ISSN:0144-557X    

DOI:10.1039/AP98825FX017

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

ANPRDI 25(5) 141-176 (1988) Proceedings of the Analytical Division of The Royal Society of Chemistry 141 Reports of Meetings 141 Obituaries 141 Analytical Divison Biennial Formal Dinner 142 AD Distinguished Service Awards 144 Analytical Viewpoint 'Use of Uranium and Thorium in Teaching and Research Experiments' by P. J. Potts and R. N. Thomas 'Use of the Beckman CALS System in Quality Control' by A. D. Henderson 'Training the Analyst-Industrial View' by J. Tillman 'What Can ACOL Do for You' by N. Chadwick, 6. R. Currell and J. W. James 'Novel Techniques for Purity Assessment by High-performance Liquid Chromato- graphy and Their Implications for Pharmacopoeia1 Use' by J. G. D. Marr, B. J. Clark 147 SUMMARIES OF PAPERS 147 Pharmaceuticals and Fine Chemicals 147 14% 149 150 154 155 157 158 159 160 162 163 and A.F. Fell 'Validation of Analytical Methods' by Michael Martin-Smith and David R. Rudd 'Stability Testing-the Practicalities' by A. J. West 'The Evolution of Methods for the Determination of Heavy Metals' by R. N. P. Farrow and G. F. Lewis 'The Future-Peptides and Proteins as Drugs' by S. S. Davis 'Regulatory and Technical Problems in the Control of Monoclonal Antibodies' by B. C. Lewis 'Applications of Robotics in the Pharmaceutical Laboratory' by A. N. Hale 'An HPLC Method for the Determination of 5-Hydroxymethyl Furfuraldehyde in Injections Containing Dextrose' by J. S. Howells, D. Johnston and P. R. Vojvodic 'An HPLC Method Employing Diode-array Detection for the Identification of Natural Plant Extracts Tolu Syrup and Wild Cherry Syrup in a Herbal Cough Remedy' by J. S. Howells and D. Johnston 165 Equipment News 169 Analytical Division Robert Boyle Medal in Analytical Chemistry 170 Publications Received 170 Conferences and Meetings 174 Courses 176 Analytical Division Diary Typeset and printed by Black Bear Press Limited, Cambridge, England May 1988 Analytical Proceedings CONTENTS

ISSN:0144-557X    

DOI:10.1039/AP98825BX019

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 141 Analytical Division Biennial Formal Dinner Following the AGM of the Division on RSC in Burlington House. After dinner, vice Awards to Dr. G. W. C. Milner and March 25th, 1988, the biennial formal which was preceded by the President’s Mr. D. M. Peake. dinner commemorating the foundation of reception, the President of the Division, The principal speaker was Mr. R. H. M. Symons, the Managing Director of BDH Ltd., who ended his speech by proposing the toast “The Analytical Divi- sion.” Mr. Squirrell replied on behalf of the Division and invited the members of the Divison to drink to “The Guests.” Mr. J. B. Aldred, the President of the Asso- ciation of Public Analysts, then re- ____^ _____-lll A t the President’s reception. (L-R): Mr.R. H . M . Symons, Mr. J . B. Aldred, Mrs. M . Squirrell, Mrs. C. Silverman and Mr. B. Silverman Mr. D. C. M . Squirrell and Professor Sir Jack Lewis the Society of Public Analysts (forerunner Mr. D. C. M. Squirrell, presented the of the AD) was held in the rooms of the fifteenth and sixteenth Distinguished Ser- (President of the Pharmaceutical Society) sponded on behalf of the guests. Other guests present included the President ofANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 Dr. G. W. C. Miher (R) receiving the fifteenth A D Distinguished Service Award from Mr. D. C. M . Squirrel1 Mr. D. M . Peake receiving the sixteenth A D DistingGished Service A ward from Mr. Squirrel1 The principal speaker at the Dinner, Mr. R. H. M . Syrnons (L-R) Mr. D. C. M . Squirrell, Professor Sir Jack Lewis and Mr. J . B. Aldred the Royal Society of Chemistry, Professor Pharmaceutical Society, Mr. B. Silver- Sir Jack Lewis, the President of the man, and Mrs. C. Silverman. vice Award recipients appear below. Biographies of the Distinguished Ser-

ISSN:0144-557X    

DOI:10.1039/AP988250141b

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 AD Distinguished Service Awards As was reported in the February issue (p. 36), the fifteenth and sixteenth Analytical Division Distinguished Service Awards have been awarded to Dr. G. W. C. Milner and Mr. D. M. Peake. George Milner was educated at Doncaster Grammar School from 1929 to 1936, and entered Sheffield University in 1936 to study science (chemistry, physics and mathematics). He took part in sports and represented both School and University at rugby football. After graduating with a First Class Honours BSc in 1939, and following the outbreak of war, he joined the staff of the Bragg Laboratory at the Naval Ordnance Inspection Laboratory in Sheffield. Dur- ing this period of his career he specialised in the application of absorptiometric and polarographic techniques to the analysis of metals and alloys under Mr.E. J. Vaughan. In 1946, Milner accepted the post ofANALYTICAL PROCEEDINGS. MAY 1988, VOL 25 143 Lecturer in Chemistry at the University of Hull, but returned to the Bragg Labora- tory in 1948 to work on analytical projects arising from the UK Atomic Energy Project. In 1951, he moved to the Ana- lytical Chemistry Group of the Chemistry Division of AERE, Harwell. He was appointed Group Leader of the Actinide Analysis Group of the Chemistry Division in 1963 and held this position until his retirement in 1983. The work of this Group covered all aspects of the ana- lytical chemistry of the actinide elements. Milner specialised in the analytical chem- istry problems connected with the appli- cation of nuclear safeguards on a national and international basis. This involved a close collaboration with the International Atomic Energy Agency in Vienna.Since 1983, he has been a consultant to the nuclear safeguards project in the UK. Milner was Honorary Treasurer of the Society for Analytical Chemistry for six years from 1967 and helped to build up the financial assets of the Society. He also played a leading role in the negotiations with the Chemical Society that resulted in a trial period of amalgamation that began in January, 1972. He was elected Presi- dent in 1973 and served in this post for 3 years so as to cover the first year of the Analytical Division following amalgama- tion. After 1976, Milner served on the Analytical Division Council for several years as a Past President and then for two years as an elected member. He had the responsibility of organising the work of the Analytical Chemistry Trust by serving as Chairman of the Trust Advisory Com- mittee for many years. A major aspect of the work involved the assessment of projects submitted for Studentships and Fellowships and making recommenda- tions to the Trustees.Since 1983, he has been an advisor to this committee. Cur- rently, he is Chairman of the Trustees to the Analytical Methods Trust Fund. Milner has published more than 100 papers on a range of analytical topics, and he was awarded the degree of DSc by Sheffield University in 1959 for his contri- butions to analytical chemistry. He is the author of a book entitled “Principles and Applications of Polarography and other Related Techniques” and co-author of “Coulometry in Analytical Chemistry.” In 1973, he was awarded the seventh Society for Analytical Chemistry Gold Medal for his published work in analytical chemistry.Milner acted as the Secretary of the Polarographic Discussion Panel set up by the Society in the early 1950s and eventu- ally became Chairman of the Special Techniques Group for 1959-60. He has served on the Council for the periods 1958-61, 1964-65 and 1967-82. For relaxation away from work, walk- ing and gardening are particular interests. Born in Wolverhampton, in 1923, Dudley Peake attended Queen Mary’s Grammar School, Walsall, and King Edward VI Grammar School, Nuneaton. On leaving school he made several unsuccessful attempts to obtain a position in a bank and then enquired at the Metals Division of ICI if any vacancies existed in their drawing office.He was offered a post as shift laboratory assistant in a furnace control laboratory which he accepted, a decision that he has never regretted. Following a transfer to the analytical section of the research department, day- release study at Birmingham Central Technical College brought a London external degree in chemistry and promo- tion to technical officer. Despite many offers of a wide variety of careers outside analytical chemistry, ranging from line-management to patent work, he remained in analytical chemistry until his retirement in 1985. During that period he acquired an extensive know- ledge of many widely differing fields of analysis and, in particular, the analysis of all types of metals and alloys, and was responsible for the development of a large number of analytical procedures, some of the more novel of which were published in the journals.He always claims that the two most interesting years in his life were those spent in the microanalysis labora- tory where he succeeded the legendary H. C. J. Saint. Much of the work involved the analysis of minute amounts of miscel- laneous materials, many so small that all operations had to be carried out under a microscope using a micro-manipulator. No two samples were the same and each offered a challenge to imagination and ingenuity. Then followed seven years in charge of the spectrographic section and finally, in 1971, after the decentralisation of the research department, he was appointed Chief Analyst of IMI Titan- ium.He was fortunate in working for many years under the late Dr. W. T. Elwell. who encouraged him to become involved in the work of the Society for Analytical Chemistry. It was, maintained Dr. Elwell, a duty to serve one’s professional body and a pleasure to share the company of analytical chemists who were a jolly fine lot. After 45 years of this association Dudley Peake would warmly endorse the latter view. In 1963 he first served on a Midlands Section committee and since then has served on the local committee as member, secretary, chairman and treasurer almost continuously until the present day. He was secretary of the committee which organised the very suc- cessful Birmingham International Sympo- sium in 1969, and was also a committee member of the Fourth SAC Conference, held in Birmingham in 1977.He has also been a member of the Atomic Spectro- scopy Group committee. For very many years he has had a particular interest in career advice for school children. This stems from both his personal lack of career awareness on leaving school and that of most of his friends. For this reason, over a period of more than 30 years, he has talked at schools, employment exchanges and at careers conventions on careers in che- mistry, and has tried, largely unsuccess- fully, to persuade school headmasters to devote more school time to careers talks and visits. He is still trying. In retirement he maintains contact with the “Analytical Club” through his posi- tion as the Honorary Treasurer of the Midlands Region. Some consultancy work keeps his mind occupied and any spare time outside conventional house- work and D.I.Y. is devoted to fishing, cooking, brewing beers and wines, visit- ing and entertaining his many friends and listening to and telling stories, some of them humorous.

ISSN:0144-557X    

DOI:10.1039/AP9882500142

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

143 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 Analytical Viewpoint The following is a member of 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 to 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 to receive manuscripts or to discuss outline ideas with prospective authors. Use of Uranium and Thorium in Teaching and Research Experiments P.J. Potts Department of Earth Sciences, The Open University, Milton Keynes, MK7 6AA R. N. Thomas Safety Service, University of East Anglia, Norwich, NR4 7TJ Traditionally, the use of uranium and, to a lesser extent, thorium reagents in teaching experiments has been subject to precautions appropriate to their chemical toxicity. It has, to date, rarely been necessary to take account of radiological considerations, these substances being regarded as laboratory chemicals. However, the Ionising Radiations Regulations, 1985, change this situation and demand that full account is taken of the radiation hazard associated with uranium and thorium materials in the design of experiments. Indeed, radiological protection procedures must be stringent as both of these elements decay by alpha emission.To set this hazard in context, data from Schedule 2 of the Ionising Radiations Regulations illustrates that the radiotoxicity of natural thorium is greater than equivalent activities of plutonium-239. Designers of experiments must now, therefore, justify the use of uranium or thorium materials on the basis of new criteria. (1) The use of uranium or thorium in an experiment can be justified only if it is not practicable to substitute non-radio- active materials. (2) A net benefit must accrue from the inclusion of uranium or thorium materials in any experiment. (3) The amounts of materials used in any experiment must be as low as is reasonably practicable. These notes contain suggestions for radiological protection and recommend the maximum masses of uranium and thorium derived from the Ionising Radiations Regulations, 1985, that should normally be used in experiments.The basic philosophy adopted is that conditions should never be created in a teaching laboratory that would require the creation of a controlled area or require students to be designated as classified persons. It is suggested that these conditions will also normally form the basis of research experiments. Guidance is also given on two other situations where radiological hazards may arise from uranium and thorium and their daughter isotopes: work with geological specimens and teaching experiments using “thoron” generators. Ionising Radiations Regulations-1985 The Ionising Radiations Regulations limit not only the activity of materials that may be used in an experiment without Copyright AURPO and the authors.detailed attention to radiological considerations, but also place other obligations on the designers and teachers of student experiments. (1) Students, aged 16 years and over, are regarded as employees of the host institution for the purposes of the Regulations. (2) Students between the ages of 16 and 17 years are limited to a maximum annual radiation dose of 15 mSv. Students aged 18 years and over are limited to maximum annual radiation dose of 50 mSv. The following notes assume that students in universities and polytechnics will fall into this latter category (i.e., aged 18 years and over). (3) Although it is expected that students will encounter very small doses in the course of teaching experiments, they must be fully briefed that any exposure to ionising radiations may involve a health risk.(4) Full responsibility rests on the host institution to provide adequate training in the hazards of ionising radiations and the specific manipulations required in the course of the experi- ment. This responsibility extends to ensuring that adequate protective clothing is provided. (5) Section 19 of the regulations requires records to be kept of the amount, location and disposal of compounds of uranium and thorium. Copies of the records must be kept for at least 2 years. It is suggested that for most purposes it would be more appropriate to describe the “amount” of these substances in terms of mass rather than activity. Specific Activities of Uranium and Thorium The data that follow have been selected for experiments using the following elements.Firstly, natural uranium of composi- tion 238U (99.3% natural abundance) in secular equilibrium with its daughter isotope 234U (0.0054%) and 235U (0.711°/0). The calculated specific activity of this material is 25 Bq mg-l. Secondly, natural thorium, of composition 2QTh (lOOo/O), in secular equilibrium with its daughter isotope 228Th and having a specific activity of 8 Bq mg-1. Uranium compounds supplied by leading chemical suppliers are likely to consist of “depleted” uranium in which the activities of 235U and 234U have been reduced by 40-60%. The equivalent specific activity of this depleted material is expected to be in the range 16 Bq mg-1. Due allowance may be made to the data listed in the following sections if depleted rather than natural uranium is to be used in experimental work. Through- out it is assumed that materials have been chemically purifiedANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 1-45 to remove activities due to other uranium or thorium daughter isotopes.Experiments Involving the Use of Closed Sources In these notes, closed sources of uranium or thorium are regarded as sources that would not be expected to give rise to any contamination in the course of normal manipulation. If there is a significant risk that the source might be dropped, containment (for example of uranium and thorium reagent powders) in simple glass bottles with a screw top should not be regarded as providing adequate security against the risk of contamination.In assessing what might be regarded as an acceptable dose to which a student might be exposed in the course of a teaching experiment, many institutions will already have their own agreed limits. However, the following considerations should be noted: (1) the Regulations require that all necessary steps are taken to restrict so far as is reasonably practicable the extent to which employees and other persons are exposed to ionising radiation; (2) where exposure of the hands is concerned, the Regulations require that the time averaged dose rate should not exceed 75 pSv h-1 outside a “controlled area”; (3) the International Commission on Radiological Protection recommends that for experiments undertaken by students under the age of 18 years, the dose rate at a distance of 10 cm should not exceed 10 ~ S V h-1.It is proposed, therefore, that the maximum mass of material that should be available to students as a closed source be such that the dose rate measured “at a few centimetres” from the source does not exceed 75 pGy h-1. In the absence of precise data, the approximate masses of metal that correspond to this limitation are 250 g of uranium and 100 g of thorium. In deriving these masses it is assumed that: (1) the activity arises essentially from gamma emissions alone, beta and alpha particles being absorbed within the source containment material; and (2) the source will always be handled with tongs or remote handling tools, never picked up directly by hand. If the source containment is insufficiently absorbing to shield the beta radiations, the mass of materials available to students must be more restrictive to compensate for the increased radiation dose.Preliminary measurements suggest that under these circumstances, the masses of uranium and thorium listed above should be further reduced by a factor of ten. Experiments Involving the Use of Open Sources If experiments make use of open sources of uranium or thorium (for example, solutions, or uncontained powdered reagents), it is important to minimise the risk of contamination by careful experimental design. The effectiveness of these measures (in minimising contamination) must be proven by regular use of a suitable contamination monitor. In some circumstances the most appropriate instrument will be an alpha monitor, as the background reading of these devices is essentially zero.However, users must be made aware that alpha particles have a low penetrating power and that anomalously low readings will be obtained if, for example, a spill of uranium or thorium solution is absorbed within a protective bench coating material. If experiments make use of powdered reagents or coloured solutions, a simple expedient that may be used in conjunction with instrumental contamination monitoring is to carry out such work on a white experimental tray and/or bench coating material. Some uranium reagents are strongly coloured and even small spillages of powder or solution can be detected visually against a suitable background surface more sensitively than with simple monitors. If there is likely to be any uncertainty in the interpretation of contamination monitor readings or if airborne contamination is possible but cannot be monitored satisfactorily, it will be necessary for the amounts of material used to be kept strictly within the numeric limits specified below to avoid the necessity of designating the laboratory as a Controlled Radiation Area.Uranium The amount of uranium reagent that complies with contamina- tion criteria depends on the chemical form (the “lung class”), the least soluble reagents suffering the greatest restriction because they are retained in the lungs for the longest period. The retention times in the pulmonary region of the lung are defined as follows: Lung class D Lung class W Lung class Y Retention half time Less than 10 d 10-100 d More than 100 d In a teaching experiment involving, for example, the manipula- tion of powdered reagents, the entire class should not normally have access to more than the following amounts in any laboratory.Lung class D:19.1 g of soluble uranium reagent [e.g., UF6, UOzF2, UO,(NO,),]; Lung class W:11.4 g of less soluble uranium reagent ( e . g . , UF4, UC14, UO,); Lung class Y:0.38 g of highly insoluble oxide (e.g., U02, U308). As an alternative, the experiment must be so designed that there is no reasonable possibility of uranium contamination levels exceed- ing 2 mg cm-2 averaged over 300 cm2 ( i . e . , 600 mg over 300 cm2). Thorium The maximum amount of thorium reagent to which the class has access should be limited to 0.086 g. If the experiment demands the use of greater weights of reagent, experimental procedures must be designed such that there is no reasonable possibility of thorium contamination levels exceeding 0.84 mg cm-2 averaged over 300 cm2 ( i .e . , 252 mg over 300 cm2). In deriving these data, it has been assumed that reagents are sufficiently coarsely ground to prevent the airborne contamina- tion limit (uranium, 0.2 Bq m-3; thorium, 0.01 Bq m-3) ever being reached. If there is a risk of airborne contamination, then adequate facilities ( e . g . , a glove box) must be provided. Such considerations are particularly important with thorium since as little as 1 pg of finely divided thorium per cubic metre of air requires the designation of a controlled area. It is expected that experiments involving the use of uranium or thorium in solution form will conform to the limits outlined above provided concentrations are restricted to 1 mg ml-1 and normal solution handling techniques are employed.In such work mouth pipettes must never be made available to students. In deriving these limits it is assumed that students will be required to wear a lab coat and disposable gloves whenever handling uranium or thorium reagents of any mass and that the limitations on the mass of uranium and thorium available apply to the entire laboratory in which such experiments are carried out, not an individual bench. Although the above limits are considered to be appropriate for first-degree course students in universities and poly- technics, it should be noted that the International Commission on Radiological Protection recommends that for students under the age of 18 years, no more than 50 Bq ( 5 mg) of natural uranium and 5 Bq (1 mg) of natural thorium should be used for separate teaching exercises.Work with Geological Specimens A report from the National Radiological Protection Board (NRPB-R131: 1983) deals with the possible radiation hazards to collectors of geological specimens containing natural radio- activity. Unlike laboratory reagents that have undergone chemical146 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 purification, these specimens will also contain activities of daughter isotopes which are likely to be in secular equilibrium with parent 23W, 235U or 232Th. These daughters will therefore contribute substantial additional activity to the sample.The author of the NRPB report assumed that a typical collection of minerals includes about 1% of samples that contain significant amounts of radioactivity. Of these, a proportion may be “high quality” specimens that have been obtained from specialist suppliers. It was assumed that if 100 hours per year are spent handling the collection, the average annual handling time of radioactive specimens will be 1 h. The report concluded therefore that radiation dose rates, radon exhalation rates and amounts of loose contamination from uranium minerals can be sufficiently high to warrant considerations of the hazards associated with their collection. However, if realistic assumptions are made about collecting and handling habits (as listed above) annual doses arising from collecting are likely to amount to only 3-5% of the level appropriate for limiting radiation exposure to members of the general public.The conclusion assumes only limited handling of “high quality” samples. Sensible precautions applicable to collecting, handling and curating of uranium or thorium minerals include the following. (1) Wear disposable gloves, wash hands after handling samples. (2) Do not store samples in an occupied area (to minimise inhalation of radon decay products). (3) Extreme caution must be taken should it be necessary to grind such samples to a fine powder prior to chemical analysis. If possible, samples should be kept wet during the grinding processes. If dry grinding is necessary, grinding apparatus should be fitted with an effective air - dust extraction system.It is recommended that the extraction efficiency of such equip- ment should be tested by direct measurement of airborne contamination levels. Mineral Separation One unusual aspect of uranium - thorium geochemistry is that these elements tend to concentrate in minor phase mineral grains in some rock types ( e . g . , granites). If work involves separating these minerals, especially zircon and rare earth element grains, from matrix phases, enhanced activities of uranium, thorium and daughter isotopes will be encountered compared with bulk specimens. In these circumstances, the legal obligations of the Ionising Radiations Regulations may apply, even though specific activities fall below the threshold of 100 Bq g-1 on which legal definition of a radioactive substance is normally based.Typical activities reported by Dixon (NRPB-R143) found in these minerals are as shown in Table 1. Use of Thoron Generators The release of 220Rn (“thoron”) gas from thorium compounds has been widely used to provide a convenient source of short-lived activity, especially in undergraduate and secondary school demonstrations of alpha particle tracks in cloud chambers. Apparatus suppliers (e.g. , Griffin) offer flexible plastic squeeze-bottles which contain approximately 25 g of thorium hydroxide. By squeezing the container, a quantity of air - gas mixture can be ejected from the space above the solid. A simple cloth filter is incorporated to discourage the release of powder. (Older devices supplied by other manufacturers do not incorporate this rudimentary safeguard.) Table 1.Activities of various minerals Chemical Mineral formula Bastnaesite CaFCO, Baddeleyite ZrOz Ilmenite FeTi03 Phosphate rock CaS(PO4),(0H,F,C1) Pyrochlore NaCaNb,O,F Zircon ZrSi04 (apatite) Principle source of activity Th U Th U Th Th Typic a 1 specific activity/ 5 18 1 3 Bq g-’ 70 8 A thoron generator of the kind described above will, in the absence of significant leakage, contain about 100 kBq of 220Rn in equilibrium with the thorium hydroxide. If part of this 220Rn is puffed out into the room air, it will decay with a half-life of 52 s into daughters which are also radioactive and have somewhat longer half-lives. The ICRP recommendation for the Annual Limit on Intake for 22ORn daughters, in terms of equilibrium equivalent radon activity, is 800 kBq.Making reasonable (but pessimistic) assumptions, it is unlikely that the intake resulting from a single “puff” of the thoron generator in a badly ventilated small laboratory would be greater than about 1 kBq. Thus, occasional use of these devices is unlikely to be a significant radiological risk. A greater risk might be caused by the contamination which could result from ineffective filtration of finely divided thorium hydroxide powder, and this should be taken into account in making these devices available to students. This note forms AURPO Guidance Note No. 2 and it was originally produced for the Association of University Radia- tion Protection Officers. The authors are grateful to the many members of the AURPO who offered constructive comments on earlier version of these notes. They are particularly grateful to Trevor Moseley, Donald Hughes and Keith Bowker for supplying them with additional information for the final draft. Bibliography “The Ionising Radiations Regulations 1985,” SI 1985, No. 1333, HM Stationery Office, London. “Protection against Ionising Radiation in the Teaching of Science: International Commission on Radiation Protection Publication 36,” Ann. ICRP, 1983, 10, No. 1. Dixon, D. W., “Radiation Hazards to Collectors of Geological Specimens Containing Natural Radioactivity,” NRPB Report R131, HM Stationery Office, London, 1983. “Limits for Inhalation of Radon Daughters by Workers: International Commission on Radiation Protection Publication 32,” Ann. ICRP, 1981, 6, No. 1. Dixon, D. W., “Hazard Assessment of Work with Ores Containing Elevated Levels of Natural Radioactivity,” NRPB Report R143, HM Stationery Office, 1984.

ISSN:0144-557X    

DOI:10.1039/AP9882500144

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 Pharmaceuticals and Fine Chemicals 147 The following are summaries of twelve of the papers presented at the Analytical Symposium at the RSC Autumn Meeting, held on September 22nd-24thI 1987, at the University of Nottingham. Use of the Beckman CALS System in Quality Control A. D. Henderson Finished Products Laboratory, Smith Kline & French Laboratories Limited, Welwyn Garden City, Hertfordshire In October 1984 we installed the Beckman Laboratory Management System in our Analytical Laboratories. The Beckman software runs on the laboratories’ existing Hewlett- Packard hardware. The objective was to install a flexible system to be shared by both Quality Control and Development Analytical laboratories. Our prime objective in the QC laboratory was to supply information more quickly, avoiding delays to the manufacturing and production lines, whereas a product stability package was seen as a major advantage to the Development laboratory.Both laboratories were also looking for simplified procedural control and to improve their ability to meet the requirements of good laboratory practice. Why We Purchased the Beckman CALS System In 1984 we chose to install the “Computer Automated Laboratory System” (CALS) because of the following points: (a) the system would collect data from our existing chromato- graphic instruments, data reduce and carry out laboratory management functions; (b) the software was user friendly; (c) the system had satisfied the FDA in terms of its compliance to good laboratory practice; (d) there were a number of phar- maceutical installations in the USA; (e) the software would run on our existing HP hardware; and (f) Beckman had experience in interfacing a wide spectrum of instruments to their system.Hardware and Software Our present Hewlett-Packard hardware consists of the follow- ing: (a) computer, HP1000, 21 MXE with 2 Mbytes of fast memory; (b) discs, HP7906, 20 Mbytes (“safeguard” mirror files), and HP7914, 130 Mbytes Winchester; (c) tape drive, HP7970E, 9 track, 1600 BPI; (d) multiplexers: two Beckman BMUX chassis; (e) terminals, 25 (4 colour, 18 graphics); (f) high-grade printer/plotters, 5; (g) instrument loops, 3; and (h) instruments, 28 HPLCs, 2 GLCs, 1 AAII and 2 UVs. Two Beckman hardware installations were made just prior to the implementation of the CALS software: (a) a buffered multiplexer (BMUX) and (b) a Beckman Digimetry Loop.The CALS software was installed in October 1984. The HPlOOO computer, except for the RTE-VI (Real Time Executive) software now operates exclusively with Beckman software. Operation The first month after installation was spent familiarising ourselves with the data collection and reduction software. This involved setting up chromatographic integration methods by means of the graphic methods development package called GMD. Meanwhile, the Laboratory Manager software was customised to suit the three laboratories. This we decided could best be done by dividing the data base into three groups: Group 1, Finished Products Laboratory, QC; Group 2, Raw Materials Laboratory, QC; and Group 3, Analytical Develop- ment Laboratory.At a later stage we could add further groups, e.g., Group 4, Microbiology; Group 5 , Commercial Stability; and Group 6, Inspection Control. During December 1984 the QC laboratory managers fam- iliarised themselves with updating the “Dictionaries,” a neces- sary step prior to the booking in of any new sample types: Dictionary Contents 1. Identification 2. Test User passwords, capability levels, book numbers, etc. All tests used by a particular “group” and details of the data which each test will pass to the data base. Calculations used by the tests. Record of tests to be applied to a sample type; can include the product specification limits. Retrieval and report procedures. 3. Calculation 4. Specification 5.Data base We found that Dictionaries 2, 3 and 4 could be easily maintained by the Laboratory Managers. For security pur- poses, l was to be controlled by the Laboratory Systems Manager and during the initial stages 5 would also be left to the Systems Manager. We validated the accuracy of retrieved data and from the beginning of January 1985 the QC laboratories decided to use the system on a number of raw materials and products. The following functions were to be used: 1. Login. 2. Testing. 3. Validation. 4. Approval. 5. Computer generation of analytical report. 6. Other data base retrievals. Samples were logged in using their SK&F inventory codes as the specification reference. The existing paper system was to be continued for the other products.We had decided that the rate of transfer to the computer system would depend on how effectively we carried out “on the job” training and how busy the laboratories were. In July 1985 the Analytical Development laboratory started to use the labmanager to log in all their samples. Applications Since installing the system we have found that we have made full use of the data base in the following applications: 1. SK&F Analytical Reports and Certificates of Analysis.ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 148 2. 3. 4. 5 . Lists. Summary reports. Matrix results reports. Trend analysis graphs. There are also specific examples where we have obtained benefits from the system: (a) Sample prioritisation by means of automatically generated sample lists has greatly improved our sample management in the QC laboratories.This has replaced the previous manual system where the laboratory was very dependent on information from a production planning depart- ment. (b) Reference sample data can be stored on the system and obtain all the benefits of the audit trail facilities. This is particularly useful for standards that require re-testing when outside the review date. Present Benefits The following four benefits have been achieved: (1) computer printout of analytical reports; (2) progress reports and screen enquiries; (3) procedural control and GMP audit; and (4) flexible system. With our major products we have found a time saving due to the benefits of 1 and 2. However, for our minor products the time saving has been minimal owing to the extra time required for staff training. There is, however, the advantage of having a computer-printed analytical report and the improved good laboratory practices.We have also found that now most of our sample types are on the computer we can benefit from a complete data base. The system works within our three laboratories. In 1987 we implemented two further Groups, i. e., Group 4, microbiology, and Group 5 , Commercial Stability, and implementation of Group 6, Inspection Control, was planned for late 1987. To make full use of these groups, we may have to purchase more computing power. Future Plans 1. Data base. With a computer data base it will be possible to produce yearly reports and reviews more easily. Comparative studies, for instance product stability, enhances the system’s potential for pharmaceutical development.2. Automatic results. The use of bar code and bar code readers will allow the automatic input of data such as weights. 3. Paperless system. By networking with other departments, our analytical results can be available throughout the company. The Beckman CALS Executive Labmanager, for IBM main- frame computers, should allow automatic linkage with our company mainframe. 4. Live system. Improvements are made to the system by means of a “wish” list. There is also an active USA and European users group where applications and problems can be discussed. Conclusions The Beckman system is a flexible working system. We have found through our use over the past 2Y2 years that it will control our laboratory information and give us an efficient expandable system.It also gives us the improved GLPs that are necessary in a pharmaceutical laboratory. Training the Analyst-Industrial View J. Tillman Fisons DIG, Pharmaceutical Division, R & D Laboratories, Bakewell Road, Loughborough, Leicestershire LE77 ORH. People are the most important asset of any company. In the analytical laboratory, the training of the analytical chemist must be high on the list of priorities of any manager. The following comments on training are personal ones based on experience in the development environment of the phar- maceutical industry. These views are based on a simple interpretation of the term “analytical chemist.” This descrip- tion has two parts: (a) Analyst: a person who can answer the questions: “What is in a matrix?” (qualitative analysis) and “How much is in a matrix?” (quantitative analysis).(b) Chemist: a person with a sound knowledge of chemistry (physical, inorganic and organic) and who can make things happen by the use of this knowledge. Hence an analytical chemist is a person who can use this chemical knowledge and the chemical properties of molecules to attain the objectives of qualitative and quantitative analysis. From this simple definition it is obvious that there are two areas of training and knowledge required-chemistry and analysis. Analysis requires training in the application of chemical analysis and in the large number of instrumental techniques available for quantitative and qualitative work. The principles of these techniques, and the advantages and disadvantages, must be clearly understood. In more recent years a knowledge and understanding of computers and computing has also been required.Thus, I believe that “analysis” requires as much understanding, training and experience as that required of a basic chemical qualification. With this thought, the training of an analytical chemist can be considered to lie in two main areas, as follows. Academia Without doubt the responsibility for providing a sound chemical background lies with academia. The only way of obtaining this is through a good chemistry degree at a university or polytechnic. In my view the burden of chemical education is such that there is insufficient time for academia to cover more than the principles of instrumental techniques at degree level.I believe that at undergraduate level the emphasis should be on chemical analysis. By this I mean the so-called “classical analysis.” This term is often used in a derogatory manner as “old-fashioned” analysis. However, I believe that it is still an interesting and useful way to correlate chemical principles and reaction mechanisms in a practical manner. Practical instrumental analysis should be left to postgraduate level, specialist short courses and to industry. This view is based on interview experiences with new graduates where two situations often arise. (1) The interviewee who claims experience in the analysis of compound X . On being ques- tioned, the interviewee does not even know the structure of compound X . In my view this knowledge of structure and the chemical properties of a compound is essential in order to be able to decide on any analytical approach, and should be the starting point of any graduate-level approach to solving an analytical problem.(2) The interviewee who claims experience of a certain technique, e.g., GLC. On enquiry it turns out that he has followed one prepared laboratory practical experiment. He does not know why GLC is the preferred technique, why a certain column was chosen, why a certain elution order was obtained or how the experimental conditions were arrived at. He has behaved solely as a technician.ANALYTICAL PROCEEDINGS, MAY 1988, VoL 25 149 Both of these above examples illustrate what I term the “black box syndrome,” that is, the following of a procedure without adequate knowledge and accepting results without question.This problem has increased over recent years with the increasing sophistication of analytical instruments. A printed output from an integrator is often accepted as valid without question. The analyst must be trained to look at chromatograms before accepting an integrator figure. Instru- ment manufacturers could help in this respect by marketing a range of simple, basic equipment for teaching purposes to illustrate principles. From the above comments it is easy to appreciate why our recruitment policy has changed, so that our preference now is to take on graduates with a good chemistry degree and probably little practical experience in instrumental analysis. The latter should be left to industry.Industry All analytical results are used to produce data on which a decision will be made. It is important, therefore, that these results are valid and meaningful. There is often also a time constraint. The analyst must therefore be trained to consider the most effective and appropriate technique to solve the problem in hand. In other words, he must be trained to think! Formal training in industry falls in two broad categories: (1) Outside training. That is, the attendance at specialist short courses on techniques and also one-day meetings and confer- ences. It is on such occasions that the analyst can exchange views with his peers in both industry and academia and keep in touch with current techniques, philosophies, etc. (2) In-house training.This can be both managerial or technical. In many laboratories a formal technical training programme can be organised, which can be based on the use of specific techniques or equipment or on the analysis of sample types. In all instances records should be kept to show that the analyst is capable of producing valid results. Final Thoughts Academia and industry provide the knowledge and the tools. It is then the responsibility of the analyst to use these to the best of his ability. It is important that the environment within the laboratory encourages this professional attitude. There are three areas that the analytical chemist can consider in the development of this professionalism, as follows. Relationship with Customer It is easy for the analytical group to be looked upon as a service department, simply present to produce results.The analyst must avoid this situation by establishing a firm and confident relationship with his customer. He must train himself to ask such questions as, “What is the problem?,” “Why do you want this analysis?,” “When do you want the results?,” “How accurate do you need the results?,” etc. It is only then that he can make a positive contribution to the customer’s problem and earn his respect. Above all, he must meet any commit- ments he makes. Analysis of the Problem Only when the problem is fully understood can the analyst decide which is the best approach. He must appreciate whether a highly accurate result is necessary or whether a simple yes or no answer is required. Very often, an approximate result obtained rapidly is more important than a very precise result which may take days to obtain.This requires a knowledge of a wide range of techniques, so that the most appropriate may be chosen. Confidence in Results Having confidence in a result is most important. If a sample is examined and found to fail the specification or to be unsatisfactory in any way, the first response of the customer will be, “How much can I trust your result?” This is only natural! The analyst must be able to respond to this-he is the best person to appreciate the problems of sampling, sample preparation and analyte measurement. Therefore, he is the only person capable of assessing the reliability of his data and interpreting the figures. This confidence can only be gained by critical examination of his procedures and subjecting his methods to a validation programme.The object of this is to be able to quantify the degree of reliability. Parameters such as precision, accuracy, specificity and linearity should all form part of this validation programme. What Can ACOL Do for You? N. Chadwick, B. R. Currell and J. W. James Thames Polytechnic, Woolwich, London SE 18 6PF What is ACOL? It can be a bridge convention, it can be a small village in the North East corner of Kent but in our context it is an open learning system in analytical chemistry of benefit to learners, employers and academe alike. The system relies on 30 open learning texts supported by counselling, tutorial and practical facilities from 44 ACOL Centres. What Can ACOL Do for Learners? It is useful to technicians already working in laboratories who wish to continue their education towards a formal qualifica- tion, or who wish to extend their knowledge of specific analytical techniques. The Royal Society of Chemistry recog- nises the use of ACOL towards the Certificate of Applied Chemistry, whilst the Business and Technician Education Council (BTEC) is planning to validate Certificates of Achievement and subsequently Diplomas in Continuing Edu- cation based on the ACOL system.It is useful to graduate chemists wishing to specialise in analytical chemistry after their first degree or to others finding themselves inadequately informed about everyday analytical techniques with which they have to grapple. Similarly, it is useful to professionals to up-date themselves on more modern techniques which they find creeping into their job or possibly to help cope with a mid-career change of direction.It is useful to scientists in disciplines other than chemistry who are faced with using or understanding the results from a specific analytical technique, particularly to the biologist, to environmental health officers and to health and safety execu- tives. Finally, it is useful to school teachers so they may translate the newer techniques to sixth-form students. Hence it is useful for many types and classes of people. But how does ACOL specifically help these various “learners”? To start with, as there are no lectures to attend, the learner can work at his or her own pace from the open learning texts that are provided, and soon from computer-aided learning150 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 materials, wherever he or she pleases, be this at home or on an oil rig in the North Sea (yes, we do have an ACOL student on an oil rig in the North Sea!).The student can choose what to study; naturally it would not be sensible for a student to embark on an ACOL course without some knowledge of chemistry, at least to A level if not preferably to a higher level. Counselling of students with regard to what is best for them can be obtained at ACOL Centres which are situated in 44 polytechnics and colleges throughout England, Scotland and Wales and more recently in Hong Kong and Alexandria. If a student is looking to improve his or her qualifications then clearly he or she has to satisfy existing examining boards with regard to a balanced course in analytical chemistry.Such a course would need to address both the basics and specific techniques. For those wishing to polish up on specific techniques, however, as they might previously have done by attending a short course, it can now be done the ACOL way. There is no need to wait for the next short course, which might well come at some inconvenient time. Many potential learners will be skilled practitioners or will be working in laboratories and will not need to be reliant on the practical facilities offered at ACOL Centres. They may still, however, want to make use of the tutorial facilities also offered at ACOL Centres, perhaps in a distant way by telephone, by exchange of tapes or, if they so wish, in a face-to-face manner.There are many motivations for the learner to improve his or her profile and qualifications which might not fit the plans of the present employer but would fit him or her for a more senior job elsewhere. The ACOL way means that the student can train independently of the employer, without the need for day release or other facilities. What Can ACOL Do for an Employer? If ACOL is so attractive for learners, what can it do for employers? ACOL and other open learning schemes provide an opportunity for employers to revolutionise their training programmes and to arrive at a much better trained workforce. It can be more cost efficient, it can be more cost effective and can forge links with the academic world. It can be more cost efficient because the organisation does not lose the services of its workforce for periods in the region of 15% of their available work time.How many training budgets show as a cost the number of days spent training multiplied by the day-man cost? More cost effective training can be achieved through tailored training. Over the last 3 years industry has sometimes said to us about our material, “fine for the basics, but we want our technicians to have more than that.” Of course, it is true that each company has its own chemicals, its own products and its own processes, all of which demand the exploitation, often in sophisticated ways, of the basics in ACOL. But truly, industry is reticent to define its own specific needs so that we can meet them in our texts.However, if ACOL is the chosen training route and if industry and the academics in our centres can get together, then the more sophisticated needs of the company can be met through the tutorial sessions. Tutorials can be tailored and devoted to case studies and problem solving; what better case studies than those related to the employers’ needs? The establishment of these special requirements can then be reflected back into future ACOL texts. It is hoped that it is not a too imaginative leap to think that the local ACOL Centre tutors can provide tutorials of the type envisaged for students on ACOL courses in industry’s labora- tories, either during work time or immediately afterwards. Employers should also be aware of the greater flexibility planned by the Council for National Academic Awards (CNAA) in future degree courses by credit accumulation and transfer. Using the greater range of open learning materials now available can lead to a much better qualified workforce.The combination of Open University material and ACOL could lead to a really formidable degree. What Can ACOL Do for the Academic World? It provides a whole raft of students not currently available to them, for example those to whom day release is not possible, those not able to attend short coutses at specific times and to those professionals who will not sign up for up-dating if it involves lengthy lecture hours at a teaching institution. The use of ACOL material can lighten the lecture load, thus providing more time for lecturers to spend on tutorials, which many find more stimulating than the lecture situation.Time is also available to really get to know local industry’s require- ments for tailored tutorials, hence improving the training role of the polytechnic or college. Novel Techniques for Purity Assessment by High-performance Liquid Chromatography and Their Implications for Pharmacopoeia1 Use J. G. D. Marr," B. J. Clark and A. F. Fell Department of Pharmaceutical Chemistry, University of Bradford, Bradford, West Yorkshire, BD7 I DP One of the major problems currently facing the pharmaceutical analyst in using high-performance liquid chromatography (HPLC) is the assessment of chromatographic peak purity. A great deal of time and effort has been spent on developing both qualitative and quantitative methods that address this prob- lem.Peak purity, expressed as the absence of co-eluting components (impurities), is an abstract concept and there- fore, as such, not measurable directly.' The analyst can only test for similarity of a sample to a standard, or detect the presence of co-eluents, thus inferring purity from the results. Detection in HPLC has historically been a univariate process involving detector response and time. This may be satisfactory for separating and measuring secondary peaks from the primary analytes. However, in order to investigate the degree of impurity of each individual peak, a third dimension of data is required. With ultraviolet - visible detection this * To whom correspondence should be addressed. Theophylline 0 220 240 260 280 300 320 3 Wavelengthinm 0 Fig.1. Normalised apical spectra of theophylline (52.51 pg ml-1) and p-xanthine (52.5 pg ml-1). r = 0.9947. For chromatographic condi- tions, see textANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 151 necessitates monitoring at two or more wavelengths, which conceptually has led to the development of three different types of multi-channel detector. The differences relate pri- marily to the detection system employed and these tend to be based on either a photomultiplier tube coupled to an oscillating grating or mirr0r~2.3 a vidicon tube4 or a linear photodiode array (LDA).s The functionality of the last type of detector is often determined by the degree of computer involvement rather than by the LDA per se. Indeed, by a judicious combination of computation and the number of elements in the LDA, two distinct groups of LDA-based detectors have arisen.Group 1 (high-resolution detectors) permit the acquisition of absorbance data across the full wavelength range of interest throughout the chromatography (spectrochromatographic data); Group 2 (moderate resolution detectors) permit the acquisition of simultaneous chromatograms together with a limited number of spectra. The amount of information therefore available from each of the two groups of detectors will differ, having a significant bearing on the methods used for chromatographic peak purity assessment I 390 a E . c.' 1 0) a, r Y m a .- 0 0.710 0.530 0.600 d 0.550 0.200 i? 0.1 60 A - - - 10.552.5 0 10 20 30 40 50 pXanthine in mixture with theophylline (52.51 pg rnl-l), % Fig.2. Comparison of the results obtained by various methods generally applied for assessing chromatographic peak purity, using solutions of p-xanthine alone, or in mixtures with a constant background concentration of theophylline (R, = 0.28), and monitoring the elution profile at 220 k 2nm. A, Width at half-height; B, peak symmetry; C, peak apex absorbance ratio obtained between 220 and 268 nm; and D, peak height. For chromatographic conditions, see text The methods which have been investigated in this work include those which were available as part of the commercial software package for the LDA detector and some in-house software initially developed to run on a Group 1 instrument, but which could be easily adapted for a Group 2 detector.The HPLC assay of theophylline in clinical samples is often complicated by the presence of caffeine and paraxanthine, one of its major metabolites.6 These components generally result from the intake of the beverages coffee and tea, which can lead to significant physiological base-line levels. Chromatographic- ally, separation of the two isomers theophylline and paraxan- thine can often prove difficult, especially if levels of other xanthines are also being monitored,7 or if a short analysis time is required. In the latter instance, selectivity has been found to be highly sensitive to small changes in mobile phase composi- tion.8 Consequently, it appears that the interference of paraxanthine in theophylline HPLC assays may occur more often than is realised. This could be expected to have a significant effect on the clinical management of patients, as theophylline has a relatively narrow therapeutic range.In the light of these observations a programme was set up, based on this system, to challenge the methods available for assessing the purity of the chromatographic peaks. Experimental Reagents and Materials A 20 mM solution of sodium acetate (AnalaR grade, BDH, Poole, Dorset) of pH 5 was prepared using glass-distilled water. Acetonitrile (HPLC S grade) and methanol (HPLC grade) (Rathburn Chemicals, Walkerburn) were used as received. The mobile phases were filtered through a 0.45-vm Millipore filter and degassed under vacuum in an ultrasonic bath for 10 min. Pure and binary solutions of theophylline and paraxanthine (Sigma Chemical, Poole, Dorset) were prepared using aqueous methanol.3.50 3.60 3.70 3.80 3.90 4.00 4.10 4.20 4.30 4.40 4.50 Timeim in Fig. 3. Comparison of the throughout-out peak absorbance ratio (Cheng amendment) obtained for a mixture of p-xanthine (52.5 pg ml-1) and theophylline (52.51 pg ml-l), R, = 0.28, showing the dependence of the results on the wavelengths chosen. (a) Elution profile at 240 nm; (b) absorbance ratio, 268/240 nrn, mean value = 3.64, RSD = 2.4'/0, 0% of points exceeded +lo% of mean value; and (c) absorbance ratio 284/240 nm, mean value = 1.45, RSD = 7.4%0, 10% of points exceeded t10% of mean value Equipment and Methods The modular chromatographic system consisted of an LDC 3000 pump [LDC (UK), Stone, Staffordshire] and a Rheodyne Model 7125 injection valve, (Rheodyne, Berkeley, CA, USA), provided with a 5O-pl loop, connected to a Radialpak Novapak CIS column held in an RCM-100 module (Millipore, Waters Chromatography Division, Edinburgh, UK).An HP1040M LDA detector (Hewlett-Packard, Waldbronn, FRG) fitted152 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 with a 4 . 5 ~ 1 flow cell was utilised with a spectral resolution of 2 nm per diode in the range 200-350 nm. The detector was connected by an HP-IB link to an HP-85 microcomputer, HP9121 dual 3.5-in flexible disc drive, HP7460 plotter and HP2225A “think-jet” printer. Data manipulation was per- formed on either an HP-85 or an HP-300 Chemstation com- puter coupled to a 10-MB Winchester disc and a colour monitor. The mobile phase contained various proportions of aceto- nitrile and sodium acetate buffer, depending on the degree of separation required. The flow-rate was 1.5 ml min-1 with sample injection volumes of 50 pl.The LDA detector was set to monitor six wavelengths at 204,220,240,250, 268 and 284 nm (Ak = +2 nm) with a reference wavelength of 550 k 20 nm. These wavelengths were selected after inspection and compari- son of the two spectra (Fig. 1). Results and Discussion General Methods Methods often generally recommended for assessing peak purity involve comparison with an external standard and include: (i) change in retention time, either with reference to the point of injection or with respect to an internal standard or when observed at different wavelength@; (ii) change in peak width at half-height; (iii) change in peak symmetry; (iv) change in the absorbance ratio between two wavelengths at the peak apex, compared with a standard; and (v) change in peak height or area.Results obtained using binary solutions of theophylline (TH, 52.57 pg ml-1) and paraxanthine (PX, 0-52.5 pg ml-1, equivalent to 650% mlm total content) are shown in Fig. 2. There was no significant change in the observed peak retention time during the experiment. However, the other methods did show a degree of variation depending on the amount of PX present. In general, the sensitivity of these methods appears to be 5-10% mlm PX in the mixture. The peak symmetry method was found to be exceptionally sensitive to the sample solvent composition and further experiments showed marked peak shape deterioration in proportion to the amount of methanol in the sample.In general, these methods require careful validation and the results should be compared with those obtained from a known pure standard. Their performance is directly related to the analyst’s knowledge of the system under investigation and the chromatographic separation of the analytes. Qualitative Methods Some methods have been developed specifically to permit qualitative investigation of the data set , often comparing various regions or the total surface of the spectrochromato- graphic data. These methods include (i) three-dimensional plots; (ii) contour plots; (iii) normalised spectral comparisons; 400 300 200 100 0 Second derivative 2 - - 1 - -2 - -3 - -4 - 4.4 4.5 4.6 4.7 4.8 4.9 5.0 1 0 - 1 Time/mi n Fig.4. p-xanthine (52.5 pg ml-1) and theophylline (52.51 pg ml-1) mixture, R, = 0.28. For chromatographic conditions, see text Comparison of zero-, first- and second-order derivatives of the elution profiles for (i) p-xanthine (58.1 pg ml-1) and (ii),ANALYTICAL PROCEEDINGS7 MAY 1988, VOL 25 153 and (iv) absorbance ratio throughout the complete peak between two specified wavelengths. Three-dimensional plots were among the original methods proposed for the presentation of spectrochromatographic data,2 especially if this could include viewing the data from various perspectives. 10 Another method that was developed to circumvent the problem of “hidden peaks” due to fixed-angle viewing was that of representing the spectrochromatographic data in two-dimensional cartographic contour form.11 For non-homogeneous peaks, the spectra collected during the peak will vary, depending on the proportion of impurity present. Comparison of, for example, the normalised apex spectrum with that obtained from the upslope or downslope spectrum or with that obtained from a library could give some qualitative measure of the degree of peak purity, provided that there are sufficient differences between the spectra con- cerned. 1 2 ~ 3 The well established absorbance ratio (AR) technique from analytical spectroscopy has been successfully transferred to the time domain. 10 Two distinct approaches have been developed for the implementation of this method. The first involves the collection of a spectrum from some point in the chromato- graphic peak and the calculation of a number of AR values between specified pairs of wavelengths.These ratios are then compared with those similarly obtained from a pure standard and the results used to assess identity and purity.14315 The second approach involves the monitoring of one AR through- out a chromatographic peak,8>10 which should yield a square- wave function for a pure solute. The result is often dependent on the pair of wavelengths chosen. Furthermore, incorrect conclusions may be drawn from the standard plots obtained from some instruments. These occur due to the plotting routines involved whereby AR = 1 are discriminated against and the normalisation algorithms used may give undue weight to noise in the result. Cheng and Gaddel6 have suggested alternatives to the algorithms in order to overcome these problems and to provide some statistical limits to the results obtained (Fig. 3).Quantitative Methods Many of the quantitative methods that have been developed work on a data set containing only a limited amount of chromatographic or spectral data, while others are capable of operating on the complete spectrochromatographic data set. Of these algorithms some permit the quantitation of multi- component peaks, while others, such as derivative chromato- graphyl7-19 and spectral suppression,lOJO are limited to binary peaks. The use of time-domain derivatives to remove background interference in single-channel chromatography was proposed about 20 years ag0.17 More recently Grant and Bhatta- charyyals have proposed algorithms relating to the most appropriate choice of monitoring wavelength and Fasanmade et al.19 have proposed the use of pseudo-four-dimensional derivative contour plots to investigate peak overlap. In general, the order of derivative required to investigate a peak is inversely proportional to the chromatographic resolution of the underlying peak components at the wavelength chosen (Fig. 4). However, noise and satellite interference become a major limiting factor at and above the fourth derivative. The use of spectral suppression was first proposed by Carter et aZ.20 This method involves some prior spectral knowledge about the main component that is to be suppressed. The validity of the conclusions drawn following suppression of the main components is also dependent on the degree of spectral difference between any possible co-eluting component and the main suppressed analyte.However, even slight differences in spectra can be exploited to give levels of detection of 0.1% or less impurity in the mixture.21 The performance of the algorithm is independent of the chromatographic resolution between the components (in contrast to time-domain derivatis- 600 500 400 300 200 100 0 10 0 -10 - 20 3 Q: -30 E - 40 - 50 -60 (a) R, = 0.28 268 2 2 nm (A) 240 k 2 nrn (B) 1 ( b ) A - 4.0348 B 70 (c) A - 3.238 B 1 Timeimi n Fig. 5. Spectral suppression results for a mixture of p-xanthine (52.5 pg ml-1) and theophylline (52.51 pg ml-I), R, = 0.28. (a) Elution profiles at 240 k 2 and 268 k 2 nm; ( b ) theophylline selectively suppressed to detect p-xanthine; and (c) p-xanthine selectively suppressed to detect theophylline ation), as it is dependent on spectral dissimilarities, the value of the suppression constant and the noise in the system for quantitative sensitivity (Fig.5). Other methods that have been developed for the quantita- tive investigation of multi-component chromatographic peaks approach the problem differently, using multi-dimensional mathematical methods applied to “overdetermined” systems. Partial least-squares can only be used where the analyst has information about all the components co-eluting under the peak. However, if this is not the case there are three possible approaches to the problem. (i) If the data set contains only multi-wavelength data, then the number of components can be determined and quantified using principal component analysis (PCA) .22 (ii) If some spectral knowledge exists about at least one of the co-eluents, then multiple spectral suppression (MSS) can be used.23 Although both of these algorithms have been validated for general application, their performance is dependent on the wavelengths chosen and the computing ability of the hardware. (iii) If spectrochromatographic data are available these can be interrogated by reference to either the time domain or the wavelength domain.22 Depending on the amount of prior spectral knowledge relating to the co-eluting components, a number of methods can be applied: curve resolution, factor analysis, multi-component analysis and target factor analysis.An approach from the time domain may involve iterative target factor analysis on the whole data set, or PCA or MSS on a subset of the spectrochromatographic data.The method chosen for quantitative analysis of an impure peak therefore depends on the amount of prior knowledge154 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 about the peak, the type of data set available and the degree of peak non-homogeneity . Conclusions and Future Developments There is a wide number of tests available for assessing chromatographic peak purity or non-homogeneity; the approach chosen will depend on the answer required-qualita- tive or quantitative. As peak impurity assessment is highly dependent on the degree of non-homogeneity throughout the peak, the probability of co-eluent detection is directly depen- dent on the information possessed, the time available for data manipulation and the knowledge of the chromatographic and mathematical systems involved, and inversely proportional to the resolution of the co-eluting components and their spectral similarity.Consequently, not every method will give the same result from a particular set of data, although some methods are more generally applicable than others. Each of the methods described has been validated and the robustness, selectivity, sensitivity and limitations evaluated by various groups of workers. As LDA detectors become more generally introduced and software is continually updated, the general utilisation of many of these methods will increase. As the pharmaceutical industry moves towards an increasing appreciation and use of chemometric methods for chromato- graphic validation, it will be interesting to observe the extent to which these approaches to the problem are documented in future publications of the British Pharmacopoeia.The authors thank Mr. R. S. I. Roberts (ICI, Plant Protection Division) for his help with the Cheng modification program. References 1. Van Rompay, J., J. Pharm. Biomed. Anal., 1986, 4, 725. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. Denton, M. S . , De Angelis, T. P., Yacynych, A. M., Heineman, W. R., and Gilbert, T. W., Anal. Chem., 1976,48, 20. Catterick, T., J. Chromatogr., 1983, 259, 59. Clatt, L. N., J . Chromatogr. Sci., 1979, 17, 225. Pardue, H. L., Top. Autom. Chem. Anal., 1979, 1, 163.Richie, J. M., in Goodman, L. S . , and Gilman, A., Editors, “The Pharmacological Basis of Therapeutics,” Fifth Edition, Macmillan, New York, 1974, pp. 367-378. Rankin, R., MSc Thesis, Heriot-Watt University, 1985. Willems, H. J. J., Van der Horst, A., De Goede, P. N. F. C., and Haakmeester, G. J., Pharm. Weekbl., Sci. Ed., 1985, 7, 150. Wright, A. G., Berridge, J. C., and Fell A. F., Chromato- graphia, 1987, 24, 533. Fell, A. F., Scott, H. P., Gill, R., and Moffat, A. C., J. Chromatogr., 1983, 273, 3. Fell, A. F., Clark, B. J., and Scott, H. P., J. Pharm. Biomed. Anal., 1983, 1, 557. Miller, J. C., George, S. A., and Willis, B. G., Science, 1982, 218, 241. Schieffer, G. W., J. Chromatogr., 1985, 319, 387. Law, K. H., and Das, N. P., J. Chromatogr., 1987, 388,225.White, P. C., and Catterick, T., J. Chromatogr., 1987, 402, 135. Cheng, H., and Gadde, R. R., J. Chromatogr. Sci., 1985,23, 227. Kambara, T., and Saitoh, K., J. Chromatogr., 1968,35, 318. Grant, A., and Bhattacharyya, P. K., J. Chromatogr., 1985, 347, 219. Fasanmade, A. A., Fell, A. F., and Scott, H. P., Anal. Chim. Acta, 1986, 187, 233. Carter, G. T., Schiesswohl, R. E., Burke, H., and Yang, R., J. Pharm. Sci., 1982, 71, 317. Marr, J. G. D., in preparation. Vandeginste, B., Essers, R., Bosman, T., Reijnen, J., and Kateman, G., Anal. Chem., 1985, 57, 971. Marr, J. G. D., Horvath, P., Clark, B. J., and Fell, A. F., Anal. Proc., 1986, 23, 254. Validation of Analytical Methods Michael Martin-Smith and David R. Rudd Pharmaceutical Analysis Division, Glaxo Group Research, Ware, Hertfordshire SG 12 ODJ Validation of an analytical method, which may be defined as its proper systematic evaluation so as to demonstrate that it is scientifically sound within the conditions limiting its applica- tion, is a necessary exercise to ensure that the method is capable of objective use in different laboratories giving reproducible and reliable results.Strictly, an analytical method can be proved to be valid only with respect to the particular apparatus employed in the validating exercise, but with modern equipment there should normally be few problems created through changes in make or model of instrument, On occasion, however, problems can arise, such as the deterioration of the chromatography, which can be seen within an HPLC assay procedure as a result of variability in a given type of stationary phase from manufac- turer to manufacturer and from batch to batch from the same manufacturer, changes in volume from one type of detector cell, with its connective tubing, to another, inadequacy of guard columns, or whether or not the autosampler has a functional mixing loop in those instances where the sample solutions for the injections have been made up in a solvent other than the mobile phase.Proper method validation is of particular importance in relation to the analyses of medicines where assurance of the continuing efficacy and safety of each batch manufactured relies solely on determinations of quality. Ability to control this quality is clearly dependent upon the ability of the analytical methods, as applied under well-defined conditions and at established levels of sensitivity, to give a reliable demonstra- tion of all deviations from target criteria such as content of active principle and preservatives, polymorphic form, permit- ted levels of impurities, etc., were any such deviations to occur.The requirements for method validation will, in general, depend both upon the particular test being conducted and upon the method being applied. With respect to a test for identity, where it can normally be assumed that sufficient sample is available for the test, thus ruling out considerations of sensitivity, choice of method largely determines the presence or absence of ambiguity. Methods such as X-ray crystal structure determination or solid state infrared spectroscopy can be expected to provide unambiguous identification, including definition of poly- morphic form, but spot colour tests or ultraviolet spectra, being primarily functional group or chromophore dependent , are prone to represent equivocal criteria.Full validation of chromatographic methods to be employed for the determinations of related substances requires confirma- tion that some ten features of the method are satisfactory: namely, stabilities in solution and within the chromatographic system; selectivities with respect to each related substance; response factors for each substance; limits of quantitation; limits of detection; accuracy; precision under conditions of repeatability; robustness; adequacy of method performance control; and precision under conditions of reproducibility.This is a consequence of the fact that it is not possible to determineANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 purity in a direct manner. It is only possible to demonstate the presence or absence of deliberately sought impurities at given levels of detection through application of methods appropriate to the impurity being sought. In order to demonstrate the absence of potential interfer- ences or contamination it is necessary to have available authentic samples of all likely (major) impurities of synthesis, and of those products of degradation which could be formed during the manufacture of the finished product or with time under all normal conditions of storage to which the raw materials or the finished product are apt to be exposed, so as to mount challenge experiments to confirm selectivity and sensi- tivity within the methods being applied.In chromatographic procedures there needs to be account- ability for compounds which travel with the solvent front or which do not migrate on the chromatographic system, accoun- tability for compounds which do not give a measurable or significant response with the detection system employed, and demonstration of full base-line separations of all peaks or of full resolutions of all spots in those instances where the compounds concerned do give a response with the detection system employed. Appropriately selected, accelerated degradation studies with isolation and full structural identification of the products formed are particularly informative as they will reveal degrada- tive pathways that could be operative during normal storage of the material, and they can be expected to provide authentic materials with which to conduct challenge experiments so as to confirm that were degradation to occur, it would be revealed by the analytical methods applied.Because normal storage is likely to involve exposure only to heat, light, the atmosphere (water vapour, molecular oxygen and carbon dioxide), co-ingredients in the product and components of the packaging, artificial degradation studies should normally involve only the accelerated application of these same influences. Where light, atmospheric influences or packaging are found to be deleterious, their effects can usually be eliminated by suitable changes to the packaging. Where aqueous solutions are involved, it is necessary to conduct appropriate accelerated studies in order to ascertain the pH dependence of any hydrolytic degradation.With ranitidine hydrochloride, a drug effective in the treatment of duodenal ulcers and related conditions, such experiments1 proved a crucial element in the formulation of stable solutions for injection. Accuracy in a method can be assessed through a combination of several investigations, for example, demonstration of the range of linearity, calculation of the correlation coefficient, determination on the bias, estimation of the total systematic error as by Youden plot and the application of appropriate recovery experiments. Precision under different conditions will be determined by 15s appropriate replicate experiments and the assessment of confidence limits, while evaluation of sensitivity should embrace determination of the limit of detection as a multiple of the background noise and the minimum quantifiable level, expressed as a defined limit to the relative standard deviation (RSD) over a defined number of repeat determinations.Robustness can be regarded as a lack of sensitivity of the method to changes in laboratory and environmental condi- tions, including pH, temperature, mobile phase composition, batch of stationary phase, etc. Once the influence of such variables has been ascertained it is then possible to ensure control of the performance of the method by suitable incorpor- ation of limits placed upon system suitability parameters, such as peak shape, retention time ranges, resolution factors, temperature of operation, RSD over a defined number of replicates, etc.A major consideration, which in the past would not seem to have received the consideration it merits, is that while the original validation of a method will prove its inherent capability, the real concern must lie with its actual performance at the time of its application to generate required data. With the availability of modern computing power, we now apply such confirmatory method validation concurrently with the generation of required assay data within our HPLC methods, by what may be considered the use of an “external” internal standard. We achieve this end by replacing the calibration solution of the analytical reference standard of the substance under assay, as traditionally applied in externally standardised HPLC methods, by three separate calibration solutions, appropriately interspersed with sample solutions to a predetermined, statistically valid protocol.These three standard solutions consist of: firstly, a solution of the standard at 100% of the nominal concentration of the analyte, spiked with the related substance or potential interfer- ent established as having the closest retention time on the system to that of the analyte; secondly, a solution of the standard at (100 + x ) % of the nominal concentration of the analyte; and thirdly, a solution of the standard at (100 - x)”/o of the nominal concentration of the analyte, where x has a value of 10 to 50, depending upon the results of the original “range of linearity” validation experiments.It is thus possible to monitor the values of the resolution factor, retention times, linearity, peak symmetry and column performance (plate count) throughout the whole chromato- graphic run. The RSD’s of the response factors of the calibration solutions throughout the run give a measure of the precision being achieved, while the constancy of all parameters measured reflects the robustness. Reference 1. Haywood, P. A . , Martin-Smith, M., Cholerton, T. J . , and Evans, M. B., J. Chem. SOC. Perkin Trans. I, 1987, 951. Stability Testing-the Practicalities A. J. West Fisons plc, Pharmaceutical Division, Research and Development Laboratories, Bakewell Road, Loughborough, Leicestershire LE7 7 ORH Stability testing of pharmaceuticals is internationally accepted as the procedure by which stability data are generated in support of finished product shelf life.It involves long-term storage testing of a number of batches of product, and tends to This paper attempts to explore the underlying reasons for carrying out expensive stability trials, and to suggest how the workload can be optimised without jeopardising the quality of the finished product throughout its shelf life. be extremely- analysis intensive. The magnitude of the ana- lytical workload is a direct function of protocol design, together Why Carry out Stability Testing? with the degree of over-all involvement of the analytical unit with the production - marketing areas responsible for bringing about the underlying reason for implementing stabil- ity trials. Any attempt to optimise (or minimise) the analytical workload associated with stability trials is destined for failure unless the stability unit is involved early enough, and deeply enough, with the decisions regarding the initial purpose for stability trials.156 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 There are instances (e.g., the development of a new chemical entity) where the need for stability testing is obvious, and others where it is rather less obvious.Optimisation, and continual review, of workload is only possible if the stability unit is involved with, and committed to, the particular project responsible for initiating the studies. There are four major reasons for carrying out stability studies.New Chemical Entities This is obvious and merits little further discussion. If a new chemical entity is developed into a finished dosage form, then that dosage form must be placed on long-term storage studies in order to determine shelf life. Product Line Extensions Again the need for stability testing is obvious. Examples of this type include the use of sustained release technology, e.g., solid dosage form reformulated to give twice daily dosing instead of four times daily dosing, together with additional formulations for specific patient groups, e.g., paediatric oral liquids devel- oped as an alternative to tablets. Marketing Variants Clearly, if marketing can bring about a change to a product which results in greater sales, then that change will be taken very seriously by any pharmaceutical company.Unfortunately, implementation of that change is almost always impossible without prior long-term storage testing. Examples in this class are: pack/product changed to improve “image,” e.g., colour change; product reformulated to remove particular excipients, e.g., removal of artificial ingredients for over the counter vitamin products; “device” included on product pack, e.g., metered dose pump included on nasal spray. Cost Saving Variants If the cost of manufacturing a pharmaceutical product can be reduced, without adverse effect on either product quality or sales, then again this is taken very seriously by any phar- maceutical company. Examples are: more cost effective synthetic route for active ingredient; more cost effective product manufacturing procedure; less expensive packaging materials; dual sourcing of packaging materials.Optimisation of the workload associated with long-term storage tests is only possible if the stability unit enjoy a strong working relationship with their counterparts in Marketing and Production. This allows the unit to review the usefulness of its project portfolio continually, and make cuts as appropriate in the light of the current marketing and production situation. Stability Protocol Design The protocol for a stability study describes the agreed programme of work necessary to achieve all foreseen objec- tives. The protocol contains information concerning the number of batches to be studied, the storage conditions, storage periods and analytical methodologies.Clearly, the stability protocol directly controls the magnitude of the analytical workload. It is vital that there is optimisation between the amount of work necessary to achieve ethical or regulatory aspects and the undertaking of excessive analytical testing. Each stability testing protocol should be uniquely designed to fit the requirement of the particular project. However, it is felt that there are two different fundamental types of approach to protocol design. The “Arrhenius” Approach In essence this involves storage at 3 to 4 accelerated storage conditions up to 45 “C, and calculation of the rate constant at each temperature. This information can then be used to predict the rate constant at room temperature, using a standard Arrhenius approach. This suffers from many disadvantages.Firstly, it is very analysis intensive owing to the large number of storage conditions; secondly, it is useful for only chemical degradations (very rarely the case); thirdly, it is not applicable to heterogeneous formulations, e.g. , tablets, ointments, etc. ; fourthly, it often does not work in practice!; fifthly, it is not favoured by outside registration authorities. The Linear Regression Approach This involves only minimal accelerated testing and principal storage at one temperature, e.g., 25 “C. The particular degra- dative effect governing product shelf life is plotted by linear regression at this temperature, with shelf life determined either using real time data or extrapolation from real time. It is customary to include 95% one-sided confidence limits on the regression line.This approach offers advantages over the former, i.e., it is much less labour intensive as a result of the lower number of storage conditions, it can be applied to any type of degradation, e.g., absorption, moisture loss, chemical losses, etc. (obviously, logarithmic linearisation may be appropriate in certain instances) and the approach is favoured by outside registration authorities. Wherever a linear regression approach is used for a stability protocol, the shelf-life is directly related to the 95% confidence limits imposed on the linear regression degradation line. The confidence limits themselves are related to analytical quality, as shown in Fig. 1. Hence, shelf life maximisation is possible only if the quality of analytical data generated is maximised.Ways of achieving this are as follows. Y - r 100, I az751 ’ ’ ’ * ‘ I I ’ I ‘ ‘ I ’ ’ ’ 2 0 6 12 18 24 30 360 6 12 18 24 30 36 D Room temperature storage time/months Fig. 1. Linear regression plot with 12 months’ storage data. (a) “Narrow” confidence limits; ( b ) “wide’’ confidence limits Replicate Analyses Clearly, if an analytical procedure is accurate, then precise results can be obtained by replication, e.g., each analysis carried out in duplicate by three operators. However, this is not practical as it is too labour intensive. Automate Analyses This often results in an inherent improvement in precision, and can also serve to increase replication with only a minimal increase in labour intensiveness.It is therefore considered to be vital to the successful generation of stability data. Examples are: the inclusion of autosamplers on chromatography systems; the use of flow cells on spectrophotometers; the use of automatic dilution equipment; the use of computer driven equipment and balances; and data management by LIMS. General Quality Improvement This is relatively obvious, although nonetheless extremely important. Key aspects of this are that one should continually strive to improve methodology, to ensure that staff are trained and motivated, to ensure that equipment is of good quality and adequately maintained and to ensure that environmental storage facilities are of good quality. Conclusion Stability testing of pharmaceutical finished dosage forms needs to be carried out with an optimised workload.A workload canANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 157 only be optimised if the stability unit is fully involved with its “customer,” i.e., Development, Marketing and Production. One advantageous approach to protocol design is to focus on the linear regression analysis of “room-temperature” data. This approach is at its most successful if analytical quality is maximised throughout the stability study. The Evolution of Methods for the Determination of Heavy Metals R. N. P. Farrow and G. F. Lewis Analytical Department, BDH Limited, Broom Road, Poole, Dorset BH 12 4NN The pharmacopoeias have described variations of a visual colorimetric test for heavy metals. A test solution of the sample was prepared, together with comparison standards containing known amounts of lead.The pH was adjusted to between 3 and 4. This was followed by an addition of hydrogen sulphide water or, in later versions, of thioacetamide reagent (which hydrolysed to give sulphide ion). The lead sulphide colour of the sample was matched against those of the standards. The “heavy metals” included lead, copper, mercury, bis- muth and cadmium. The method could be made selective by adding cyanide to complex copper and cadmium. This simple procedure gave a reasonably reliable measure of heavy metals as so defined. In the 1960s, two factors greatly improved colorimetric analysis. One was the development of organic complexing agents for metals. A complexing agent usually possessed one or more acidic hydrogens and one or more unbonded electron pairs. The metal atom was thus held at the centre of a compact and stable molecule. The complex could often be extracted into a non-aqueous solvent.The solution was often coloured and the intensity could be measured. By adjusting the pH it was possible to exploit differences in stabilities between complexes by altering the pH. In this way, one metal could be determined in the presence of another. Selectivity could also be achieved by the use of masking agents. The other factor was the development of the spectropho- tometer. By this means accurate absorbance measurements could be made, the optimum wavelength could be chosen, thus increasing sensitivity and permitting the measurement of one complex in the presence of another, and calibration curves could be readily constructed. The appearance of recording instruments enabled us to study the complete spectrum and so optimise the experimental conditions.The early nineteen-sixties witnessed an “Indian Summer” for chemistry applied to analysis, with the publication of many hundreds of methods based on this principle. Running parallel were the polarographic methods. In the simple version, an increasing negative potential was applied to a dropping mercury cathode and the diffusion current was plotted against potential. Later, the cathode-ray polarograph was developed, in which a synchronised potential sweep was applied during the last two seconds in the life of each mercury drop. The potential was applied to the “X” plates of a “long-afterglow” cathode-ray tube.The cell current, which increased during each sweep, was passed through a load resistor, the potential drop was amplified and the signal fed to the “I”’ plates. Thus, every 7 seconds, a polarogram was traced across the screen. When viewed in subdued light the trace remained visible as a continuous picture. Anodic stripping polarography was a further development. The test solution was electrolysed for a given period using a stationary mercury cathode. The current was then reversed, making the electrode the anode and the concentrated metal that had been deposited in the mercury drop was “stripped” back into solution. The cell current was thus magnified many times, giving much higher sensitivity. Then, in the 1960s, atomic absorption spectroscopy made its appearance, and revolutionised the determination of trace metals.Its outstanding characteristic was the narrowness of atomic absorption band widths, resulting in very little spectral interference. Standard addition calibration was generally used, employing more than one standard to guard against non-linear response. Sensitivity can be improved by extracting the metals as their ammonium pyrrolidone dithiocarbamate complexes into a non-aqueous solvent. A limiting factor is the inefficiency of the nebuliser system through which only a small fraction of the sample reaches the flame. Improved models have been developed in which this problem has been partially overcome, but sometimes they give rise to other problems, such as blockage of the burner slot. Further developments include electrothermal vaporisation, hydride generation (of certain elements) and the cold vaporisation of mercury. The current method for analysing samples for a wide range of elements is inductively coupled plasma spectroscopy (abbre- viated to ICP). Atomic emission is produced by introducing the test solution via a nebuliser into a stream of argon, where it is vaporised. Ionisation is produced by an electrical discharge and an induction coil produces a plasma with a temperature exceeding 10 000 “C. The method gives high sensitivity, low background emission and a wide range of linear calibration. Two instruments are used at BDH. A Radyne-Hilger instrument gives a simultaneous readout for all of the selected elements. An ARL 3520 fully computerised instrument reads the elements sequentially and gives greater flexibility. The determination of heavy metals is straightforward for many samples but salts produce several difficulties. Firstly, the emission intensity can be altered, causing a change in the calibration slope. Secondly, the background shift is generally increased. Thirdly, the uptake rate may be changed as a result of an alteration in viscosity. Fourthly, the salt may cause blockages in the injector tube or nebuliser. For these reasons, matrix-matched standards are used. Sometimes, direct analysis does not provide sufficient sensitivity. Solvent extraction can be used but it has its limitations. Separate determinations are needed for extracted and non-extracted metals, special plasma conditions are required and it is often difficult to remove solvent contamina- tion from the nebuliser system. These problems can be overcome by a back-extraction procedure. Suppose we start our analysis by preparing 100 ml of a 5% mlV aqueous solution. We divide this into 90-ml and 10-ml aliquots and we set the latter on one side. We next form the dithiocarbamate complexes of copper, lead, iron, zinc and nickel present in the 90-ml aliquot and extract them into Freon, thus separating them from calcium, magnesium, sodium, potassium, aluminium and barium. We then add the extract to the 10-ml aliquot and acidify the solution with nitric acid. The complexes are decomposed and pass back into aqueous solution as metal ions. In this way we achieve a ten-fold concentration of the complexable metals without incurring the disadvantages of direct solvent extraction. The latest development is to use a mass spectrometer to measure the ion concentrations in the inductively coupled plasma. An ICP-MS instrument has extremely low detection limits, taking us into the pg ml-* range and beyond.

ISSN:0144-557X    

DOI:10.1039/AP9882500147

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

158 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 The Futurc-Peptides and Proteins as Drugs S. S. Davis Department of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD Background Recent advances in recombinant DNA technology and chem- ical synthesis through multi-step procedures have now made available to us a wide range of biological response modifiers in the form of polypeptides. These include human growth hormone, tissue plasminogen activator, tumor necrosis factor, interleukins, interferons, insulin, calcitonin, somatostatin, LHRH, etc. Some of these materials have already been registered with regulatory authorities and a few have reached the market place. One substance of course, insulin, has been a familiar therapeutic agent for many years.In general, these various biological regulators are effective in very low doses and normally differ in their mode(s) of action to conventional low relative molecular mass drug molecules. They can act in multi-component (cascade) systems, where more than one mediator may be required for action. This can include the phenomenon of “up-regulation,” where a precursor cell may need to be primed by one mediator before a second mediator can produce an effect. The timing of such “up-regulation” can be critical. Attempts have been made to define the relation between peptide structure and action. For example, recently Kaiser has suggested that such molecules can be split into three basic structural units. For the molecule beta endorphin, he suggested that the molecule comprised a specific recognition site, a hydrophilic connecting link and an alpha helix.Similar analyses on other molecules may lead to a better understanding of the critical regions giving rise to biological effect and thereby the synthesis of simpler species. It is known that the activity of large polypeptides is dependent not only on primary and secondary structure, but more particularly on tertiary structure (i.e., a required conformation) as well as quaternary structure in the form of oligomeric associations. Starting with natural molecules, analogues can be developed that have increased selectivity and stability. Similarly, by modifying side-chain structure or conformation, antagonist analogues can be pro- duced. Pharmacokinetics Within the Pharmacy Department at Nottingham, we have a special interest in the design and evaluation of delivery systems for peptide drugs.In developing an appropriate delivery system, the following factors need to be considered: kinetics, stability, assay, route, immunogenicity. As with any other delivery system, the basic questions that need to be answered are: where does the drug need to go to?; how much needs to be there?; and how often? Unfortunately, with peptides and proteins, the answers to these simple questions are not always forthcoming. For example, the required concentration versus time profile is often ill defined. Unlike conventional drugs, where steady-state concentrations at a receptor may be adequate, peptides may need to be pulsed to mirror the endogenous situation.Certainly, one would expect differences between agonist and antagonist action. Furthermore, the well known phenomenon of “down-regulation” and tolerance that can occur may even be exploited for certain molecules, for example, LHRH in the treatment of prostatic carcinoma. In some instances, very well defined dosing patterns are required. For example, for gonadotrophin releasing hormone, the required schedule to induce ovulation is 15-20 pg for 1 min, every 90 min for 9-16 d. The only available means of delivery in this instance is to use an external pump system. In contrast, in the treatment of prostatic cancer using LHRH analogues ( e . g . , nafarelin) with implanted microsphere systems, the release patterns can fluctuate quite widely provided a minimum level of drug is released as this results in down-regulation and reduced testosterone levels.Stability Polypeptide and protein drugs are unstable in vitro and in vivo because of their chemical nature. Inactivation can occur by chemical changes, such as fragmentation, enzymatic clipping, deamination, covalent dimerisation, etc. Physical changes include unfolding, non-covalent aggregation and adsorption. Chemical methods can be used to produce more stable analogues, particularly by modifying the peptide backbone. Similarly, peptide aggregation can be controlled by altering peptide structure, once the mechanism of self-association is understood (usually through the involvement of intermolecular hydrogen bonds and hydrophobic interactions). Analysis The analysis of protein drugs presents considerable difficulties because the materials are normally available at low concentra- tions and there is not always a clear relationship between purity and activity, Polypeptide systems can be heterogeneous, in that more than one species may have biological activity.In defining chemical composition, it is important to bear in mind aspects relating to chirality, conformation and aggregation. The presently available methods for the analysis of peptides and proteins include bioassay, immunoassay , enzyme assay and physical and chemical approaches. Bioassays tend to be variable and of poor reproducibility, and consequently im- munoassays are to be preferred. These last can handle low concentrations but it is important to realise that the portion of the molecule recognised in the assay procedure may not necessarily be associated with activity.New developments in enzyme assays, where the drug acts as an enzyme or inhibitor or stimulator of enzyme action, can lead to very large amplification factors and are able to detect very small doses indeed. The physicochemical assays that are appropriate include standard methods, such as total protein content and separation of molecular species, but also include amino acid composition, amino acid sequences and conformational analy- ses on enzyme (tryptic) digests. Advanced techniques such as FAB mass spectrometry are also applicable. Immunogenicit y The administration of a polypeptide drug can give rise to an immune response, either because of the presence of small amounts of misfolded or partially degraded material or to high concentrations of the active molecule itself.Such reactions can be avoided by exploiting the so-called tolerogen concept, where the immunogenic determinants are masked or are attached to known tolerogenic materials such as polyethylene glycols and dextrans. In this way, it is possible to increase the stability and biological half-life of polypeptides as well as to minimise greatly immune reactions. Delivery Systems A wide variety of delivery systems has been proposed for peptide drugs. Those that have successfully reached the clinic include implant systems and nasal sprays. Although it would beANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 159 beneficial to be able to administer peptides via the oral route, this is fraught with difficulties.It is to be expected that high molecular weight polypeptide will be degraded by enzymes either present in the gastrointestinal lumen or present within the cells lining the gastrointestinal tract. Normally, only very small amounts of material are able to be absorbed but some materials, such as cyclosporin, are taken up to a moderate extent (25-50%). A further understanding of the absorption of species within the gastrointestinal tract is essential before appropriate delivery systems can be developed. For example, the different roles of paracellular and transcellular absorption need to be established and then mechanisms sought to exploit such processes. Nasal administration of peptides and proteins is becoming increasingly popular.A wide variety of materials has been administered in this way and a number of products marketed. Some molecules are well taken up in their own right, whereas others can be absorbed through the exploitation of so-called absorption enhancers or the concept of gelling microspheres. For all such systems, it will be important to take credence of the toxicological consequences, especially in relation to chronic dosing. In summary, polypeptide and protein drugs are now a reality. These high molecular weight polar species are very different from conventional low molecular weight drug mole- cules. Consequently, the pharmaceutical scientist is faced with analytical problems in all stages of the development of these materials and advanced analytical techniques have an im- portant role to play.Further Reading Davis, S. S., Illum, L., and Tomlinson, E., “Delivery Systems for Peptide Drugs,” Plenum, New York, 1987. Regulatory and Technical Problems in the Control of Monoclonal Anti bodies 6. C. Lewis Celltech Limited, 228 Bath Road, Slough, Berkshire SL 1 4EN The purpose of this paper is to give a brief overview of some of the problems, both regulatory and technical, that one encoun- ters in the production and quality control of monoclonal antibodies and other products of the biotechnology industry. Many of these problems appear to be unique to the biotechnol- ogy area, and in no small way are due to the nature and origin of the cell lines and biological raw materials used in the production process. Basically, because our raw material is usually some type of transformed cell line of animal or human origin, e.g., a hybridoma or a recombinant cell line possessing the gene coding for the desired polypeptide to be expressed, the many guidelines or regulations pertinent to our industry are very much concerned with ensuring that any therapeutic substances made with such materials are safe for the patient.For therapeutic products a master and working cell bank must be laid down under carefully defined conditions. The cell bank must be tested to ensure that it is sterile, and mycoplasma free, and that it is free from contamination by named viruses - retroviruses, depending on the origin of the cell line. Myco- plasma are the smallest free-living micro-organisms and can play havoc with tissue culture processes.No cell line is handled in production until it has been shown to be mycoplasma free by means of the Hoechst-stain - tissue culture technique on Vero cells. Virus testing is both a costly and lengthy business and can cost up to f30 000 for full safety testing on a particular cell line - product combination. Virus testing is also required on other raw materials of animal or human origin used in the prepara- tion of tissue culture medium. In-process Assays Hybridoma cells taken out of liquid nitrogen storage are grown in tissue culture using a modified Eagles medium containing supplementary Foetal Calf Serum. The cell concentration is kept between 1-15 x lo5 viable cells cm-3 and the cell viability determined on a regular basis by using a differential stain uptake procedure.The volume of cell suspension is increased daily by addition of fresh medium until the cells are transferred from tissue culture flasks to roller bottles and then into an air-lift fermenter. Samples are taken daily and checked for viability, microbiological contamination and antibody content. The major problem in the above measurements is getting an accurate, rapid, assay result for the antibody concentration in order to harvest the fermenter when the antibody concentra- tion is at its maximum value. The conventional ELISA (enzyme linked immunosorbent assay) assay method, though very sensitive, is very time consuming and it can take up to 24 h to obtain a result. It is thus not ideal for an in-process assay. HPLC may be an answer to this problem, but the latter technique is itself not without its pitfalls when used to analyse IgG and IgM containing samples in the presence of large amounts of Foetal Calf Serum used as a medium component.Current procedure used at Celltech is based on a gel-permeation column but suffers from a lack of sensitivity compared with ELISA and also from interference from similar-sized proteins (e.g., Bovine IgG from serum co-elutes with Mouse IgG). We are looking at alternative systems and procedures in order to overcome these disadvan- tages. Another area that we are currently investigating is a routine HPLC assay for amino acid components of tissue culture medium, so that these can be monitored regularly and concentrations of actual components adjusted by further sterile additions to the fermenter as required.Finished Product Testing This is potentially the most difficult area of all, because all of the product has to be quantified and the customer charged accordingly. As with all biologicals, by definition there is no one simple method of chemical analysis that can be used to alleviate this situation. It is thus very important, when negotiating the contract with the customer, that steps are taken to remove any ambiguity when setting the product specifica- tion. Some of the techniques used at Celltech in the characterisa- tion - quantification of purified product are as follows. Absorbance measurement at 280 nm Purified proteins can be quantified by measuring their absorb- ance at 280 nm, the absorbance being principally due to the aromatic amino acid content.Because this varies from protein160 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 to protein, use of a “standard” absorbance value for a particular class of proteins can lead to errors. SDS-PAGE In this technique, the effect of different protein charges is minimised by their uniform association with sodium dodecyl sulphate and thus separation is due principally to differences in protein size. After staining of the gels with Coomassie Blue, the gels are scanned using a densitometer and quantified in order to assess protein purity. Some gel scanners are limited by the way in which the base line is calculated and spurious results can occur. The accuracy of single assays is of the order of +3%. HPLC (gel permeation) The old adage that you can make a single peak out of almost anything is the appropriate caveat for this method.Results should be treated with caution unless the method is fully validated. Methods are currently available for IgGs but no suitable columns for IgMs are yet available. Isoelectric focusing This technique is based on charge relationships. It is used to monitor batch to batch variation of a product. Like SDS- PAGE, it can be used with immunological methods to identify the bands seen. A major concern of regulatory bodies is any variation in glycosylation of proteins during processing or storage. Since many glycosyl groups are charged because of the presence of, for example, sialic acid residues, IEF is an important technique in monitoring product consistency. Potency (biological assay) This test is complicated by the relatively poor precision and accuracy of biological assays compared with conventional chemical assays.It is further complicated by a lack of suitable reference standards, validated or commonly agreed methods as well as suffering from inter-laboratory variations. Host cell DNA Current regulations limit contamination of finished product by host cell DNA to 10 pg per dose. The usual assay procedure is based on a hybridisation process using a radioactive synthetic oligonucleotide DNA probe, generally of 20-50 bases in length. The method has adequate sensitivity but is slow and labour intensive. Protein A residues Protein A, derived from the cell wall of Staphylococcus aureus, is used in downstream processing to purify crude tissue culture concentrates containing IgG antibodies as it has a selective binding action towards these materials. It is thus important to test for the presence of Protein A residues in the product as these may have antigenic effects in humans.A number of sensitive immunoassays have been developed and are used both at in-process and finished product stage. Endotoxin content (LA L ) The chromogenic LAL test for endotoxin content can give equivocal results on certain products as the product itself can interfere either positively or negatively with the test. For US regulatory purposes a US licensed test system should be used that has been validated against the product of interest. It is therefore much easier to use the LAL test for monitoring the cleanliness of the production process and carry out final product testing using the BP Rabbit Pyrogen procedure.Oligomers The theoretical concern with these compounds is antigenicity of unwanted aggregates. Many methods are possible including HPLC (gel permeation) , light-scattering, ultra-centrifugation and PAGE, etc. The multiplicity of methods is necessary for process validation and may also be needed as part of a batch specification depending on known chemistry and process validation results. Conclusion Assurance of product quality is derived from careful attention to a number of factors, including selection of appropriate grades of raw materials, adequate product/process design, in-process testing and end-product testing. Owing to the complexity of biotechnology products, routine end-product testing alone is not sufficient to assure product quality.Quality, safety and effectiveness must be designed into the product and process validation is a key element in achieving these aims. Applications of Robotics in the Pharmaceutical Laboratory A. N. Hale Sanofi UK Ltd., Floats Road, Wythenshawe, Manchester A423 9NF Since the 1950s and 60s, when analysis times were measured in days, there has been a general trend towards using increasingly sophisticated instruments which often allow analyses to be completed in minutes. By using modern computing power instrumentation has greater flexibility with better sensitivity and more accurate detection methods. The analyst’s role has changed from that of an operator to a supervisor, the instrument playing an ever increasing role in the control of its own operation. However, despite all of these advances, one area has remained generally resistant to automation and that is sample preparation.Commercial sample preparation systems have been available for some time but are often unsuitable for use in pharmaceutical laboratories, because of the wide variety of sample types which typically undergo routine analysis. For example, samples might include powders, tablets (including sustained release formulations), capsules, aqueous and non- aqueous liquids, creams, ointments, suppositories, aerosols and liposomes. The introduction, in 1982, of small-scale laboratory robots saw the beginnings of flexible automated sample preparation. Although robot arms had been available for some time, the introduction of a commercially available complete system was significant.A modular system, consisting of a robot arm and a controller (plus a high level language), using custom-made or existing analytical instrumentation, can be purchased. Each of the modules can operate independently, being controlled, as with the arm, at a computer terminal. Each system action or set of actions, for example, operating a vortex mixer or picking up a test-tube, can be given a command name written in English. These names can be put together in sequence to produce a programmed set of actions and in this way an automated preparation and analysis is created by the user. To be cost effective, a robot system generally needs to be in operation more or less continuously. This is relatively simple when large numbers of the same sample are involved.ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 161 However, often sample numbers are relatively small and, as already discussed, a variety of product types can undergo routine analysis.A multi-tasking system which can be rapidly changed from one application to another is therefore required. When examined as discrete operational units, analyses which may have previously been regarded as different are often very similar. The individual steps needed to analyse liquid and tablet samples are often duplicated, as in the following example. Liquid sample analysis Tablet sample analysis Operator sets up system Aliquot taken Tablet weighed Reagent added Diluent added Centrifuge Vortex Sonic and Vortex Inject on to HPLC/Fill autosampler vials Thus, the same robot system can be successfully used for the analysis of tablets, body fluids and pharmaceutical liquid samples.operate independently of the LIMS, the programs being held within the memory of the robot controller, see Fig. 2(a). This allows the operator to check the status of the robotic system and examine interim results without affecting the ongoing automated analysis. ( a ) w injector Autosampler turntable I Rack 1 [Rack] i dispenser Solvent I mixer Examples of Applications Using a Commercial Robotic System Assays developed to date by using a multi-tasking approach are as follows. Dissolution I bath 1 Bioanalysis Determination of cephalosporins in human serum and in extracted bone samples.Robot [ - Arm 1 r---- ---1 I [Autosamplersl .. Injectable liquid formulation Determination of two actives and a preservative. Determination of one active and its related substances. Tablet assays Determination of single entity and combination formulations; assays also quantitate the main degradation products. A future area for development is tablet dissolution testing. This is an important and rapidly expanding analysis in the phar- maceutical industry, but is repetitive and very time consuming. Much emphasis has been placed on its automation, but until the introduction of laboratory robots, total automation was difficult. The possibility of using the same robot system for tablet dissolution testing in addition to the methodologies described above has been examined.The specialised equipment needed to run dissolution testing on the same robot table as the existing liquid and tablet applications caused problems in creating enough space around the robot arm. Fig. l ( a ) shows the liquid and tablet multi- tasking table, which was already fairly cramped. Space for the dissolution equipment and associated modules can be created, for example, by replacing some of the racks with a vertical test-tube dispenser and by taking advantage of the 3-dimen- sional nature of the robot arm. In other words, some modules can be stacked at two levels: for example, solvents can be dispensed above the vortex mixer and the various hands can be held at two levels. Fig. l ( b ) shows the modified table; modules which the robot arm does not need to access directly, the spectrophotometer for example, are positioned under the system table.Fig. 1. ( a ) , Liquid and tablet multi-tasking robot table; (b), multi-tasking table with dissolution testing In order to achieve full automation it will be necessary for the programs to be in the LIMS, which then sends instructions to the robot one at a time, thereby controlling the analysis directly. The LIMS would be able to monitor progress and modify the next instruction to be sent based on the results of previous actions, Fig. 2(b). Options Sample r l t Sample Robot I HPLC UV GLC HPLC UV GLC v Future Developments Combining robot systems with Laboratory Information Management Systems (LIMS) has the potential to revolution- ise laboratory automation. In its simplest form the robot will LIMS LIMS 4 Fig.2. ( a ) , Simple robot - LIMS; ( b ) , integrated robot - LIMS162 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 For example, the LIMS - robot combination could begin an HPLC analysis, the results being continuously monitored by LIMS. An out-of-specification result could initiate the follow- ing check sequence: 1. Solution re-injected on to HPLC. 2. Solution prepared again and re-analysed. 3. Control solution prepared and analysed. If the control failed, the process would be stopped and an analyst alerted to a probable system problem. Alternatively, the system would conclude that the original result was analytically correct and continue with the remaining analyses. By using a multi-tasking robot table layout, a non-analyst could be instructed by the LIMS to supply the robot with solvents, reagents and the required samples.The LIMS would automatically select the correct sample preparation based on its own knowledge of the sample type and control the robot directly, automatically checking unexpected results. The LIMS could alert an experienced operator, that is an analyst, if a technical problem arose. In other words the non-analyst need make no analytical judgements. This could free the highly trained laboratory staff currently needed to run routine samples for more rewarding tasks, or it could allow Quality Control and Quality Assurance to be extended further into the production areas, allowing plant operators to monitor their process control directly. This could not only potentially reduce costs but, perhaps more im- portantly, improve the quality of pharmaceuticals.An HPLC Method for the Determination of 5-Hydroxymethyl Fu rfu ralde h yde in Inject ions Containing Dextrose J. S. Howells, D. Johnston* and P. R. Vojvodic Sterling Research Group-Europe, Alnwick, Northumberland NE66 2JH Dextrose can be used in pharmaceutical injection preparations either alone or in the presence of a drug substance to adjust the osmolarity of the solution. In both instances degradation of dextrose may occur as a result of autoclaving during manufac- ture or subsequent storage at elevated temperature. A complex degradation pathway has been elucidated1 and the major degradation product has been identified as 5-hydroxymethyl furfuraldehyde (5-HMF).HOCHP HO $qH - HoH2cocHo 5-HMF H OH Dextrose Both the USP2 and BP monographs3 for Dextrose for Injection include a simple ultraviolet (UV) spectrophotometric limit test for “5-hydroxymethyl furfuraldehyde and related substances.” At the chosen wavelength of 284 nm dextrose has no absorbance and the absorbance of 5-HMF is at a maximum, but the method is not selective and other compounds may contribute to the measured absorbance. To comply with the monograph the absorbance of a 0.4% mlV solution of dextrose monohydrate (anhydrous in the BP) must not exceed an absorbance of 0.25. Assuming an A; value of 1316,4 this limit corresponds to a 5-HMF concentration of 1.9 pg ml-1 or 0.0475% mlm with respect to dextrose. If the formulation includes other compounds which absorb at 284 nm the pharmacopoeia1 ultraviolet method is inadequate and a more selective method is required.HPLC gives the Time- Fig. 1. Typical chromatograms for two injection formulations containing different drugs. Column, Spherisorb ODS ( 5 pm), 10 X 0.46 cm i.d.; mobile phase, methanol - water (1 + 9 VIV); flow-rate, 2.0 ml min-1; detector wavelength, 285 nm; detector sensitivity, 0.02 a.u.f.s.; and temperature, ambient. (a) Reference, 0.25 pg ml-1; ( b ) sample spiked with 0.025% 5-HMF with respect to dextrose; and (c) sample * Author to whom correspondence should be addressed. required selectivity and has already been applied to solutions containing only dextrose.5 Suitable HPLC conditions for 5-HMF have been developed and satisfactorily applied to two injection formulations con- taining different drugs, each of which has a significant ultraviolet absorbance at 284 nm.Typical chromatograms are shown in Fig. 1. The suitability of the method is demonstrated by the recovery of 5-HMF from spiked solutions and by comparison of data generated by using the new HPLC method with data from the UV method. The recovery of 5-HMF from spiked solutions is shown in Fig. 2. Recoveries were satisfactory at levels up to twice the product monograph limit set at 0.05% mlm 5-HMF with respect to dextrose and the limit of detection was determined as approximately 0.01 pg ml-1 of 5-HMF (0.002% mlm 5-HMF with respect to dextrose). 5-HMF added w.r.t. dextrose, YO Fig. 2. Recovery of 5-HMF from spiked solutions A comparison of data for samples analysed by HPLC and UV is shown in Fig.3. The values generated by HPLC compare favourably with those generated by UV. The instances where the HPLC method gives a lower value than the UV method may reflect, in part, the levels of “related substances” measured by the UV method but not included in the HPLC results. Differences between data generated by the two methods have also been noted by Taylor5 when studying pure dextrose solutions, and attributed to the failure of the HPLC method to include the related substances measured by UV.163 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 Conclusions / I 0.04 1 I Y a I ; 0.03 - v) 2 Y x -0 + 0.02 3 - L The pharmacopoeia1 method for the determination of 5-HMF in injection formulations containing dextrose suffers from lack of specificity when other UV absorbing compounds are present.In these instances, the HPLC method presented here has been demonstrated to be a viable approach, producing data comparable with those generated using the UV method. References 1. Taylor, R. B . , and Sood, V. C., J. Pharm. Pharmac., 1978,30, 510. 2. “USP XXI,” United States Pharmacopeial Convention, Rock- ville, MD, USA, p. 300. 3. “The British Pharmacopoeia 1980,” HM Stationery Office, 4. Taylor, R. B., Jappy, B. M., and Neil, J. M., J. Pharm. Pharmac., 1971, 23, 121. 5. Hung, C. T., Selkirk, A. B., and Taylor, R. B., Clin. Hosp. Pharm., 1982, 7, 17. 0 0.01 0.02 0.03 0.04 London, 1980, p. 600. 5-HMF w.r.t. dextrose (UV), % Fig. 3. formulation Comparison of UV and HPLC methods for 5-HMF in a typical An HPLC Method Employing Diode-array Detection for the Identification of Natural Plant Extracts Tolu Syrup and Wild Cherry Syrup in a Herbal Cough Remedy Benzoic J.S. Howells and D. Johnston* Sterling Research Group-Europe, Alnwick, Northumberland NE66 2JH I 1 Analytical tests to identify the two plant extracts tolu syrup and wild cherry syrup in a herbal cough remedy were required in support of a product licence application. The two syrups are manufactured from their respective tree-bark extracts, the source and known constituents of which are summarised below. Tolu Syrup BP Tolu balsam is obtained from a secretion from the trunk of the tree Myroxylan balsamum. It contains about 20% of free balsamic acids, benzoic and cinnamic acid (8% and 12%, respectively) .4 Other constituents include vanillin, benzyl benzoate (-SO/O), cinnamyl cinnamate and the esters of the balsamic acids with the resin alcohol, toluresinotannol.Tolu syrup, a sucrose based syrup prepared from tolu balsam, has mild antiseptic properties and is a common ingredient of cough mixtures. 1~ I I I I I I 0 1 2 3 4 5 6 7 8 9 Timeim i n Fig. 1. cherry syrup Chromatogram of tolu syrup recorded at 254 nm. WCS = wild Wild Cherry Syrup BP The sucrose based syrup is produced from the dried bark of the * Author to whom correspondence should be addressed. wild or black cherry tree, Prunus serotina. It contains (+)-mandelonitrile glucoside, which interacts with an enzyme system in the presence of water to produce benzaldehyde, hydrocyanic acid and glucose. Other constituents include various fatty acids, tannins, volatile oils and resinous sub- stances.The bark possesses little therapeutic value, its primary use is a flavouring agent, which imparts an astringent, bitter taste to the cough mixture.l-3 Other constituents of the herbal cough remedy are also of natural origin and include camphorated opium tincture, sucrose and apple concentrate. This results in a product which is a dark coloured, viscous, syrup mixture containing many resinous organic materials. A complex sample matrix of this type is difficult to analyse by conventional techniques, e.g., TLC and colorimetric analysis. A simple analytical technique was required with minimal sample work-up avoiding the use of solvent extraction procedures. 90 m 0 X 0, C lu F 2 v) 2 0 210 260 31 0 360 Wavelengthinm Fig.2. Peak spectral identity for tolu syrup HPLC Method Development An HPLC assay method was the favoured technique as the samples could be diluted with water and injected directly on to the column without further preparation. The majority of the unknown natural components of the cough remedy eluted164 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 rapidly on reversed phase HPLC columns. By selecting a column with high retention properties (i.e., CI8), the free balsamic acids were retained and resolved from the mass of unknown early eluting species. The acidic mobile phase used supresses the ionisation of the carboxylic acids, therefore increasing retention and producing capacity factors of four and eight for the benzoic and cinnamic acids, respectively.Tolu Syrup (Fig. 1) The chromatogram of the single ingredient tolu syrup pro- duced four fully resolved peaks, the balsamic acids and the preservatives methyl and ethyl para-hydroxybenzoates (parabens) . These preservatives, including benzoic acids, are present as ingredients of some of the other constituents of the herbal cough remedy, e . g . , camphorated opium tincture. The cinnamic acid peak is the only identified peak in the chromato- gram recorded at a wavelength of 254 nm, which is specific to tolu syrup. Additional evidence for the identity of the cinnamic acid peak is achieved by matching retention times and peak spectra to a reference cinnamic acid sample, with spectra recorded at the peak apices using the diode array detector (Fig.2). A i chromatogram have been identified. However, for this pur- pose they provide a recognisable fingerprint identification. Four of the larger peaks partially resolved from the main mass of peaks have very distinctive and complex ultraviolet spectra. The combination of matching peak retention times and ultraviolet spectra from the chromatograms of the herbal cough remedy and the ingredient is sufficient to identify the presence of wild cherry syrup in the product (Fig. 4). 90 0 - 210 260 310 360 Wavelengthlnm Fig. 4. Peak spectral identity for wild cherry syrup. Peaks A-D correspond to those in Fig. 3 Conclusion The HPLC assay method provides a simple technique to identify tolu and wild cherry syrups in the cough remedy. Further confirmation of the identity of the component peaks can be achieved in combination with diode array detection. 1 1 1 * 1 0 1 2 3 4 5 6 ’ 7 8 9 1 0 Ti me/m in I I Fig. 3. Peaks A-D correspond to those in Fig. 1 Chromatogram of wild cherry syrup recorded at 320 nm. Wild Cherry Syrup (Fig. 3) The peaks obtained from the wild cherry syrup ingredient elute within 4 min and are well resolved from the peaks attributed to tolu syrup in the combined mixture. None of the peaks in the References 1. “British Pharmacopoeia 1980,” HM Stationery Office, London, 2. Trease, G. E., “A Text Book of Pharmacognosy,” Sixth Edition, Baillibre, Tindall and Cox, London, 1952. 3. “British Herbal Pharmacopoeia 1976, 11,” British Herbal Medicine Association, Keighley, 1976, p. 159. 4. Harkirs, K. J., and Linley, P. A., “Determination of Balsamic Acids and Esters by GLC,” Analyst, 1973, 98, 819. p. 459. ROYAL SOCIETY OF CHEMISTRY: ANALYTICAL DIVISION ELECTROANALYTICAL GROUP INTERNATIONAL SYMPOSIUM ON ELECTROANALYSIS April Ilth-I4th, 1989 Loughborough The seventh International Symposium on Electroanalysis in Biomedical, Environmental and Industrial Sciences will be organised by the Electroanalytical Group in conjunction with the Electrochemistry Group of the Faraday Division. Further information is available from, and offers of contributions should be made to, Dr. A. G. Fogg, Chemistry Department, Loug hborough University of Technology, Loughborough, Leicester- shire LEI 1 3TU (Tel. 0509-222553).

ISSN:0144-557X    

DOI:10.1039/AP9882500158

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

165 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 Equipment News Atomic Absorption Spectrometer The Model 5100 PC offers a fully auto- mated multi-element system optimised for flame, furnace and mercury - hydride sampling. It will perform both conven- tional flame and furnace atomic absorp- tion as well as Zeeman-corrected graphite furnace analysis. The colour software works within a GEM environment and control of the instrument is via a mouse pointer and function keys. Drop-down menus and multiple windows providing between one and five simultaneous views into the system offer maximum versatility with peak performance. The 5100 PC system uses an IBM or fully compatible PC and includes a range of options and accessories to expand system capability. Perkin-Elmer Ltd. , Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA.Spectrophotometer The Series 6000 double-beam ultraviolet scanning spectrophotometers incorporate all the software required for multi-mode operation. Operation is simple without reference to menus, VDU displays or an instruction manual. Among the modes provided are 1st to 4th derivatives, super- imposed or sequential scans, difference have introduced new hardware, sample handling and result manipulation acces- sories for the PU8700. Pye Unicam Ltd., York Street, Cam- bridge CB12PX. Control Options for Spectrophotometr y A new range of Vectra PCs make MS- DOS control of the HP 8452A diode array ultraviolet - visible spectrophotometer significantly less expensive than before, bringing the flexibility and wide range of applications accessible with MS-DOS within the scope of most laboratory budgets. Hewlett-Packard Ltd., Miller House, The Ring, Bracknell, Berkshire RG12 1XN. Spectrometer The type JY 24 inductively coupled plasma spectrometer from Jobin Yvon is a compact, free-standing sequential model with a 0.64 m focal length monochroma- tor featuring a high speed, direct-drive mechanism enabling the spectral range 160-800 nm to be scanned in less than 10 s. There is a choice of JY blazed Master holographic gratings to suit the particular application, including an ion-etched grat- ing operating in the second order in the ultraviolet region. The JY 24 is suitable phosphorus, sulphur and other elements below 190 nm. Instruments S.A. - EDT Ltd., 14 Trad- ing Estate Road, London NWlO 7LU. Spectrometers Two new PlasmaQuad inductively coup- led plasma - mass spectrometers, the PQ2 and PQ2 Plus, are announced.Both feature the makers’ Quadrupole mass analyser and Multi-channel analyser, as well as an auto-analysis routine which enables optimisation on unknown sam- ples and specialised data output formats. The added power of the PQ2 Plus lies in its capability to provide time resolved data acquisition. VG Isotopes Ltd., Ion Path, Road Three, Winsford, Cheshire CW7 3BX. Gas Chromatograph The Model 92 gas chromatograph offers a choice of 5 high-performance detectors. The range comprises FID, ECD, NPO, FPD and TCD. Up to three detectors can be used simultaneously, with column out- let splitters available so that the column effluent can be distributed between detec- tors.The ionisation detectors are de- signed to be easily interchangeable and are mounted in low thermal mass ovens which heat up to operating temperature quickly. The TCD is mounted in a sepa- spectra, reaction kinetics, cell program- ming, wavelength programming, method and data storage and log absorbance scanning. An analysis mode includes curve and line fitting, multi-component analysis, absorbance ratioing, etc. Cecil Instruments Ltd., Milton Indus- trial Estate, Cambridge CB4 4AZ. Spectrophotometry Software A range of plug-in software for the mouse-driven PU8700 series of ultraviolet - visible spectrophotometers is announ- ced. Heading the list is a Multilambda package, which provides a whole suite of two and three wavelength calculations for sample analysis. For mixture analysis with known components the Multicomponent Analysis software automatically calcu- Jobin Yvon JY 24 inductively coupled plasma spectrometer lates the concentration of each constitu- ent.PU8700 Kinetics software has all the facilities for enzyme characterisation. In addition to the new software the makers for analysing complex matrices for major, minor and trace element concentrations. A nitrogen purge permits the analysis of rate dedicated oven to provide optimum thermal conditions. Analytical Measuring Systems, Shire-166 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 hill Industrial Estate, Shirehill, Saffron Walden, Essex CBll 3AQ. Gas Chromatograph The Shimadzu GC-14A is designed for capillary gas chromatography but is also compatible with packed columns.Up to four different sample injectors can be fitted and each can be independently temperature controlled, irrespective of conditions in the column or detector ovens. FID, ECD, FTD, TCD and FPD detectors can all be fitted. Designed for laboratory automation, the new instru- ment can be connected to a Shimadzu Chromatopac data processor. Connection to a C-R5A Chromatopac permits instant exchange of gas chromatograph and data processing parameters through the use of an IC card with 8 kbytes of RAM. Dyson Instruments Ltd., Hetton Lyons Industrial Estate, Hetton, Houghton le Spring DH5 ORH. Gas Chromatography Column The GS-Q column is a gas - solid open- tubular Megabore column designed to analyse light hydrocarbons, Freons, esters, sulphides, ketones and water up to 10 times faster than the conventional packed columns which it replaces, No cryogenic cooling is necessary.GS-Q columns are compatible with virtually all gas chromatographs and can be operated to conventional packed column flow- rates, temperatures and sample loads. A test chromatogram is provided with each column. J and W Scientific, 91 Blue Ravine Road, Folsom, CA 95630, USA. HPLC Columns The Ultracarb range of high carbon loaded CI8 (ODS) columns is available in 3 , 5 and 7 pm, with carbon loadings of 20 and 30%. HPLC Technology Ltd., Wellington House, Waterloo Street West, Maccles- field, Cheshire SKll 6PJ. HPLC Column The ChromSpher PAH column has been developed for the analysis of polycyclic aromatic hydrocarbons.It is a highly selective stationary phase which gives excellent separation of the 16 PAH prior- ity pollutants listed by the US Environ- mental Protection Agency. The 16 EPA priority pollutants can be separated in less than 20 min; only acenaphthene and fluorene need gradient elution. The other difficult pairs, benz(a)anthracene - chrysene and dibenzo(a, h)anthracene - benzo(ghi)perylene - indeno( 1,2,3 ,cd)py- rene, are base-line separated. A brochure is available. Chrompack UK Ltd., Unit 4, Indescon Court, Millharbour, London El4 9TN. Biocompatible Liquid Chromatography By using titanium and/or inert polymers for all mobile phase flow lines the Shim- adzu LC-7A liquid chromatography system is completely biocompatible and causes no lowering of physiological activi- ties in biological samples.The pump is resistant to buffer solutions with the high salt concentrations commonly used for the analysis of these samples. Also impor- tant for biological work is the excellent mixing provided by the LC-7A’s compact mixing chamber. This combined with the stability of the solvent delivery unit per- mits precise gradient elutions. For use with the new system are the SPD-7A ultraviolet and the SPD-7AV ultraviolet - visible spectrophotometric detectors, both with a maximum sensitivity of 0.001 AUFS and an autozeroing function mak- ing them ideal for trace analyses. Dyson Instruments Ltd., Hetton Lyons Industrial Estate, Hetton, Houghton le Spring DH5 ORH. Integrator for Chromatography The Chromatocorder 12 is a low-cost single-channel integrator compatible with any GC, LC, SFC or TLC.Although compact in design it incorporates an integral full-width printer - plotter. Remote control and long term power fail memory back-up are included as stan- dard. Severn Analytical Ltd, Unit 2B St. Francis Way, Shefford Industrial Park, Shefford, Bedfordshire SG17 5DZ. Chromatography Software ACCESS*CHROM is a multi-tasking, multi-user chromatography data handling system designed to operate on DEC VAX and MicroVAX I1 minicomputers. Not only does it have full-functionality soft- ware for chromatography data handling but it is also capable of acquiring data directly over Ethernet. It consists of seven comprehensive software packages to pro- vide chromatography method and sequence creation, data collection, re- integration and post-run data manipula- tion.It can support up to 64 direct terminal connections so that a variety of A to D interface terminals and printers can be configured with the system. Nelson Analytical Ltd., 860 Birchwood Boulevard, Birchwood, Warrington, Cheshire WA3 7QZ. Data Processors for Gas and Liquid Chromatography The Shimadzu C-R4A, C-R5A and C-R6A Chromatopacs can be interlinked or networked to other computers. The C-R4A is a menu-driven integrator using dual floppy disk drives for storage of chromatograms and/or instrument parameters and a standard system disk for operational programs. It offers real-time on-screen processing of chromatograms. The C-R5A is a single or dual channel integrator that allows data and files to be stored on IC cards.The C-R6A is a single-channel integrator for routine data processing. Dyson Instruments Ltd., Hetton Lyons Industrial Estate, Hetton, Houghton le Spring DH5 ORH. Chromatography Integrator The HP 3396A offers a full range of functions at low cost. It provides wide- ranging capabilities including storage and re-plotting of chromatograms, negative peak handling, ESTD% reporting, multi- level calibration, method storage and automation. A single integrated circuit board contains all system electronics, and the integrator can be used to control and implement a complete analysis and to generate and annotate reports. Hewlett-Packard Ltd., Miller House, The Ring, Bracknell, Berkshire RG12 1XN. Chromatography Data System The JCL6000 system is now expandable to accept inputs from two detectors on the same instrument.The expanded system retains the features of the single-channel system, allowing manual adjustment ofANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 167 base lines for both chromatograms. Mouse control is available as a standard expansion option. Jones Chromatography, New Road, Hengoed, Mid-Glamorgan CF8 8AU. HPLC Material for Preparative Chromatography Apex Prepsil, a high quality spherical material for preparative chromatography, is available in 8, 15 and 20 ym sizes as C8, CIS and plain silica. It is analogous to the 3, 5 and 10 pm Apex materials to allow easy scale-up from analytical to prepara- tive chromatography. The materials are available in bulk and prepacked in 1 in and Y2 in internal diameter columns. Jones Chromatography, New Road, Hengoed, Mid Glamorgan CF8 8AU.Gel Permeation Chromatography Columns The Phenogel range of GPC columns consists of 5 and 10 ym styrene - divinyl- benzene co-polymer based materials, in all sizes, including mixed bed gels for routine scouting. Phenogel is available in new analytical and preparative columns and can be re-packed with new media when the old packings are exhausted. Most GPC column materials can be regenerated at up to 60% off the cost of a new column. HPLC Technology Ltd. , Wellington House, Waterloo Street West, Maccles- field, Cheshire SKll 6PJ. resolution and sensitivity for monoclonal band detection, while the consistency with which specific monoclonal anti- bodies migrate simplifies visual identifica- tion. Beckman Ltd., Progress Roads, Sands Industrial Estate, High Wycombe, Buck- inghamshire.Protein Analysis Programs The capabilities of the makers’ Gene- Master DNA workstation have been expanded through the addition of protein analysis programs and the Protein Identi- fication Resource (PIR) database. The programs include such protein analysis tools as Chou-Fassman secondary struc- ture, hydrophobicity plots, reverse trans- lation, relative molecular mass, dot mat- rix and alignment. The PIR database can be accessed in less than 10 s by keyword, and protein sequences can be compared directly with the database. Bio-Rad Laboratories Ltd., Caxton Way, Watford Business Park, Watford, Hertfordshire WD1 8RP. Protein Concentration Kit The kit improves the sensitivity of sub- sequent analyses, purifying proteins from complex media and conserving expensive analytical reagents.It includes all the required reagents, filters and specific applications for concentrating or remov- ing proteins in volumes ranging from 1 to 1000 ml, and for concentrating antibodies on hydroxylapatite. Bib-Rad Laboratories Ltd., Caxton Refractive Index Detection Way, Watford Business Park, Watford, The Model 1755 refractive index monitor Hertfordshire WD1 gRp. offers accurate and reproducible detec- tion in the 20-50 ng Per Peak range. BY Ethidium Bromide Removal Kit Using a monochromatic, infrared LED The kit is based on column chromato- source, the Model 1755 provides good graphy with AG 5OW-X8 ion-exchange base-line stability and reduced base-line resin. The DNA is kept negatively noise.The response linearity and SenSitiV- charged by means of a Tris-HCl buffer, itY are d n n c e d through an optical design pH 8, and is thus repelled from the resin, that incorporates a beam splitter and dual passing through the column, while the silicon photodiodes. This allows the con- ethidium bromide is bound to the resin. centration of Peak components to be Bio-Rad Laboratories Ltd., Caxton measured by the differential index Way, Watford Business Park, Watford, between the Sample and the pure Solvent. Hertfordshire WD1 8Rp. Bio-Rad Laboratories Ltd., Caxton Way, Watford Business Park, Watford, Automated Enzyme Analysis An addition to the capability of the Hertfordshire WD1 8RP. Biomek 1000 automated laboratory work- Electrophoresis System for station is in the form of an enhancement Monoclonal Antibodies to the microtitre plate reading system.Developed as part of the makers’ Paragon The standard reading system measures agarose gel electrophoresis system kit optical density in the wavelength range range, the new method screens for mono- 400-700 nm. The latest option provides clonal antibodies before, during and after the extra benefits of ultraviolet illumina- each step of the purification process. tion and measurement at 340 nm. The Taking only 90 min, the process begins program looping feature of the Biomek with the application of the sample to the 1000 provides facilities for repeat readings pre-cast agarose gel. After electrophor- to be available at prescribed time intervals esis the operator dries and stains by using in order to determine kinetic reaction the kit of reagents, gels and sample rates.template applicator, which improves the Beckman Ltd., Progress Road, Sands traditional reproducibility of agarose gels. Industrial Estate, High Wycombe, Buck- Thin layer agarose gel provides sufficient inghamshire. Protein Analysis Protein I and Protein I1 are systems for separating, isolating and purifying proteins and they extend the capabilities of the makers’ Personal Chromatograph HPLC System Gold. System Gold Protein I is an isocratic chromatograph with a four-way solvent selection valve to enable programming of step changes in solvent composition. It makes protein isolations by fast affinity chromatography easy and it speeds size-exclusion chromatography.System Gold Protein I1 allows simple and programmable binary-gradient ion- exchange chromatography, which typic- ally is used in the purification of antibo- dies. It can also be used for additional IEC protein purification steps or in auto- mated clean-up procedures to dispose of excess non-eluting substances. Protein I1 can be used in hydrophobic interaction chromatography and reversed phase chromatography techniques. Beckman Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buck- inghamshire. Electrophoresis Densitometer The Shimadzu CS 9000 is suited to most types of densitometry, including thin- layer chromatography, electrophoresis, autoradiography and fluorescence appli- cations. A flying spot zig - zag scanning capability has been developed; this allows high accuracy in scanning large areas and it allows the instrument to perform 2-D contour mapping of the densitometer sample area.The basic instrument features a colour CRT, a high resolution parallel head printer - plotter and a monochromator by which the user can select any wavelength between 200 and 700 nm. A wide range of accessories is available, including two fluorescence attachments, one using a mercury lamp and the other a xenon lamp, a special 50 pm laser attachment, and slab and disc holders for wet gels. V. A. Howe and Co. Ltd., 12-14 St. Ann’s Crescent, London SW18 2LS. Drinking Water Analyser The Chrompack Packard drinking water analyser enables the determination of organic pollutants in water up to the p.p.b. or p.p.t. level.Developed by the maker, it was evaluated by the Nether- lands Waterworks Testing and Research Institute (KIWA). Chrompack UK Ltd., Unit 4, Indescon Court, Millharbour, London El4 9TN. Total Organic Carbon Analysis in Sea and Fresh Water By using new combustion techniques, which give carbon recovery rates close to loo%, the Shimadzu TOC-500 is capable of measuring down to 20 p.p.b., with analysis times being 2 min for total carbon and inorganic carbon. Volatile organic168 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 carbon can also be measured using an inexpensive option. With the addition of an automatic sample injector the TOC- 500 can be made into a fully automatic system. Designed to operate at reaction temperatures below 700 “C, the instru- ments avoid the problems associated with halides and sea water.Low boiling-point organic compounds can also be detected, as the evaporation chamber of the volatile organic carbon option is kept at 150°C. Data are processed by an integral micro- computer, with sample number, peak areas and coefficient of variation being printed out on a thermal printer - plotter. Dyson Instruments Ltd., Hetton Lyons Industrial Estate, Hetton, Houghton-le- Spring DH5 ORH. Mercury Analysis in Water, Urine or Soils The Jerome 511 mercury analyser can measure 3-100 ng of mercury without interferences, such as aromatic hydrocar- bons, sulphur dioxide or water vapour. Mercury vapour is reduced from the sample by using wet chemical procedures and is drawn into the instrument by an internal pump. The gold film sensor adsorbs and integrates the mercury vap- our, registering a proportional change in resistance which is digitally displayed in ng, no calibration curve being necessary.Arizona Instrument Corporation, P.O. Box 670, Cookham, Maidenhead, Berk- shire SL6 9BJ. pH - Conductivity Meter A portable, one-hand operated meter, measuring 159 by 32 by 57 mm, eliminates the need for sample taking. It features fold-away probes, which can be angled at 90” or 180°, allowing measurements to be taken at the most awkward angles. The C.P. Instrument Co. Ltd., P.O. Box 22, Bishops Stortford, Hertford- shire. pH and Conductivity Meters Two instruments have been added to the makers’ “Pocket” range. The Model 108 is a pH meter with automatic calibration; it recognises three standard NBS buffers (pH 4,7 and 10).The Model 109 is a dual range conductivity meter, offering a choice between 0-1999 pS and 0-19.99 mS readouts. Ciba Corning Diagnostics Ltd., Hal- stead, Essex C09 2DX. Titrators The DL21 is designed to handle large numbers of samples and is suitable for acid, base and redox titrations, non- aqueous or photometric titrations and also for determinations of surfactants and chlorides. It titrates automatically to two end-points or to equivalence points, and it determines p- and m-values, pH values, TAN/TBN values (total acid and total base numbers) according to ASTM/DIN, calculates half-neutralisation value (HNV) and carries out pH-stat and back titrations. The DL25, with built-in data- base of 15 standard methods, is suitable for both routine and development work.Where the standard methods do not exactly meet the user’s requirements, the methods can be adapted with configura- tion parameters entered in a dialogue with the DL25. These methods can then be stored in a special memory which will hold up to 50 methods. The makers’ balances can be connected for transferring sample weights automatically. Both titrators can be connected to various commercial dot matrix graphics printers or to the makers’ GA44 printer. Mettler Instrumente AG, CH-8606 Greifensee, Switzerland. Stirred Cell for Reclaiming Waste from Non-aqueous Solutions A new magnetically stirred cell uses sol- vent- and toxic chemical-resistant ultrafil- tration membranes in order to effect separations. Designed to handle non- aqueous solutions, the unit can reclaim wastes such as methyl ethyl ketone (MEK) that are used for cleaning indus- trial painting equipment.A SEPA-RG membrane was used to separate MEK and other solvents from paint waste. More than 30 SEPA membranes of various polymers and pore sizes are available. Osmonics Inc., 5951 Clearwater Drive, Minnetonka, Minnesota 55343, USA. Thermal Desorption Unit The TD4 is a new single-shot, two-stage desorption unit, ideal for the thermal desorption of organic vapours that have been adsorbed on to standard Perkin- Elmer type diffusive - pumped sampling tubes. It is also suitable for the thermal desorption of volatiles from a range of matrices not directly compatible with gas chromatography, such as solids, resins and emulsions. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA.Bench-top Furnace The BUCF 1700 Series is a compact, high speed, programmable chamber furnace designed for high temperature applica- tions. Available with a standard chamber size of 3.3 1, it offers rapid and precise temperature changes from ambient to 1700°C. It effectively replaces the mak- ers’ existing Ultraspeed 1700 furnace and is complemented by Ultraspeed 1700 ver- sions with 12.1 and 27 1 chamber sizes, which are manufactured with an integral mobile bench. Lenton Thermal Designs Ltd., 12-14 Fairfield Road, Market Harborough, Leicestershire LE16 9QQ. Ultracentrifuge Rotors The makers’ range of rotors has been extended by the addition of three new models. The VC-53 and the VC-50 are carbon fibre vertical models which com- plement the VTi-50, which is a titanium rotor.The VC-53 can spin eight 39-ml tubes at speeds up to 53000 rev min-1. The VC-50 can spin ten 39-ml tubes up to 50000 rev min-1. The third of the new rotors is the 50.4Ti, a titanium fixed angle model accommodating 44 6.5-ml tubes in two rows and spinning at up to 50 000 rev min-1. Beckman Ltd., Progress Road, Sands Industrial Estate, High Wycombe, Buck- inghamshire. Computer Control for Scanning Electron Microscope Specimen Stages The specimen handling capabilities of the makers’ scanning electron microscopes have been increased by the offer of optional external computer control for the motorised eucentric goniometer of the specimen stage. Pye Unicam Ltd., York Street, Cam- bridge CB1 2PX.Data Management System The Bactometer data management system is the first step in the development of a totally integrated laboratory informa- tion system (LIMS) which will eventually enable scientists to find the relationship between the various checks, such as pack weights, moisture content, pH, organo- leptic and chemical analysis, etc., to see the total picture and to become generally better informed. Results from the Bac- tometer can be automatically formatted and fed into LOTUS 123 software. Bactomatic Ltd., 1 Newtown Industrial Estate, Newtown Road, Henley-on- Thames, Oxfordshire RG9 1HG. Hose Clips The NPL series of screw clips uses a design of extreme simplicity with only three components to produce perfect circle clamping of high or low pressure hoses.Twelve sizes are available, from 9 to 23 mm outer diameter. Norma Products Ltd., Arnhem Road, Newbury, Berkshire RG14 5RU. Literature An 8-page “Sales Update” shows some of the latest products for gas chromato- graphy and HPLC. These range from capillary tubing and tube cutters to HPLC pressure gauges and thermal chart paper. A new Valco catalogue is also available. Thames Chromatography, 16 Raymead Court, Maidenhead, Berkshire SL6 8TN. “HPLC Applications in the Life Sciences” is a folder that brings together recent literature on the biochemical applicationsANALYTICAL PROCEEDINGS7 MAY 198, of HPLC in the life sciences. Three important illustrated application notes are included in the collection. The first describes peak purity control of human fibrinogen and its fibrinopeptides.The second covers the identification of the aromatic residues tryptophan, tyrosine and phenylalanine by derivative spec- troscopy. The third gives the makers’ findings on solvent recovery requirements for the separation of biomolecules. Also included is a brochure describing the MO AminoQuant amino-acid analyser. The publication is numbered 5954-6256. Hewlett-Packard Ltd., Miller House, The Ring, Bracknell, Berkshire RG12 1XN. A leaflet describes the latest version of VOL 25 the makers’ B4 colorimeter. The new version of the compact, lightweight, maidbattery portable instrument has four LEDs and covers 530-1000 nm. It is microprocessor controlled. Biotron Ltd., Church Lane, Bishop Thornton, Harrogate, North Yorkshire HG3 3JP. A brochure describes the new Chroma Series colorimeters and the accessories and consumables also available.Ciba Corning Diagnostics Ltd., Hal- stead, Essex C09 2DX. A brochure gives details of the AF7 two-speed coulometric Karl Fischer titra- tor. Previously sold under the Baird and Tatlock label, the complete range of 169 LTE’s Karl Fischer titrators will now be distributed by Roth Scientific. Roth Scientific Co. Ltd., Alpha House, Alexandra Road, Farnborough, Hamp- shire GU14 6BU. Perkin-Elmer have initiated the forma- tion of a User Group for their Laboratory Information Management and Chromato- graphy Laboratory Automation systems (LIMS 2000 and CLAS). Run jointly by the users and Perkin-Elmer, it is currently under the chairmanship of Dr. A. Wag- land from Roche Products Ltd.at Welwyn Garden City. Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Buckinghamshire HP9 1QA. Analytical Division Robert Boyle Medal in Analytical Chemistry At its meeting on February 17th, 1988, the Council of the Analytical Division accepted the recommendation of its Honours Committee to award posthumously the fourth Robert Boyle Medal in Analytical Chemistry to the late Professor E. Stahl, formerly of the University of Saarland. DIFFUSIVE AN ALTERNATIVE APPROACH TO WORKPLACE AIR MONITORING EDITED BY A BERLIN. R H BROWN. and K J SAUNDERS Hardcover SOOpp ISBN 0 85186 343 3 Price €45.00 $81.00 RSC Members Price €21.00 Diffusive Sampling is based on a symposium held in Luxembourg in September 1986 and organised jointly by the Commission of the European Communities and the United Kingdom Health and Safety Executive in cooperahon with the World Health Organization and the Royal Society of Chemistry. 0 Reviews the state of the art of diffusive sampler techniques 0 Stimulates the exchange of technical information 0 Assess the suitability and range of applications for workplace monitoring 0 Promotes the further development of this technique and its wider use. Orderinp: RSC Members should send their orders to The Royal Society of Chemistry. Membership Manager, 30 Russell Square, London WC1 B 5DT. U K Non-RSC members should send their orders to The Royal Society Letchworth, Herts SG6 1 HN, U K ROYAL lnforrnat on Services of Chemistry, Distnbution Centre, Blackhorse Road, THE QUEEN'S U N WE R S ITY OF BELFAST MSc COURSE in ANALYTICAL CHEMISTRY Applications are invited for admission to this established 12 month full-time MSc course which provides a comprehensive training in the theory and practice of modern chemical and instrumental methods of analysis. Applicants should normally possess an honours degree (or equivalent) in chemistry or cognate subjects. Part-time courses are available. The Science Research Council and the Dept. of Education Northern Ireland have recognised the course for tenure of their Advanced Course Studentships. A description booklet and application forms can be obtained from Professor D. Thorburn Burns, Dept. of Chemistry, Queen's University of Belfast, Belfast BT7 1 NN, Northern Ireland.

ISSN:0144-557X    

DOI:10.1039/AP9882500165

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

170 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 Publications Received Two-Dimensional NMR Spectroscopy. Applications for Chemists and Biochem- its. Edited by Willian R. Croasmun and Robert M. K. Carlson. Pp. xviii + 511. VCH. 1987. Price DM197. ISBN 0 89573 308 0. Laboratory Methods in Vibrational Spec- troscopy. Third Edition. Edited by H. A. Willis, J. H. Van der Maas and R. G. J. Miller. Pp. xviii + 600. Wiley. 1987. Price f55. ISBN 0 471 90343 4. Report of the Proceedings of the Nineteenth Session of the International Commission for Uniform Methods of Sugar Analysis Held in Cannes, 25-30 May 1986. ICUMSA. Pp. xxiv + 475. British Sugar Research Laboratories for ICUMSA. 1987. Price f28. ISBN 0 905003 11 X. Quality Assurance of Chemical Measure- ments. John Keenan Taylor. Pp.xxii + 328. Lewis Publishers. 1987. Price f47.60. ISBN 0 87371 097 5. Techniques in Electrochemistry, Corro- sion and Metal Finishing-A Handbook. Edited by Anselm T. Kuhn. Pp. xviii + 567. Wiley. 1987. Price f65. ISBN 0 471 91407 X. Einfuhrung in die HPLC. Rudolph E. Kaiser. Chromatographic Methoden. Pp. xiv + 256. Hiithig. 1987. Price DM96. ISBN 3 7785 1563 2. Advances in Standards and Methodology in Spectrophotometry. Edited by C. Burgess and K. D. Miclenz. Analytical Spectroscopy Library, Volume 2. Pp. xii + 403. Elsevier. 1987. ISBN 0 444 42880 1 (volume 2); 0 444 42695 7 (series). X-Ray Absorption Principles, Applica- tions, Techniques of EXAFS, SEXAFS and XANES. Edited by D. C. Koningsberger and R. Prins. Chemical Analysis, Volume 92. Pp. xiv + 673. Wiley. 1988. Price $77.50. ISBN 0 4'71 8'7547 3. Time-Resolved Vibrational Spectroscopy. Edited by George H. Atkinson. Pp. xviii + 417. Gordon and Breach. 1987. Price $89. ISBN 2 88124 191 3.

ISSN:0144-557X    

DOI:10.1039/AP988250170a

出版商:RSC    

年代:1988

数据来源: RSC

摘要:

174 ANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 Courses Training Courses at the Leatherhead Food be organised by Skandinavisk Teknikfor- RA medling International Ab, will run from May, 1988, Leatherhead June 2 4 and will be for those responsible for quality assurance and control pro- The following courses will be held in the grammes in geochemical, mining and near future. “The Use of Statistics in the metallurgical operations. The second control. The third (again June 3-4) will be of Meat Pies,” May 27. Further details of these courses are aimed at engineers and other technical available from the Leatherhead Food personnel who are concerned with the RA, Road, Leatherhead, selection or operation of fine grinding Surrey KT22 7RY. plant. For information contact Skandinavisk Food Industry,” May 23-25; “Meat Pro- (June 3-4) will be concerned with plant duct Manufacture ,” May 24-26; “Quality operating problems, optimisation and New Development of Pierre GY” Sampling Teknikformedling International Ab , Box Theory and Sampling Practice, APPlica- 205, 161 26 Bromma, Sweden.tion of Modelling and Simulation Tech- niques to Mineral Processing, and Air Classifiers: Principles of Operation and Flow Injection Analysis Performance Evaluation July 8-10, 1987, Loughborough June 2 4 , 1988, Stockholm, Sweden This residential course at the University The first of these courses, all of which will of Technology aims to explain the basic concepts of FIA, to review existing appli- cations, to illustrate its wide applicability with a variety of detectors and its unique advantages in on-line monitoring and control situations.Opportunity will be given to build and use simple systems, to investigate dispersion characteristics, and to gain confidence in using FIA systems. Several commercial manufacturers have offered systems for use. The course fee for residents will be 5305 (5280 if paid in advance). For further information contact Dr. Arnold Fogg, Chemistry Department, Loughborough University of Technology, Lough- borough, Leicestershire LEll 3TU. (Tel. 0509-222553 direct line.) The 1988 European Summer School on Major Hazards-the Preparation of Safety Cases July 25-29, 1988, CambridgeANALYTICAL PROCEEDINGS, MAY 1988, VOL 25 175 For the past few years IBC has run conferences on the changes which modern technology has generated in what is now called “high technology” industry.Throughout the world there is much public concern about the potential risks of large scale high technology industry, high- lighted from time to time by such events as Bhopal and Chernobyl. Control in Europe derives from an EEC Directive which itself owes much to the report of the Advisory Committee on Major Hazards, and is applied in the UK by the CIMAH Regulations. Plants covered by these Regulations will be required to prepare “Safety Cases” to be submitted to the Health and Safety Executive by July 8, 1989. If such cases are to be acceptable, much thought and skill will be needed in their preparation. The Summer School programme covers general aspects of major hazards covered in previous years, giving an essential background to the understanding and preparation of safety cases.Those who should attend will therefore include senior management responsible for pre- paring and submitting safety cases to the Health and Safety Executive. Local authority planers, emergency personnel and all those who need to develop their understanding of the problems associated with major hazard installations will benefit considerably. This year’s Summer School will be at Christ’s College, Cam- bridge. For further information please contact: Katie Lye, IBC Technical Services Ltd., Bath House (3rd Floor), 56 Holborn Viaduct. London EClA 2EX. Philips Analytical’s IR Summer School August 1-5, 1988, Cambridge The 27th Philips Analytical IR Summer School will take place in Cambridge.The only one of its kind in the UK, the school has become a popular annual event, attracting delegates from industrial, academic and governmental institutions worldwide. Open to students of all abili- ties, the School provides practical training on the latest infrared instruments, which this year will include Philips Analytical’s new, low-cost FTIR spectrophotometer. Instruction in sample handling and spec- tral interpretation will also be given, along with lectures and seminars on the theory and applications of both dispersive and Fourier transform IR analysis. Many of the sessions will be presented by visiting experts, including Dr. Archie Baker of the University of Glasgow and Peter Carter, Analytical Development Manager at Schering. Students and lectur- ers will stay at Queens’ College, Cam- bridge, for the duration of the course.The School’s language is English, and com- prehensive course notes and support materials are provided. Students wishing to enrol should con- tact Mrs. Ray Fullerton at Philips Scien- tific, Cambridge, on 0223-358866. Loughborough Short Courses September, 1988, Loughborough The following courses will be held in the Chemistry Department of the University of Technology. “Analytical Plasma Spec- trometry,” September 5-9, 1988, fee f450 including residence and all meals (f420 if paid in advance), non-residents f330 (f300 if paid in advance); “Atomic Absorption Spectrometry” (1-day up- date), September 12, 1988, fee f70 includes coffee, lunch and tea; “Modern Electroanalytical Methods,” September 14-16, 1988, fee f305 including residence and all meals (E280 if paid in advance), non-residents E235 (2210 if paid in advance); “Microcomputers in the Lab- oratory,” September 19-23, 1988, f450 including residence and all meals (E420 if paid in advance), non-residents f330 (2300 if paid in advance); “Supercritical Fluid Chromatography,” September 21- 23, 1988, fee f305 including residence and all meals (f280 if paid in advance), non-residents 223.5 (2210 if paid in advance).Further details are available from Mrs. J. Stirling, Department of Chemistry, Loughborough University of Technology, Loughborough, Leicestershire L E l l 3TU. The Leeds Course in Clinical Nutrition September 6-9, 1988, Leeds This course, and its associated exhibition, are organised by the Department of Medi- cine, St.James’s University Hospital and the Department of Adult and Continuing Education in the University. Both partici- pants and exhibitors should apply for further particulars to Mrs. H. L. Helme, Department of Adult and Continuing Education, The University, Leeds LS2 9JT. Continuing Education Courses September, 1988, Bradford A group of three post-experience courses will be held in Bradford in September, 1988. The courses are of three days duration each and are sponsored by the Institution of Chemical Engineers. A course on “Hydrocyclones” is to be held from September 13-15, a course on “Bulk Powder Testing” from September 20-24, and a course on “Particle Size Measurement and Sampling” from Sep- tember 26-28, 1988. All three courses are aimed at practising engineers or scientists, are pragmatically orientated and use com- puter-assisted teaching methods.After the successful introduction of the scheme last year, the course manuals for all three courses will again include a diskette with the software used on the respective courses (refer to the leaflets for details). The software alone is worth more than the registration fee and the courses are now even better value for money than before. For further information contact Dr. L. Svarovsky, Postgraduate School of Studies in Powder Technology, Univer- sity of Bradford, Bradford, West York- shire BD7 1DP. Microcomputers in the Laboratory September 19-23, 1988, Loughborough This residential course at the University of Technology covers a broad range of topics concerned with the operation, interfacing and applications of microcom- puters in scientific laboratories.Teaching methods include formal lectures, tutorials and practical sessions. Course members need only have a rudimentary knowledge of BASIC and an understanding of current, voltage, resistance and Ohm’s law. The course fee for residents is f450 (f420 if paid in advance). For further information contact: Dr. T. E. Edmonds, Chemistry Department, Loughborough University of Technology, Loughborough, Leicestershire LE11 3TU. 1988 European Seminar on Pressurised Storage of Flammable Liquids: Fire Prob- lems and Fire Protection October 24-26, 1988, London Large volumes of flammable gases are stored and transported as pressurised liquids (e.g., LNG, LPG or butane).Commerciallv, it is the ability to store. transport and process certain gases in liquid form which makes them attractive. However, from a safety viewpoint it is this which makes them so hazardous. Regula- tions and codes of practice prescribing precautions and procedures aimed at con- trolling the risk have consequently been framed. Methodologies have been devel- oped in parallel for assessing the hazards and risks posed. An integral part of this assessment is the need to utilise models and modelling techniques both to assess and predict the hazards and their conse- quences. Thus, a considerable amount of research effort, both nationally and inter- nationally, is being devoted to developing suitable models and validating them against acceptable experimental data, and to obtaining the necessary experimental data. The conference, organised by IBC Technical Services Ltd. in association with the Health and Safety Executive, will present an overview of the current state of the art and invites plant designers and operators, safety and loss prevention managers and engineers, members of regulatory bodies and researchers to attend. For further information please contact Katie Lye, IBC Technical Services Ltd., Bath House (3rd Floor), 56 Holborn Viaduct, London EClA 2EX.

ISSN:0144-557X    

DOI:10.1039/AP9882500174

出版商:RSC    

年代:1988

数据来源: RSC