratory); Software for Batch Process Control by R.M. Henry (University of Bradford); Modell- ing Batch Chemical Processes-A Case Study by J. A. Wilson and W. Smith (University of Nottingham); Safety Aspects of Sequence Control by A. J. Margetts (Lihou Loss Prevention). After- noon Session “Robots in Batch Produc- tion and Analysis”: Laboratory Automa- tion-Analytical Sample Preparation by a speaker to be confirmed; Humans versus Robots by L. A. Gifford (University of Manchester); The Application of Indus- trial Robots to Laboratory Automation by G. Carter (Systems Control Ltd.); Two Case Studies: Robots in Textile Handling; A Sensor Guided Robot for Electronic Circuitry by K. Selke (University of Hull). Registration for periods as short as one session will be possible, thus allowing participants to have time to visit the C & I Northern Exhibition, which will be across the road from the conference on Novem- ber 26-28.Further details are available from The Institute of Measurement and Control, 87 Gower Street, London WClE 6AA. Fifth International Cadmium Conference to Examine Markets and Environmental Questions February 4-6, 1986, San Francisco, CA, USA Cadmium producers, industrial con- sumers and those who are working to ensure that cadmium is safely handled will all have a chance to come together when the Fifth International Cadmium Confer- ence convenes in San Francisco’s Fair- mont Hotel. The conference, which is jointly sponsored by the Cadmium Asso- ciation (London), the Cadmium Council (New York) and the International Lead Zinc Research Organization (New York) will explore such topics as cadmium supply and demand, the range of markets for cadmium and its products, cadmium’s indispensible role in industrial applica- tions, biological monitoring of cadmium levels in humans, cadmium in the environ- ment and health criteria and government actions involving cadmium.A special feature will be the Second International Nickel - Cadmium Battery Seminar, which will be held on Tuesday February 4 as part of the larger conference. The seminar will cover marketing, techno- logical and re-cycling aspects. For more details of the conference and advance programme contact S. A. His- cock or D. N. Wilson, Cadmium Associa- tion, 34 Berkeley Square, London W1X 6AJ. Materials Testing 86 Exhibition March 17-20, 1986, Birmingham This exhibition will be held at the National Exhibition Centre and spon- sored by the British Institute of Non- destructive Testing and the Society of Environmental Engineers.It will show developments in non-destructive and de- structive testing equipment and the advances in the associated systems, ancil- laries and test facilities. For further information contact Mack- Brooks Exhibitions Limited, 62 Victoria Street, St. Albans AL1 3XT. Trace Element Analytical Chemistry in Medicine and Biology April 21-23, 1986, Neuherberg, FRG The fourth international workshop on this subject will be held in the Gesellschaft fur Strahlen- und Umweltforschung and is intended to bring together analytical and biomedical specialists. The topics covered by the workshop will include bioavailabil- ity, speciation, parenteral nutrition, recommended dietary allowances, in- teractions and analytical techniques.For information contact Dr. Peter Schramel, Gesellschaft fur Strahlen- und Umweltforschung mbH, AG “Spurenelementanalytik,” Ingolstadter Landstrasse 1, D-8042 Neuherberg, FRG. Second International Symposium on Bio- logical Reference Materials April 24-25, 1986, Neuherberg, FRG This symposium will be held immediately after the workshop on Trace Element Analytical Chemistry in Medicine and Biology. As with the latter meeting, contributed papers are sought. For information on the meeting contact Dr. Markus Stoeppler, Institut fiir Ange- wandte Physikalische Chemie, Kernfor- schungsanlage Julich GmbH, Postfach 1913, D-5170 Julich 1, FRG.Surfex 86 May 14-15, 1986, Harrogate The northern sections of the Oil and Colour Chemists’ Association will organ- ise this exhibition for the surface coatings industry. The address for information is OCCA, Priory House, 967 Harrow Road, Wem- bley, Middlesex HA0 2SF. 1986 Hewlett-Packard Analytical Sym- posium June 23-27, 1986, Harrogate Following the success of the 1985 Analy- tical Symposium held in Stratford-upon- Avon, Hewlett-Packard Limited will hold their 1986 meeting at the Majestic Hotel, Harrogate. Distinguished speakers from Europe and the USA will present original work on the techniques and applications of ultraviolet - visible spectroscopy, gas and liquid chromatography, chromat- ography - mass spectrometry and labora- tory automation and information management.Delegates will be able to register for individual sessions as appro- priate. Further details can be obtained from Tina Mears, Hewlett-Packard Limited, Analytical Instrumentation Group, Miller House, The Ring, Bracknell, Berkshire RG12 1XN. Anal y t ik treffen 1986 September 15- 19,1986, Neu branden burg, DDR This meeting consists of Atomspektrosko- pie and IX CANAS, conferences on research an analytical applications of atomic spectroscopy and specifically analytical atomic spectroscopy, respec- tively. The conference languages will be German, English and Russian. The Iec- tures, posters and discussions will cover the theory and analytical applications ofANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 atomic absorption spectrometry, atomic emission spectrometry (arc, spark, laser, high frequency, microwave and glow dis- charge techniques), atomic fluorescence spectrometry and X-ray fluorescence spectrometry. For further information contact Doz. Dr. Sc. K. Dittrich, Karl-Marx- Universitat Leipzig, Sektion Chemie, DDR-7010 Leipzig, Talstrasse 35, Ger- man Democratic Republic.

ISSN:0144-557X    

DOI:10.1039/AP9852200307

出版商:RSC    

年代:1985

数据来源: RSC

摘要:

308 ANALYTICAL PROCEEDINGS, OCTOBER 1985, VOL 22 Courses Basic High-performance Liquid Chrom- atography November 11-13, 1985, London This course, which is organised by Chrompack UK Ltd., has been designed specifically for beginners with limited experience who wish to build on existing knowledge and increase their practical skills. The object of the course is to give students a basic knowledge of the theory and practice and manual skills by means of lectures and practical sessions. The fee for the course is f195 plus VAT. For further details of the course and the London venue, and for registration forms, please contact Chrompack UK Ltd., Unit 4, Indescon Court, Millhar- bour, London El4 9TN. Advanced High-Performance Liquid Chromatography November 18-20, 1985, London This course, which is again organised by Chrompack, covers both the theoretical and practical aspects of the latest develop- ments in HPLC. It is particularly suitable for those delegates who have attended the Basic HPLC Course (above) or for those who have previous experience in the subject. The fee for the course is f230 plus VAT. For further details of the course and the London venue, and for registra- tion forms, please contact Chrompack UK Ltd., Unit 4, Indescon Court, Mill- harbour, London El4 9TN.

ISSN:0144-557X    

DOI:10.1039/AP985220308a

出版商:RSC    

年代:1985

数据来源: RSC