摘要:

Proceedinas - - - -of the Analytical Division ofThe Chemical SocietyCONTENTS317 Summaries of Papers31 7 'Measurement of Fine Particles inthe Working Environment'320 ' P h ar maceu t ica I Analysis'336 Obituary337 Publications Received337 New British Standard338 Conferences and Meetings342 Analytical Division DiaryVolume 16 No 11 Pages 31 7-342 November 197PADSDZ 16(11) 317-342 (1979)I SSN 0306-1 396November 1979PROCEEDINGSOF THEANALYTICAL DIVISION OF THE CHEMICAL SOCIETYOfficers of the Analytical Divisionof The Chemical SocietyPresidentR. BelcherHon. SecretaryP. G . W. CobbHon. Treasurer Hon. Assistant SecretariesJ. K. Foreman D. I. Coornber. O.B.E.; D. C. M. Squirrel1Secretary Hon. Publicity and Public Relations Officer Editor, ProceedingsDr.A. Townshend, Department of Chemistry,University of Birmingham. Birmingham, B15 2TTMiss P. E. Hutchinson P. C. WestonProceedings is published by The Chemical Society.Editorial: The Director of Publications. The Chemical Society, Burlington House, London, W1 V OBN.Telephone 01 -734 9864. Telex 268001.Subscriptions (non-members) : The Chemical Society, Distribution Centre, Blackhorse Road,Letchworth, Hens., SG6 1 HN.Non-members can only be supplied with Proceedings as part of a combined subscription with The Analystand Analytical Abstracts.@ The Chemical Society 1979CHEMICAL SOCIETY ANALYTICAL DIVISIONEducation and Training Group Discussion Meetingand AGMto be held a tChelsea College, Manresa Road, London S.W.3December 19, 1979The theme of the meeting is "Educating Chemists for an AnalyticalProblem-solving Laboratory-Industry's Needs and Expectations," and thespeaker will be Mr. S. Greenfield.The meeting will start with the AGM at 6.00 p.m. and will conclude withdinner at 7.30 p.m. Senda cheque for f6, payable to Chelsea College, to Dr. E. J. Greenhow, Depart-ment of Chemistry, Chelsea College, to arrive not later than November 30th,1979.Dinner must be booked and paid for i n advance

ISSN:0306-1396    

DOI:10.1039/AD97916FX038

出版商:RSC    

年代:1979

数据来源: RSC

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November, 1979 ANALYTICAL DIVISION DIARY 341Analytical Division Diary, continuedDecember, continued“Impact on a Perfumery Company of theCosmetic Products Regulations,” by J . H.Mayo.“Analysis of Cosmetic Products for Legisla-tive Purposes,” by M. J. Glover.“Colouring Agents in Cosmetic Products,” byP. N. Clare.“Analytical Problems Related to the Cos-metic Directive-Manufacturer’s Point ofView,” by Mrs. D. M. Gabriel.Shirley Institute, Manchester.Thursday, 6th, 2 p.m.: London.Joint Pharmaceutical Analysis Croup on“Analytical Error. ”Pharmaceutical Society of Great Britain,1 Lambeth High Street, London, SE1 7JN.Friday, 7th, 2 p.m.: SuttonElectvoanalytical Group : Annual GeneralMeeting, followed by an Ordinary Meetingon “Electrochemistry in Cancer Research.”“Polarographic Analysis of Nitro-aromaticDrugs Used in Chemotherapy,” by M.R.Smyth.“Half-wave Potentials of Some Nitro-aromaticCompounds in Aqueous Solution and theirRelation to True One Electron ReductionPotentials Measured by the Pulse Radio-lysis Technique,” by P. O’Neill.“Estimation of Nitro-aromatic Drug Levelsin Tissue and Body Fluids Taken fromPatients and Experimental Animals inRadiosensitiser Drug Trials,” by R.Bugden.“Instrumental Techniques of Importance inMonitoring Chemotherapeutic Agents,” byJ. Burmicz.Institute of Cancer Research, Royal CancerHospital, Royal Marsden Hospital,Clifton Avenue, Sutton, Surrey.Wednesday, 12th, 2.30 p.m. : LondonAnalytical Division on “Analysis of Endo-genous Opiate Peptides.”“Biological Roles of Endogenous OpioidPeptides,” by Professor H.W. Kosterlitz.“Peptide Analysis,” by D. G. Smyth.Linnean Society Lecture Theatre, RurlingtonHouse, Piccadilly, London, W. 1.Thursday, 13th, 5 p.m.: BathWestevn Region.“Analytical Quality Control-Is it Worth allChemistry Department, The University,the Bother?” by A. L. Wilson.Bath.Thursday, 13th, 10 a.m.: LondonAutomatic Methods Group : Annual GeneralMeeting and Joint Meeting with the Indus-trial Analytical Instrumentation Group ofthe Institute of Measurement and Controlon “Dust Monitoring.”Speakers to include : S. Wallin, W. L. Snowsilland B. E. Prater.Scientific Societies Lecture Theatre, 23Savile Row, London, W. 1.Wednesday, 19th, 6 p.m.: LondonEducation and Tvaining Gvoup : AnnualGeneral Meeting, followed by a DiscussionMeeting.A discussion on “Educating Chemists for anAnalytical Problem Solving Laboratory-Industry’s Needs and Expectations,”introduced by S. Greenfield.Room N25, Chemistry Department, ChelseaCollege, Manresa Road, London, S.W.3NOVEMBERWednesday, 21st, 10.30 a.m.: BristolWestern Region and Atomic SpectroscopyGroup : current awareness Symposium on“Plasma Emission Spectroscopy.”Chemistry Department, The University,Bristol.Thursday, 22nd : HarlowEast Anglia Region : Annual General Meeting,followed by a meeting on “Analysis ofPolymers.” Speakers : G. Cheeseman andL. H. Ruddle.Revertex, Harlow.Thursday, 22nd, 4 p.m.: GlasgowScottish Region, jointly with the Glasgow andWest of Scotland Section of the CS and theAndersonian Chemical Society.“Optoacoustic Spectroscopy,” by G.F.Kirkbright.Room C133, Chemistry Department, Uni-versity of Strathclyde, Cathedral Street,Glasgow, G1 1XLWednesday, 28th, 6.30 p.m. : LondonMicrochemical Methods Group.A discussion on ‘Polarography-Does itStill Work?” introduced by R. C. Rooney.The Savoy Tavern, Savoy Street, London,w.c.2.Thursday, 29th, 6.30 p.m. : LondonBiological Methods Group : Annual GeneralMeeting, followed by a meeting on “Bio-logical Considerations in the Improvementof the River Thames and its Catchment.”Speakers: Sir John Hanbury and M. J.Andrews. Burlington House, Piccadilly,London, W.l.Friday, 30th, 5 p.m.: CardiffWestern Region, jointly with the South East“Affinity Chromatography,” by 1’. Dean.University of Wales Institute of Science andWales Section of the CS.Technology, Cardiff.DECEMBERWednesday, 5th, 2p.m. : SheffieldAtomic Spectroscopy Group : Annual GeneralMeeting, followed by a Joint Meeting withthe North East Region on “CompetitiveSpectroscopies in Metallurgical Analysis. ”“The Role of Condensed Arc EmissionSpectrochemical Analysis,” by L. Kidman.Analytical Division DiaryPrinted by Heffers Printers Ltd Cambridge England“The Glow Discharge Lamp and its Operationand Applications,” by A. Butterworth.“Metallurgical Applications of X-ray Fluor-escence Spectrometry,” by R. A. White.“Is There a Place for the ICP in MetallurgicalAnalysis?” by L. C.Ebdon.City Polytechnic, Pond Street, Sheffield.Wednesday, 5th, 2.15 p.m.: LondonParticle Size Analysis Group : Annual GeneralMeeting; 2.15 p.m. Chromatography andElectrophoresis Group : Annual GeneralMeeting; 2.30 p.m. 2.45 p.m. JointMeeting of above Groups on “Hydro-dynamic Chromatography. ’’“Recent Developments in the Chromato-graphy of Biochemicals and Biopolymers,”by E. A. Hill.“Developments in Hydrodynamic Chromato-graphy and its Use in Particle Sizing,”by R. Maley and J . Oliver.“A Hard-sphere Model System for HDCPreparation and Properties of UniformSilica Spheres,” by S. M. F. Tavernier.Linnean Society Lecture Room, BurlingtonHouse, Piccadilly, London, W. 1.Wednesday, 5th, 10.45 a.m. : LondonSpecial Technqiues Group : Annual GeneralMeeting, followed by an Ordinary Meetingon “Recent Developments and i4pplicationsof Infrared Analysis.”“Applications of Fourier Transform InfraredSpectroscopy,” by Professor N. Sheppard.“Laser Electric and Magnetic ResonanceSpectroscopy,” by G. Daxbury.“Some Aspects of Optoacoustic Spectrometryin the Infrared Region,” by B. C. Beadle.“Infrared Spectrometry of PolymerSurfaces,” by H. Willis.“-ipplications of IR to CharacterisingMinerals and Inorganic Materials,” byV. C. Farmer.“Data Handling by Computer in IR Spectro-scopy,” by F. E. Dunston.“IR Detectors for Liquid Flow Analysis,”by S. Day.Read Lecture Theatre, Sherfield Building,Imperial College, South Kensington,London, S.W.7.Wednesday, 5th, 1.30 p.m. : ManchesterNovth West Region, jointly with Associationof Public Analysts, on “The Analysis ofCosmetic Products.”[continued inside back cove

ISSN:0306-1396    

DOI:10.1039/AD97916BX040

出版商:RSC    

年代:1979

数据来源: RSC

摘要:

Vol. 16 No. 11 November 1979 Proceedings of the Analytical Division of the Chemical Society Measurement of Fine Particles in the Working Environment The following is a summary of one of the papers presented at a meeting of the Particle Size Analysis Group held on March 28th, 1979, at the University of Leeds. 317 Aspects of Particulate Monitoring in the Ambient Atmosphere D. J. Ball EizvironwzentaE Sciences Group, Scienti’c Branch, Greater London Council, County Hall, London, SE 1 7PB Many of the techniques for monitoring particulates in the external environment, including those most widely used, are, by any terms of reference, rudimentary.There are a number of reasons for this. For example, in situations where surveillance of large areas is required it is necessary that the apparatus should be simple to operate and that it should produce reliable results, even when run by different personnel, some of whom might be non-technical. Other requirements, such as ease of installation, infrequent maintenance and low cost, may also be important.Nonetheless, simplicity in monitoring does not imply that the interpretation of data will be straightforward and often it may be necessary to conduct parallel studies in support of the main programme, especially in the light of changing environmental circum- stances or even new legal requirements.This short paper describes some of these monitoring methods with the emphasis, where applicable, on factors affecting data interpretation. These are the high-volume gravimetric method,132 widely used in the United States, Canada and Japan, and the smoke- stain t e c h n i q ~ e , ~ , ~ which is more associated with Europe.The former is based upon the collection of a weighable deposit on an 8 x 10 in glass-fibre filter-paper. In order to obtain an adequate deposit within the usual sampling period of 24 h, air is drawn through the filter at a high speed, 1.5-2.0 m3 min-l, and hence the apparatus is known widely as a Hivol sam- pler.The smoke-stain technique is different, and dispenses even with the need to weigh filters! Here, air is drawn through a 1 in diameter Whatman No. 1 filter-paper over a 24 h period, with a flow of approximately 2 m3 d-I. The darkness of the resulting stain is then measured with a reflectometer and this reading converted into an equivalent concentration, expressed in pgm-3, of “equivalent international standard smoke,” by means of an inter- national standard calibration c u r ~ e .~ ? ~ The resulting reading is intended to provide an approximate indication of the dark material in the air, material that is mainly a product of combustion, and that is thought to be an important element of pollution.In the United States a network of Hivol samplers has been in operation for some years under the auspices of the Environmental Protection Agency (EPA), and the data from these sites is used to test compliance with the US air quality standard for particulates. However, in some areas the validity of the Hivol method for testing compliance with what is essentially a health protection standard has been contested on the grounds that the technique was designed to collect the total suspended particulate, defined as all particles up to 100 pm in size, and not just the smaller, respirable fraction.It is likely that factors such as these will be taken account of in the EPA’s current review of particulate monitoring, and that a new air quality standard will be set for inhaled particulates6 In contributing to their review, the EPA’s Health Effects Research Laboratory has recommended that a standard for inhalable particles should include all particles up to 15 pm aerodynamic equivalent diameter,7 which represents 317 Of the techniques in use for regional surveys, two predominate.318 MEASUREMENT OF FINE PARTICLES Proc.AnaZyt. Dia.Chem. SOC. particles depositing in the conducting airway as well as in the gas exchange areas of the respiratory system. In support of this recommendation the EPA’s Environmental Monitoring and Support Laboratory is now working on a four-year plan to establish 300 sites for monitoring inhaled particulates in the USA.6 Although the sampling technique for the inhaled particulate net- work has yet to be perfected, a number of options are available. The least expensive of these options is to modify the existing Hivol sampler with a new air inlet designed to have a 15 uni cut-off (Fig.1 ) . Alternatively, several instrument manufacturers have produced dichotomous samplers, which separate particles into smaller than 2.5 pm and 2.5-15 pm ranges (Fig. 2). These would meet a second recommendation of the Health Effects Research Laboratory, namely that particles smaller than 2.5 pm be collected separately.Fractionation baffles rm-x ,!.::leefr Air Air ‘‘Eiter tan::: HiVol sampler 1 Flow 1 H Fig. 1 . Hivol sampler with 15 p111 size selective inlet. Fractionating inlet ( 1 5 pm) Air flow Acceleration nozzle Fractionation zone Collection nozzle 0 0 Coarse Fine particle particle filter filter Fig.2. Dichotomous particulate sampler. Firstly, there is extensive evidence that not only are two modes usually observed in the mass or volume distribution of well-mixed urban and rural aerosols, but that the fine and coarse modes are normally quite different in chemical compo~ition.~ This is because the two modes have different origins.The fine one is largely formed by chemical reaction in the atmosphere and subsequent condensation - coagula- tion processes, whereas the coarse one owes its origin mainly to mechanical processes. Cascade impactor studies suggest 1-3 um as the most appropriate range for selecting a dividing line between fine and coarse aerosols. The second point is that, from health considerations, it may be important to distinguish between those particulates depositing largely in the conducting airway and those in the gas-exchange areas of the lung, and this has lead to the recommenda- tion of 2.5 pm as being the best dividing line for this p ~ r p o s e .~ While it is not envisaged that a revised air quality standard would require both of these measurements, the data, together with chemical analyses of the deposits, would be an important aid in source identification in locations failing to meet the standard, and in support of epidemiological studies.Apart from these considerations a number of sampling problems still need to be resolved. One, for example, concerns the formation of artifact sulphates and nitrates on glass-fibre filters during sampling, which adds to the mass determination.Another concerns the general problem of establishing quality-assurance practices for aerosol monitoring, which are generally far inferior to those available for gaseous monitoring.6 In Britain, the smoke-shade technique has been widely deployed under the auspices of the National Survey of Air Poll~tion.~ The purpose of this survey has been primarily to measure the progress of the Clean Air Act, but the emphasis could change if proposed legislation on the introduction of air quality standards by the European Comniunity* were to be ratified.In this instance, the National Survey technique might be used to test for compliance. This use could pose problems because not all member countries use the smoke-stain method, some rely- ing upon various types of gravimetric measurement.As was reported earlier,g there is no simple relationship between the two types of measurement; this fact is exemplified by simul- taneous 24 h gravimetric and smoke-stain measurements in London, which have varied by factors of from 6 to 1 to 0.3 to 1, depending upon the time and location of measurement. In The reason for this separation is basically two-fold.November, 1979 MEASUREMENT OF FINE PARTICLES 319 Leeds, still larger ratios have been noted.1° There are a number of reasons for these variations.One is that the equivalent international standard smoke (eiss) used to interpret the reflectance data is, for many areas, no longer representative of the main constituents of the ambient particulate matter.This is not unexpected because, since the designation of the eiss, there have been substantial changes in the origins and types of atmospheric particulates. In Britain, for example, there has been a rapid decline in coal burning, formerly a major source of particulates, while other particulates, such as ammonium sulphate, which are believed to be formed by photochemical oxidation of sulphur dioxide, have been found to be on the increasell and now constitute the major mass fraction of the aerosol. Further, the sensitivity of the smoke-shade method to black particulates means that the reflectance readings obtained are highly dependent upon the proximity of the monitoring site to motor vehicles,12 which, in modern communities, are always present to some degree.Whether or not these problems can be resolved remains to be seen, but it is unlikely that a solution can easily be reached where the choice of monitoring technique may affect the apparent need for, and hence the cost of, pollu- tion abatement measures. A further important factor, which does nothing to simplify matters, is that many of the epidemiological studies upon which health protection standards are being based were carried Heavy metal survey 1 2 3 Fig.3. Results from a heavy mctal survey in London using moss bags.14 The histograms show deposition rates from recovered moss bags (in ng d-l).320 PHARMACEUTICAL ANALYSIS Proc. Analyt. Div. Chem. soc. out some years ago when ambient particulates were quite different from those of today.Thus, irrespective of the continuity of standardised monitoring practices, the reported results may be quite divorced in significance from those of some years ago, and their associated health effects. Apart from a few special studies, other types of particulate monitor, nephelometers, ,!3- absorption, piezoelectric monitors, etc., have found little application in area surveys because of their cost and operational requirements.However, in view of the recent interest in heavy metals, it is worthwhile to add a few words on the moss-bag technique, which does not suffer from these deficiencies. Extensive studies have shown that natural moss, especially certain species of Sphagnum, can accumulate heavy metals from the air with high efficiency.13 In conducting a survey of airborne heavy metals the usual approach is to place 10-15 g of cleaned, unpolluted moss in nylon mesh bags, and expose them at the sites in question for periods of about 1 month.After collection the bags are dried, digested in acid, and the heavy metal content determined by atomic-absorption spectrophotometry. Fig. 3 shows results from one such survey in London.14 Clearly, low cost and ease of installation, especially as no on-site power-supply is required, are important assets.However, because of the known sensitivity of metal on moss deposition rates to wind-run and also particle size,15 the quantitative value of the data needs to be viewed with caution. A preferable approach may be to use moss bags as qualitative indicators, and then follow up in any areas found to be suspect with a more quantita- tive gravimetric sampler.The author thanks the Scientific Adviser to the GLC, Mr K. T. Kelly, for permission to publish this paper. The opinions expressed are those of the author and not necessarily those of the Council. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. References Jutze, G. A., and Foster, K .E., J . Air Pollut. Control Ass., 1967, 17, 17. U.S. Environ. Prot. Agency, Fedl. Registev, 1971, 36, (84), 8190. “Methods of Measuring Air Pollution,” Publ. No. 17913, OECD, 1964, 15. Ministry o f Technology, “National Survey of Smoke and Sulphur Dioxide, Instruction Manual,” HM Stationery Office, 1966. British Standard 1747: Part 2 : 1964. Rodes, C., Envivon. Sci. Technol., 1978, 12, 1353. Miller, F. J., Gardner, D. E., Graham, J . A., Lee, K. E., Wilson, Mi. E., and Bachmann, J . D., “Size Considerations for Establishing a Standard for lnhalcd Particles,” United States Environmental Protection Agency, 1979. Off. J . Ezw. Commun., 1976, C54, 79. Ball, D. J . , Pvoc. Analyt. Div. Chew. Soc., 1977, 14, 203. Clarke, A. G., personal communication. Salmon, L., Atkins, D. H. F., Fisher, E. M. R., Healy, C., and Law, D. V., Sci. Tot. Envivo$z., 1978, 9, Ball, L). J . , and Hume, R., Atunos. Environ., 1977, 11, 1065. Goodman, G. T., and Roberts, T. M., Nature, 1971, 231, 287. Muskett, C. J . , Envivon. Hltla, 1976, 84, 267. Clough, W. S., UKAEA Havmcll Report, 1974, M2612. 161.

ISSN:0306-1396    

DOI:10.1039/AD9791600317

出版商:RSC    

年代:1979

数据来源: RSC

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320 PHARMACEUTICAL ANALYSIS Proc. Analyt. Div. Chem. SOC. Pharmaceutical Analysis The following are summaries of six of the papers presented at a meeting of the Joint Pharma- cuetical Analysis Group held on May loth, 1979, at the Pharmaceutical Society of Great Britain, London. Rapid Microbiological Assay for Tiamulin in Animal Feeds Based on the Measurement of pH R. F. Cosgrove and G. T.Jones Squibb Institute for Medical Research, Reeds L a n e , iWoreton, Wirral, iWcvscyside, L46 1Q W Tiamulin is derived from the naturally occurring antibiotic pleuromutilin, which is produced by the fungus Plczcrotzbs mutilis. It is a semi-synthetic antibiotic, which is relatively stable,November, 1979 PHARMACEUTICAL ANALYSIS 321 crystalline and water soluble, it possesses activity against Gram-positive bacteria, myco- plasmas and certain spirochaetes and it is used in veterinary medicine, particularly for the treatment of swine pneumonia and dysentery.The determination of tiamulin in medicated pig feeds by chemical means proved proble- matical and a microbiological assay was therefore required. Antibiotics in animal feeds are notoriously difficult to assay : long extraction procedures are often required, interferences from feed components can be many and varied, and it can be difficult to obtain truly representative samples of feed simply because of the mixture of large numbers of components with greatly differing particle sizes and densities.Classical microbiological assays suffer from a number of disadvantages , two important ones being the variability of results and the relatively long incubation periods required for the organism to elicit its response.Rapid and automated methods, many based on the measure- ment of physico-chemical parameters rather than the measurement of growth or no growth, have much to contribute to speeding up and improving microbiological assays. However, many of these methods can suffer from similar problems of reliability and reproducibility.In our own laboratory, variation in results from microbiological assays of all types has been considerably reduced in recent years largely as a result of the use of constant sources of inocula from liquid nitrogen storage. The latter provides a source of microbial cells that can be used over a number of years and that have known responses to particular antibiotics.Such inocula have been widely used for agar diffusion and turbidimetric assays and also for preservative efficacy testing-l Bacteria, yeasts and moulds have all been stored for up to 4 years without any detectable loss of viability. A typical rapid assay method was the procedure reported 11 years ago for kanamycin and gentamicin, which was based on the change in pH caused by a rapidly metabolising organism.2 The ready availability of a reliable inoculum and the much improved pH meters and electrodes now available offer considerable scope for the further development of this type of assay. Thus, the assay of tiamulin by measuring pH change seemed a rational approach. Extraction of the active ingredient from the animal feed produced considerable problems in itself and is the subject of a forthcoming publication.The microorganism used for the conven- tional agar diffusion assay for tiamulin is Stafihylococcus aureus, which was also found to be suitable for the pH method, and is easily and successfully stored in liquid nitrogen by con- trolled cooling in the vapour phase followed by direct immersion in the liquid.1 A variety of growth media were examined and tryptone soya broth was found to be the most suitable and reliable.Commercially available tryptone soya broth has dibasic potassium phosphate in- corporated as a buffer and for the pH assay the broth obviously has to be formulated without this addition. To investigate the effects of cell numbers and time on the rate of pH change the cryogenically stored inoculum was diluted to three concentrations and incubated with a range of tiamulin concentrations for 3, 4 and 5 h.The response of the organism was found to be dependent on the length of incubation and the cell concentration used as a starting inoculum and the conditions that gave a straight-line response after incubation for 5 h were selected for the assay.The sensitivity of the pH method is such that a large dilution of the extract is possible in the growth medium, which both removes any stimulating effect that the feed may have on the growth of the organism and also prevents it causing a change in pH per se. A variety of feeds were examined for their effect on the assay system and none was found to have a significant effect.Nevertheless, as a precaution, the standards used in the assay are diluted in an extract from non-medicated feed so that feed extract and solvent levels in both standards and samples are identical. The standard is diluted to five concentrations of tiamulin, whereas the sample is extracted and diluted to two levels approximating concentrations either side of the mid-concentration of the standard.A 0.1-ml volume of each solution is diluted in triplicate with 9.9ml of inoculated broth and incubated at 37 "C for 5 h. The pH of the medium in each tube is then determined and a graph plotted of standard tiamulin concentration against pH. The sample concentration is then determined from the graph. Assays on feed samples at 120,30 and 10 p.p.m. of tiamulin are within 6% of theory and the 95% confidence interval for eight individual determinations is less than 55%.These results compare favourably with those obtained using the conventional agar diffusion assay.322 PHARMACEUTICAL ANALYSIS PYOC. Analyt. Div. Chem. SOC. The method has also been applied successfully to the determination of tylosin in animal feeds and to the assay of various cephalosporins both as raw materials and in formulated products. We see no reason why the method should not be applied to the assay of many other antibiotics.References 1. 2. Cosgrove, R. F., J . Ass. 08. Analyt. Cham., 1979, 62, 1188. Faine, S., and Knight, D. C., Lancet, 1968, 375. Rapid Development of a High-performance Liquid Chromatographic Assay for 4-Aminopyridine in Body Fluids D.K. Scott Pharmacy Department, East Birmingham Hospital. and University of Aston in Birmingham, Gosta Green, Birmingham, B 4 7ET The release of a novel drug for use in humans is normally preceded by a lengthy series of tests and studies on its physical properties, formulation and biological activity. Much will be known about its behaviour and a good assay will have been developed.Rarely, however, a relatively untested drug may be used in an emergency and a reliable assay may not be avail- able. Such was the case in the outbreak of botulism in Birmingham in August, 1978. Botulism, which is fortunately rare in Great Britain, is caused by the bacterium Clostridium botulinum, which releases a potent, but heat-labile, neurotoxin.Most outbreaks are associated with inefficient home canning and bottling of meat and fruit (notably in Canada and Northern USA) and rarely in commercial products, owing to their more efficient heat treatment. The nature and consequences of the Birmingham outbreak have been reported e1sewhere.l The prime cause of illness (and death) in botulism is not the bacterial infection but the action of the toxin, which prevents the release of acetylcholine from peripheral nerve terminals and so prevents muscle contraction.This blockade is non-reversible but may be overcome by the proliferative regeneration, over several months, of the nerve terminals. It is necessary to support neuromuscular function during this period of regeneration and extensive physio- therapy combined with artificial ventilation is employed.This treatment, however, may not be sufficient to ensure survival and it was decided in this incident to employ a drug, 4-amino- pyridine (4-AP), that is known to have desirable properties in other species.2 In particular there was no information available about blood levels or pharmacokinetic properties, and samples were therefore taken during prolonged intravenous administration of 4-AP and an assay service was requested by the physician.A knowledge of the blood levels attained was considered especi- ally important in view of certain adverse reactions experienced by some of these patients in addition to the undoubted beneficial effects on muscle performance. The only published work involving assays of PAP utilised either direct ultraviolet or fluorescence spectrometry3 or potentiometric t i t r a t i ~ n , ~ none of which were suitable for use in biological samples.No high-performance liquid chromatographic (HPLC) or gas-chromato- graphic (GC) assay had been published and we therefore set out to develop an HPLC assay (we subsequently heard of an unpublished GC assay developed in the University of Groningen using a Carbowax 20M column with 27, potassium hydroxide solution and a nitrogen detec- tors).4-AP has a low fluorescence quantum yield and requires excitation at wavelengths less than 220 nm (below the range of our commercial detectors), but has a high ultraviolet extinction coefficient at approximately 260nm in aqueous solution. In the final mobile phase the maximum absorption was at 268 nm with a logarithmic molar extinction coefficient of 4.15.It was found that 4-AP was soluble in aqueous and alcoholic solutions but only very sparingly soluble in alkanes, which suggested that a reversed-phase separation with a metha- nol - water eluting agent should be suitable. A 25 cm x 4.6 mm i.d. stainless-steel column packed with 5-pm Spherisorb RP-18 (Anachem) was used, with a Pye LC3 reciprocating pump and a Pye LC3 ultraviolet detector.Under such conditions 4-AP eluted as a broad, low-intensity band with a long retention time. Lowering of the pH, to ionise the 4-AP and make it less lipophilic, by the addition of Very little was known about the drug’s properties in humans. For detection a choice of ultraviolet or fluorescence detectors was available.November, 1979 PHARMACEUTICAL ANALYSIS 323 acetic acid resulted in even broader and more dilute bands, contrary to expectation.Use of acetonitrile in place of methanol resulted in longer retention times. As normal-phase separa- tions would prove difficult in view of the poor solubility of 4-AP in non-polar solvents, and ion- exchange columns were considered too difficult to stabilise for the rapid development that was required, an ion-pair system was tried.To acetonitrile - water mixtures (in various proportions) were added various amounts of orthophosphoric acid (to ionise the 4-AP) and sodium dodecylsulphate (SDS) to act as a counter ion. The final eluting agent (0.001 5 M SDS, 1% V/V orthophosphoric acid and 40% V/V acetonitrile in distilled water) resulted in a narrow, symmetrical and intense peak equivalent to approximately 1500 theoretical plates after 8.5 min.Reducing the acid or SDS concentrations resulted in a loss of symmetry and reproducibility, probably due to incomplete ion pairing. Replacing acetonitrile with the less toxic methanol also resulted in a broader peak.Extraction of 4-AP from serum and urine was achieved by precipitating the proteins, centrifuging and injecting 100 pl of the supernatant fluid on to the column via a Specac valve injector. The only suitable precipitating agents available were dimethylformamide and 2-methyl- propan-1-01. As the former gave a better extraction efficiency it was preferred, and two volumes of dimethylformamide were added to each volume of serum, and one volume to each volume of urine.Because of the intense absorption of dimethylformamide and other serum constituents it was not possible to include an internal standard, but it was not necessary as repeated injections of extracts from spiked serum varied in peak height by less than 1 mm (the variation was not rigorously determined because of the time constraints). This technique yielded a linear calibration graph passing through the origin when using the spiked serum, but when compared with saline solutions of identical strength gave only a 46% yield.It was found, by extracting a given sample twice in succession and comparing resultant peak heights, that 98% of the available 4-AP was being extracted, suggesting that some 4-AP was irreversibly thrown down with the protein components of the serum.As the method was reproducible, and time was of the essence, the results were accepted. Neither the other drugs used in therapy nor the patient’s serum constituents interfered with the 4-AP peak. I t was found that after 40-50 samples had been examined the back-pressure increased significantly and, to counteract the change in flow-rate (inherent in the LC3 system), stan- dards were run between pairs of samples. The minimum detection limit was approximately 20 ng ml-l in serum using 0.4 ml of serum (the maximum available).The serum profiles and urine results are shown in Fig. 1 and Table I, respectively. Timelmin (from start of infusion) 0-30 30-60 60-90 90-120 120-150 150-180 180-210 2 10-240 TABLE I URINE EXCRETION DATA 4-AP concentration in urine/pg ml-1 Patient 1 5.4 41.2 119.2 110.0 105.2 103.5 81.2 88.2 1 Patient 2 4.7 29.0 133.3 298.7 247.2 288.0 253.3 - Serum levels were found to be very low (35-315 ng ml-l) but exhibited the typical profile of Urine levels were comparatively high (5-300 pg ml-l), due It is not possible, from the data available, to Unpublished results from the University of Groningen5 using the GC method showed good This Thus an adequate assay was developed, using only the facilities available in a hospital a multi-compartmental drug.mostly to the low volume of urine output. estimate the percentage renal excretion or the metabolism (if any). agreement on serum levels but poor agreement (much lower levels) on urine samples.may be due to difficulty apparently encountered in their extraction procedure. pharmacy, within 48 h.324 500 c - E 400 0-J C C 0 -.. .- 4- P 300 4- K u K 0 E 200 % n e d 100 3 0 PHARMACEUTICAL ANALYSIS PYOC. AnaZyt. Div. Chem. SOC. 30 mg bolus Patient B: duration of infusion a t 15 mg h-’ -- - - - - - - _ _ - - - - - -- -- - - - - - - - - - - - __ - X I 1 j \,;patient B I \ X I 1 I 2 3 4 Tirne/h Fig.1. 4-AP serum concentration uersus time profiles. References 1. 2. 3. 4. 5. Evenhuis, J., personal communication. Ball, A. P., et al., Q. J Z Med., 1979, in the press. Lundh, H., Leander, S., and Thesleff, S., J. Neurol. Sci., 1977, 32, 29. Babiak, S., and Testa, A. C., J . Phys. Chern., 1976, 80, 1882. Gracza-Lukacs, M., Szasz, G., and Buda, L., GydgyszerLszet, 1976, 20, 93.High-performance Liquid Chromatographic Separation of Anti- biotics and Antibacterials Kay R. Bagon Laboratory of the Government Chemist, Cornwall House, Stamford Street, London, SEL 9NQ Antibiotics are commonly assayed by microbiological techniques when a suitable chemical method has not been found or when the sensitivity of such a method has been shown to be inadequate.However, microbiological analysis is of limited specificity ; in many instances, similar antibiotics and their decomposition products cannot be distinguished from each other and hence the chemical purity of the compound cannot be ascertained. Microbiological analysis is also extremely time consuming and the results are subject to statistical confidence limits.In general, antibiotics are not sufficiently volatile or thermally stable to be suitable for analysis by gas - liquid chromatography. Gas-chromatographic methods used for chlor- amphenicol, tetracyclines and sulphanilamides involve derivatisation and extraction pro- cedures that are too time consuming to be of use for routine analysis. High-performance liquid chromatography (HPLC) is capable of rapidly, selectively and accurately determining many antibiotics and the method can be used to supplement results obtained by the microbiological testing of potency, or even to replace it.However, many of the published HPLC methods for antibiotics are suitable only for the analysis of the pure compound, rather than of antibiotics in pharmaceutical preparations, which limits their application.This paper describes some applications of HPLC to the analysis of formulated antibiotics products. A preliminary account has appeared e1sewhere.l Most separations can be performed by using a reversed-phase octadecylsilane (ODS) column, as the retention time of a compound can be considerably influenced by the addition of a salt to an aqueous methanol mobile phase. By adjusting the pH, good separations can beNovember, 1979 PHARMACEUTICAL ANALYSIS 325 achieved.(The mechanism is complex but is thought to involve both weak cation exchange of the unsilanised surface silanol groups on the column and ion-pair partition.) In all instances the samples, which are mainly in the form of injections, tablets or creams, are simply extracted into a suitable solvent (the mobile phase itself if possible) and injected directly on to the column, hence minimising clean-up procedures.With the advent of microparticulate bonded phases, the chromatographic separation required can usually be achieved in less than 5 min. As the specificity of assay relies on the separation by the column, relatively non-specific absorp- tion wavelengths of 212 nm and lower can be used for those antibiotics which do not show strong enough absorption maxima in other regions of the ultraviolet spectrum.One of the main advantages of HPLC is the speed of assay. Experiment a1 A Waters 6000A constant-volume pump and a Cecil 212 variable-wavelength ultraviolet spectrophotometer with an 8-p1 flow cell were used.The injection was a stop-flow system. The columns were 150 x 4.6 mm i.d. stainless steel, slurry-packed in methanol at 5000 lb in-2 (34 MPa) using a Haskel constant-pressure pump. For column packing, Spherisorb S5-ODS (Phase Separations Ltd.) was used for reversed-phase separations and the strong cation- exchange (SCX) column was prepared from Spherisorb S5W silica gel by the method described by Cox et aL2 The different mobile phases and pH values employed are indicated in the legends to the figures and have been summarised previous1y.l Retention times for some specific drugs have also been published e1sewhere.l Applications Chloramphenicol An unlicensed sample of 15% aqueous chloramphenicol injection, for treatment of bacterial infections in animals, was assayed by reversed-phase HPLC after diluting 1 ml to 500 ml with methanol - water (60 + 40) and injecting 2 p1 on to the column.It can be clearly seen from the chroinatogram (Fig. 1) that the sample has almost completely degraded to 2-amino-1-(4- nitrophenyl)propane-1,3-diol, of which 5.2% was present. Only 0.36% of chloramphenicol was found, so that the injection would be useless and potentially dangerous to use.Separation of chloramphenicol and its degradation products was achieved within 4 min. Erythromycin Erythromycin usually contains erythromycins A, B and C, of which erythromycin A is the major component and the most potent antimicrobial agent. A 50-mg amount of the sample was weighed into a centrifuge tube and extracted,with 10 ml of methanol. A 2 - 4 portion, centrifugally clarified, was then assayed by reversed-phase HPLC.The erythromycin was clearly separated from the excipient and the mean of three assays showed the sample to contain 620.6 I.U. mg-l, with good reproducibility. A sample of erythromycin lactobionate powder for injection was analysed. Tyrothricin Tyrothricin is an antimicrobial mixture of polypeptides, containing 60% of tyrocidins A, B and C and 20-25% of gramicidins.When a solution of tyrothricin was injected on to the reversed-phase column it was found to produce seven peaks. Whenever an antibiotic consists of a mixture of compounds with different biological activities, HPLC is of use in determining the relative amounts of each component. When standard materials from two different sources were compared, it was found that the amounts of their constituent components varied considerably (see Fig.2). A sample of mouth ulcer tablets was crushed and 1 g was extracted with 10 ml of 80 + 20 methanol - water in an ultrasonic bath for 15 min. It was then centrifugally clarified. Clearly, as the quantitation is based on the peak height of the major polypeptide peak, the sample must be compared with a standard of the exact tyrothricin material as supplied by the tablet manufacturer.If the tyrothricin content had been expressed in International Units, then the manufacturer’s standard would have had to have been microbiologically assayed against the recognised International standard. However, in this instance the sample was326 I PHARMACEUTICAL ANALYSIS i Proc.Analyt. Div. Ckem. SOC. 8 6 4 2 0 Time/rnin Fig. 1. Chromatogram of degraded chloram- phenjcoI injection. Column : Spherisorb ODs. Mobile phase: 0.01 M ammonium formate - methanol (45 + 55), pH 5.4. Flow-rate: 1.0 ml min-l. Detection: UV a t 278 nm, x 0.1 a.u.f.s. Peaks: 1 = 4-nitrobenzoic acid; 2 = chloramphenicol ; 3 = 4-nitrobenzaldehyde ; and 4 = 2-amino-l- (4-nitrophenyl)propane-l,3-diol. 1 O I I 1 0 8 6 4 2 0 Time/min 8 6 4 2 0 Fig.2 . Chromatograms of tyrothricin: (?) extract of mouth ulcer tablets; (b) manufacturers standard : and (c) reference standard. Column: Spherisorb ODs. Mobile phase: methanol - water (85 + 15). Detection: UV at 212 nm, x 0.02 a.u.f.s. stated to contain 1.Og of tyrothricin per tablet and this was confirmed by comparing the heights of the major peaks in the sample and the manufacturer’s standard.Nys tatin A similar situation arises with nystatin, which is a tetraene antifungal agent used to treat candidiasis and similar infections. Microbiological assay of nystatin indicated that reference materials obtained from different sources varied in potency.The findings were confirmed by reversed-phase HPLC, which showed that the reference materials differed in the amounts of their major polyene components. Ideally, in order to express the potency of such an anti- biotic, each peak should be related to a pure standard of that isolated component, the potency of which should be determined microbiologically. The assay should then be the sum of the components, not expressed chemically as a mass percentage but expressed biologically in activity units.In this instance the sample to be analysed consisted of nystatin tablets, which were crushed and 25 mg extracted with 100 ml of methanol - 0.05 M ammonium formate buffer. As with tyrothricin it is essential to compare the sample with the manufacturer’s own production material.The result obtained from this assay did, in fact, compare satisfactorily with that found by microbiological assay. Procaine Penicillin The sample, in the form of a cream to be used on cows to treat streptococcal mastitis, nominally contained 300 000 I.U. of penicillin per 5-g tube. A 0.5-g amount was weighed into a 150-ml conical flask and extracted with 100 ml of methanol - water in an ultrasonic bath for 15 min and for a further 30 min on a shaker. A 2-pl volume of the clear solution was then injected on to the reversed-phase column.Both the penicillin peak and the procaine peak (retention times 2.6 and 3.6 min, respectively) can be assayed simultaneously by comparison with a suitable standard. The same system has been used in this laboratory to identify and assay other p-lactams, such as cephalexin, methicillin, benzylpenicillin and phenoxymethyl- penici1lin.lNovember, 1979 PHARMACEUTICAL ANALYSIS 327 Streptomycin The sample consisted of a nominally 25% aqueous injection of streptomycin for veterinary use.Although streptomycin does not absorb ultraviolet radiation above 210nm, it can be conveniently monitored using an ultraviolet detector set at a low non-specific wavelength, such as 204 nm or below.Tetracycline Tetracycline reference standard normally contains about 4% of the 4-epimer, which is almost inactive, and consequently even the “pure” standard has only 96% purity. Epimerisa- tion occurs faster at pH 2-6.3 If tetracycline is exposed to heat, for example during ~torage,~ it degrades to form anhydrotetracycline and 4-epianhydrotetracycline.The latter compound is extremely toxic and the allowed limit is equivalent to 0.5% m/m of the tetracycline itself. It is therefore important for accuracy of assay and reasons of safety to be able to separate the components chromatographically rather than to accept a microbiological assay that expresses only the over-all potency.Fig. 3 shows a sample of tetracycline 5% injection to be badly degraded. For analysis, the sample was simply diluted with water (1 ml to 100 ml) and 2 pl were injected on to the SCX column. This injection was calculated to contain 1% of epian- hydrotetracycline, 2% of anhydrotetracycline, 1 yo of epitetracycline and 2.3% of tetracycline itself. The presence of EDTA in the mobile phase is necessary in order to prevent the tetracycline forming a chelate with the stainless-steel column. Many of the methods for the HPLC of tetracyclines use a phosphate b ~ f f e r ~ ~ ~ in the mobile phase.However, in this laboratory the use of sodium dihydrogen orthophosphate as buffer was found to cause the pump to become blocked, owing to the tendency of the phosphate to crystallise out of the methanol - water phase.Although it is possible to run tetracycline on an ODS (reversed-phase) column using methanol and orthophosphoric acid at pH 2.5, very poor results are obtained with tailing peaks and incomplete resolution. Also, the acidity of the mobile phase may itself lead to further degradation of the tetracycline. Sulphanilamides Sulphanilamides are not antibiotics in the strict sense, but they have antibacterial activity and are often administered in combination with antibiotics such as penicillin or streptomycin.A sample of tablets containing 135 mg of sulphamerazine and 185 mg of both sulphadiazine and sulphathiazole was assayed, It was crushed and 200 mg were extracted with 100 ml of 0.1 N sodium hydroxide solution.The solution was filtered and 2 p1 were injected on to the reversed-phase column after suitable dilution. Fig. 4 illustrates that complex sulphanilamide mixtures can be readily separated on the ODS column. Levels as low as 1 pg ml-l can be accurately determined. Ni trof urans The nitrofurans are a distinct class of antibacterial compounds, unrelated to the antibiotics or the sulphanilamides : their action is bactericidal rather than bacteriostatic.One such preparation consisted of an oily base containing furazolidone and nitrofurazone at levels of 150 mg each, suspended in 3 g of base, used as an intra-mammary injection to treat cows against mastitis. Nitrofurazone is almost insoluble in water, whereas furazolidone is almost insoluble in both water and methanol.However, it was found that the ointment could be almost completely dissolved in acetone. A 0.5-g amount of sample was extracted with 100 ml of acetone in a conical flask placed for 15 min in the ultrasonic bath and 2 pl of the solution were then injected on to the reversed- phase column. It was found1 that the two compounds gave a very clean separation, with retention times of 3.2 min for nitrofurazone and 4.0 min for furazolidone.Levels as low as 5 pg ml-l could be easily determined. It was directly assayed after dilution 1 to 50 with water. The more soluble ammonium formate was found to be a more satisfactory buffer. Conclusion It has been demonstrated that HPLC can be used routinely for the analysis of many dif- When the antibacterial is produced in a pure form (e.g., ferent antibiotic preparations.328 PHARMACEUTICAL ANALYSIS Proc.Analyt. Div. Chem. SOC. penicillins, tetracyclines and sulphanilamides) an HPLC assay gives a fast , accurate analysis and allows impurities to be detected. However, when the antibiotic is a mixture, it is far more difficult to relate the various component peaks to the actual potency of the antibiotic, and thus express the total biological activity of the substance. 22 b 20 18 16 1 4 1 2 1 0 8 6 4 2 0 Tirne/min Fig.3. Chromatogram of degraded tetra- cycline injection. Column : LiChrosorb SCX. Mobile phase: methanol - 0.02 M Na,EDTA + 0.05 M ammonium formate (30 + 70), pH 5.8. Detection: UV a t 270nm, x 0.1 a.u.f.s. Peaks: 1 = oxytetracycline; 2 = tetracycline; 3 = epitetracycline ; 4 = anhydrotetracycline ; and 5 = epianhydrotetracycline.1 3 1 0 8 6 4 2 0 Timehin Fig. 4. Chromatogram of mixed sulphanil- amides. Column : Spherisorb ODs. Mobile phase: 0.01 M ammonium formate - methanol (65 + 35), pH 6.b. Flow-rate: 0.5 ml min-l. Detection: UV at 370 nm, x 0.2 a.u.f .s. Peaks: 1 = sulphamethizole; 2 = sulphaguanidine; 3 = sulphadiazine; 4 = sulphathiazole; 5 = sulphamerazine ; 6 = sulphapyridine; and 7 = sulphadimidine.Several hundred injections have been made on the columns without appreciable losses in sensitivity or separating power. The methods involve minimum clean-up procedures and separation times of less than 5 min are achieved in many instances, allowing rapid, specific and accurate determinations to be made.Reproducibility of assay was satisfactory and relative standard deviations of less than 4% were achieved. The author thanks Miss Shahida Harnid for her technical assistance, Mr. G. F. Phillips for advice and encouragement and the Government Chemist for permission to publish this paper. References 1. 2. 3. 4. 5. 6. Bagon, K. R., J . High Resolution Chromat., 1979, 2, 211.Cox, G. B., Loscombe, C. R., Slucutt, M. J., Sugden, K., and Upfield, J. A., J . Chromat., 1976, 117, McCormick, J. R. D., Fox, S. M., Smith, L. L., Bitler, B. A., Reichenthal, J., Origoni, V. E., Muller, Walton, V. C., Howlett, M. R., and Selzer, G. B., J . Pharm. Sci., 1970, 59, 1160. Tsuji, K., Robertson, J. M., and Beyer, W. F., Analyt. Chem., 1974, 46, 539. Bailey, F., J .Chromat., 1976, 122, 73. 269. W. H., Winterbottom, R., and Doerschuk, A. P., J . Am. Chem. SOG., 1957, 79, 2849.November, 1979 PHARMACEUTICAL ANALYSIS Activity, Assay and Stereochemical Integrity of Tricyclic Neuro- leptics 329 W. J. Irwin and A. Li Wan Po Department of Pharmacy, University of Aston in Birmingham, Gosta Green, Birmingham, B4 VET Tranquillisers and antidepressants play an important role in current medical practice. One important group is based on the thioxanthene nucleus and the combination of an exocyclic olefinic function and a 2-substituent (which makes the tricyclic residue asymmetric about the double bond) in these drugs allows the existence of geometrical isomers.Cis forms (alterna- tively named a- or 2-), in which Rl and R, are on the same side of the double bond, and trans forms (p- or E-), in which the substituents are on opposite sides, may be isolated.Fig. 1 shows the structures of drugs available in the UK that have been found particularly useful in the treatment of schizophrenia and allied di~orders.l-~ cis Z ci trans PE n Thiothixene -S02N(CH3)2 -(CH2)2-N N-CH, u cis Z H X tram E Fig. 1.Geometrical isomers of tricyclic neuroleptics. Flupenthixol, as the proprietary Depixol and Fluanxol, is perhaps the drug of choice. This has a low sedative - hypnogenic potency and a high therapeutic index, which allows prescription in very low dosages. It has also achieved some notoriety through its use in the treatment of violent inmates of institutions.330 PHARMACEUTICAL ANALYSIS Proc.Analyt. Div. Chem. SOC. The original stereochemical assignments were based on dipole moment and refractive index measurements4 but subsequent X-ray crystallographic studies have shown that the conclu- sions were in e r r ~ r . ~ - ~ Care should therefore be exercised in reading early literature in this field. Indeed, one current authoritative sourceg refers to chlorprothixene, a very early example of these compounds, as the a-form but also describes this incorrectly as the trans- isomer.A rapid lH nuclear magnetic resonance spectroscopic method for the establishment of stereochemistry based on paramagnetic shift reagents is now available.lO Fig. 1 also includes doxepin and dothiepin, which exhibit geometrical isomerism by virtue of the asymmetry caused by the hetero atom substituted into the ethano-bridge of amitriptyline.Pharmacological Activity Structure - activity relationships of tricyclic neuroleptics are an intensively studied field.ll~l2 The existence of geometrical isomers in the tliioxanthene series prompts the question , “Are pharmacological differences between these isomers apparent ?” Table I gives in viuo and in vitro13 data that indicate that this is indeed so.Pre-treatment of the test animal with tranquilliser was found to protect against a drug-induced stereotyped response (in rats apomorphine induces a gnawing response whereas amphetamine produces movements of the head and fore-paws). The cis-isomer is considerably more potent than the trans-isomer in these tests. One such test is based on the competition for dopamine receptor sites in the brain (a possible mode of action for these compounds).The adenyl cyclase activity in homogenates of rat-brain corpus striatum, which is sensitive to the presence of dopamine, may be inhibited by the addition of a tranquilliser that competes with dopamine for receptor sites. The inhibition constants (Ki) show that here, too, the &-isomers are the more potent.Thiothixene is apparently much less active in the test than the other thioxanthenes, probably because an equilibrium mixture (37% cis14) was used in this instance. Other tests, such as competitive binding studies,15J6 inhibition of platelet aggrega- tionl’ and prolactin secretion,l* confirm this trend. Although clinical evidence is not to hand to permit the certain extension of these results to human therapy,lg correlations between daily clinical dose and in vitro effect for various neuroleptics have been established20 and there seems little doubt that substantial differences between the therapeutic efficiency of the isomers would be expected.21 Less information is available for doxepin and dothiepin but it has been shown that analogous results hold and that cis-doxepin is more active than the trans-isomer.22 In view of this variation in activity, it is instructive to examine the composition of solid dosage forms of these drugs (Table 11) and to note the lack of standardisation in this field.In vitro tests confirm this difference. TABLE I I N VZVO AND IN VZTRO ACTIVITY OF THIOXANTHENE GEOMETRICAL ISOMERS Ki = ICb0/ 1 + - : IC,, = concentration of drug required to produce 50% inhibition of dopamine- stimulated increase in adenylate cyclase activity; S = concentration of dopamine added; and K , = Michaelis constant (the concentration of dopamine required for half maximum activation of the enzyme).( €3 Antagonism of apomorphine stereotopy, Component ED,o/mg kl3-l 2-Flupenthixol .. .. .. .. 0.3 E-Flupenthixol .. .. .. > 80.0 2-Chlorprothixene . . .. .. E-Chlorprothixene . . I . . _ Chlorpromazine . . .. . . Thiothixene . . .. .. .. Antagonism of Antagonism of amphetamine dopamine-sensitive stereotopy, adenyl cyclase ED,,/mg kg-l activity, K~IM > 160.0 >5.0 x 0.07 1.0 x 10-9 9.5 x 10-7 1.7 x 10-7 3.7 x 10-8 4.8 x Analysis Although manufacturers are keenly aware of this variation in activity and monitor their products closely, little regard has been paid to isomeric composition by many workers.One reason is undoubtedly that assay methods23 for the isomers have been tedious and prone toNovember, 1979 PHARMACEUTICAL ANALYSIS 331 TABLE I1 PERCENTAGE OF MORE ACTIVE &-ISOMER IN TRICYCLIC NEUROLEPTICS Percentage of Compound cis-isomer Chlorprothixene .. . . . . . . 100 Clopen thixol . . . . .. . . 45 Dothiepin . . .. . . .. . . 5 Doxepin . . .. . . . . . . 15 Flupenthixol . . .. .. . . . . 50 Thiothixene . . . . . . . . .. 100 error. Quantitative analysis has been performed by paper chromatography followed by ultraviolet spectroscopy on the extracted spots.14 Many other chromatographic methods have failed to separate isomer^.^^-^^ It is surprising that although an official test for the composition of doxepin is available2' and a gas - liquid chromatographic method for the detection of isomers of metabolites in body fluids has been described,2s papers describing high- performance liquid chromatographic (HPLC) analysis have failed to describe the separation of the second c o m p ~ n e n t .~ ~ * ~ ~ The HPLC of thiothixene has also been described, but again detection of only one isomer was reported.31 In addition to these methods an infrared assay has also been described.32 In view of these observations, a rapid, reliable assay to permit the study of isomers was clearly required. Circular high-performance thin-layer chromatography on silica enabled the rapid (less than 2 min) separation of the isomers to be achieved33 (e.g., clopenthixol: Z-, R, = 0.47 ; E-, R, = 0.31 ; ethanol - benzene - water, 20 + 20 + 1).HPLC on silica using ethyl acetate - methanol - 3% ammonia solution (85 + 15 + 1) as the mobile phase was found to quantify the composition reliably.34 In each instance the cis-isomer was eluted first (Table 111).Promazine was included as an internal standard and the calibration graph was con- structed using a solution containing a constant amount of drug composed of various propor- tions of cis- and trans-isomers. For the quantification of Depixol tablets (3 mg) calibration was undertaken using 0.3 mg ml-l solutions. Typical plots were as follows: Y ~ ~ ~ , ~ ~ = 294.8(&4.2)~ + 0.8 ycis = 415.8(&5.3)~ - 0.9 r2 = 99.8yo, n = 11 y2 = 99.9yo, n = 11 where c mg ml-l is concentration. TABLE I11 RETENTION DATA FOR GEOMETRICAL ISOMERS OF TRICYCLIC NEUROLEPTICS Retention timelmin (-*-, Resolu- Compound czs trans tion Chlorprothixene .. . . 6.04 8.22 2.42 Clopenthixol . . . . 8.02 8.89 1.09 Dothiepin . . .. . . 8.54 9.05 0.99 Doxepin .... . . 8.84 9.66 1.03 Flupenthixol . . . . 7.09 8.05 1.28 Bulk samples of flupenthixol assayed in this way showed the presence of 46.7(*1.4)y0 (batch 1) and 44.0( &0.12) % (batch 2) of the more active cis-isomer. With tablets, however, problems were encountered if complete extraction of the drug was not achieved. Extraction into water (10 ml) showed an apparent proportion of the cis-isomer of 51.3% based on a 91.7% recovery.Almost complete recovery of flupenthixol was obtained with 1 M hydrochloric acid (10ml) and the true cis level was found to be 48.9(&0.15)y0. It appears that differential adsorption of the isomers on to the tablet excipients takes place and, unless complete extrac- tion is ensured, no reliance can be placed on measured isomer ratios.The smaller Fluanxol tablets (0.5 mg) were even more difficult to extract and each tablet required 1 M hydrochloric acid (10 ml) for reliable levels (47.9 & 0.24%) to be obtained. It is also noteworthy that the difference between 'the higher tablet figure (48.9%) and the lower batch value (44.0%)332 PHARMACEUTICAL ANALYSIS PYOC. Analyt. Div. Chem. SOC. approaches a critical level (about 10%) if this is reflected in the variation between other formulated samples.Stereochemical Integrity A possible cause of concern in this situation is whether pathways exist for the inter- conversion of cis and trans forms, particularly with those drugs which are formulated as a single isomer. Although prolonged heat treatment initiates slow degradation of fl~penthixol,~~ we have shown that when separate solutions of the 2 and E forms are autoclaved (115 “C, 30 min) no degradation or isomerisation is detected. To overcome problems associated with variable daylight intensity, a Microscal light fastness tester was used to simulate irradiation at a power rated at 3.4 times that of daylight.Samples were in aqueous solution (0.5 mg ml-l) held in clear glass ampoules.(i) Irradiation of the Z- or E- isomer of a thioxanthene stored under nitrogen rapidly yields a photoequilibrium mixture of both cis and trans forms, and only with flupenthixol is this similar to the formulated composi- tion. (ii) Further irradiation yields a single new component (e.g., flupenthixol, retention time 6.3 min). This undergoes rapid degradation on attempted isolation to yield 2-trifluoromethyl- thioxanthone and l-hydroxyethylpiperazine. The single peak obtained for this component suggests that either no olefinic residue remains in this product or, more probably, that one isomer is now significantly more stable thermodynamically.A possible structure is an enamine obtained by migration of the double bond down the aliphatic chain. (iii) A third degradation route is observed in solutions stored in air.These rapidly undergo photo- chemical oxidation to yield 2-trifluoromethylthioxanthone. This instability has been noted previ0usly.~~.~7 Doxepin and dothiepin appear to be significantly more stable. The observations noted here do not relate to solid dosage forms, which are stable even under high-intensity illumination. However, if solutions of these drugs are handled during prepara- tion, analysis or other fields of study, adequate precautions to avoid photochemical degradation should be taken.One such instance may be flupenthixol decanoate, used to prolong duration of action, and formulated in an oily i n j e c t i ~ n ~ * , ~ ~ as the &-isomer. A less satisfactory situation pertains, however, when solutions are exposed to lighL36 Three main degradation routes can be identified, as follows.Conclusion There is much evidence to suggest considerable differences between the pharmacological properties of thioxanthene isomers. Batch to batch variations are possible and also routes to establish equilibria or degradation pathways exist in solution.In view of this and the availability of assay methods it seems timely to highlight these properties for the benefit of pharmacists and analysts. In addition, there appear to be demonstrable differences in the physico-chemical properties of these isomers. It has been stated that there is no variation in the distribution of metabolism of doxepin isomers,40 but it would seem that such s t u d i e ~ ~ l , ~ ~ on thioxanthene neuroleptics using the specificity afforded by current HPLC procedures would repay interest.1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. References Merller Nielsen, I., Pedersen, V., Nymark, M., Franck, K. F., Boeck, V., Fjallard, B., and Christensen, Weissman, A., Adv. Biochem. Psychopharmac., 1974, 9, 471. Kaiser, C., Pavloff, A. M., Garvey, E., Fowler, P.J., Tedeschi, D. H., and Zirkle, C. L., J . Med. Chem., Petersen, P. V., and Mraller Nielsen, I., in Gordon, M., Editor, “Psychopharmacological Agents I,” Schaeffer, J. P., Chem. Commun., 1967, 743. Post, M. L., Kennard, O., and Horn, A. S., Acta Crystallogr., 1974, B30, 1644. Post, M. L., Kennard, O., Sheldrick, G. M., and Horn, A. S., Acta Crystallogr., 1975, B31, 2366.Post, M. L., Kennard, O., and Horn, A. S., Acta Crystallogr., 1975, B31, 2724. Windholz, M., Editor, “Merck Index,” Merck, Sharp and Dohme Ltd., Hoddesdon, 1976, p. 281. Kaiser, C., Warren, R. J., and Zirkle, C . L., J . Med. Chem., 1974, 17, 131. Horn, A. S., Post, M. L., and Kennard, O., J . Pharm. Pharmac.. 1975, 27, 553. Tollenaere, J. P., Moereels, M., and Koch, M.H. J., Eur. J . Med. Chem., 1977, 12, 199. A. V., Acta Phannac. Tox., 1973, 33, 353. 1972, 15, 665. Academic Press, New York, London, 1964, pp. 301-324.November, 1979 PHARMACEUTICAL ANALYSIS 333 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40. 41. 42. Miller, R. J., Horn, A. S., and Iversen, L. L., Molec. Pharmac., 1974, 10, 759.Muren, J. F., and Bloom, B. M., J . Med. Chem., 1970, 13, 17. Enna, S. J., Bennett, J. P., Burt, D. R., Creese, I., and Snyder, S. H., Nature, Lond., 1976, 263, 338. Burt, D. R., Creese, I., and Snyder, S. H., Molec. Pharmac., 1976, 12, 800. Bouillon, D. J., Grimes, R. P. J., and Orr, M. W., BY. J . Pharmac., 1975, 55, 555. Meltzer, H. Y., Paul, S. M., and Feng, Y.S., Psychopharmacology, 1977, 51, 181. Crow, T. J., Deakin, J. W. R., and Johnstone, F. L., Nature, Lond., 1977, 267, 183. Seeman, P., and Lee, T., Science, N . Y . , 1975, 188, 1217. Enna, S. J., Bennett, J. P., Burt, D. R., Creese, I., U’Prichard, D. C., Greenberg, D. A., and Snyder, Bloom, B. M., and Tretter, J. R., Belg. Pat., 641,498, 1964; Chem. Abstr., 1966, 64, 719c. Rudy, B. C., and Senkowski, B.Z., in Florey, K., Editor, “Analytical Profiles of Drug Substances,” Dell, H.-D., Fiedler, J., and Teichgraber, R., 2. Analyt. Chem., 1970, 249, 41. Dell, H.-D., Fiedler, J., and Kamp, R., 2. Analyt. Chem., 1971, 253, 357-360. de Leenheer, A., J . Chromat., 1973, 17, 339. “British Pharmacopoeia 1973: Addendum 1975,” HM Stationery Office, London, 1975, p.16. Rosseel, M. T., Bogaert, M. G., and Claey, M., J . Pharm. Sci., 1978, 67, 802. Vandemark, F. L., Adams, R. F., and Schmidt, G. J., Clin. Chem., 1978, 24, 87. Uges, D. R. A., and Bouma, P., Pharm. Weekbl., Scient. E d n , 1979, 1, 45. Wong, C. K., Cohen, D. M., and Munnelly, K. P., J . Pharm. Sci., 1976, 65, 1090. Uda, Y., Mizuta, E., and Yashiki, T., J . Takeda Res. Lab., 1970, 29, 701.Li Wan Po, A., and Irwin, W. J., J . High Resolution Chromat., submitted for publication. Li Wan Po, A., and Irwin, W. J., J . Pharm. Pharmac., 1979, 31, 512. Enever, R. P., Li Wan Po, A., and Shotton, E., J . Pharm. Sci., 1979, 68, 169. Li Wan Po, A., and Irwin, W. J., J . Pharm. Pharmac., 1979, in the press. Gantes, P., Barat, J., and Joly, H., Annls Pharm. Fr., 1969, 27, 645.Jarrgensen, A., and Gottfries, C. G., Psychopharmacologia, 1972, 27, 1. Nymark, M., Franck, K. F., Pedersen, V., Boeck, V., and Merller Nielsen, I., Acta Pharmac. Tox., 1973, Hobbs, D. C., Biochem. Pharmac., 1969, 18, 1941. Jerrgensen, A., Hansen, V., Dahl Larsen, U., and Khan, A. R., Acta Pharmac. Tox., 1969, 27, 301. Jargensen, A,, Fredericsson Overer, K., and Hansen, V., Acta Pharmac.Tox., 1969, 27, 339. S . H., Nature, Lond., 1977, 267, 184. Volume 2, 1973, pp. 63-84. 33, 363. Stability of Topical Steroids A. Li Wan Po, W. J. Irwin and Y. W. Yip Department of Pharmacy, University of Asto% in Birmingham, Gosta Green, Birmingham, B 4 VET Corticosteroids are used for a variety of skin conditions and in an attempt to improve their performance, more potent derivatives have been synthesised. It soon became apparent, however, that the more active molecules and in particular the fluorinated derivatives induced skin atrophy1 and were therefore not the best choice for many conditions.To overcome this difficulty, medical practitioners have resorted to the dilution of proprietary formulations with so-called “inert” bases. Such a practice has several inherent dangers, including microbial contamination of the preparations, disruption of the delivery profile of the formulation and potential catalysis of the decomposition of the steroids by the diluent.In order to investigate this last aspect, a study of the decomposition of betamethasone-17-valerate was carried out. This compound was chosen because it is one of the products most commonly diluted and because it has been shown to undergo facile isomerisation to the 21-~alerate,~ a compound shown to possess only one fifteenth of the activity of the parent i~orner.~ Initial studies were carried out using thin-layer chromat~graphy.~ The decomposition of betamethasone-17-valerate when diluted with white soft paraffin, Emulsifying Ointment BP and Plastibase 50W (Squibb Ltd.) was found to follow first-order kinetics and the observed tloyo in systems containing equal parts of Betnovate ointment (Glaxo Ltd.) and the diluents when stored at 22.5 “C are shown in Table I.White soft paraffin appears to be a suitable diluent from the point of view of stability, while Plastibase and Emulsifying Ointment BP are inadequate.Alteration of the proportion of Emulsifying Ointment BP showed that an increase in the content of the diluent increased the decomposition of the steroid, as indicated in Table 11. I t was observed that decomposition took place during the extraction if the BPC method5 was adopted. In The results clearly show that the choice of diluent is critical. Acidification of the extraction medium overcame this problem, however.334 PHARMACEUTICAL ANALYSIS Proc.Analyt. Div. Chem. SOC. TABLE I TIME TAKEN FOR 10% DECOMPOSITION OF BETAMETHASONE-17-VALERATE (tlo%) I N VARIOUS OINTMENT SYSTEMS AT 22.5 "c Observed rate constant1 Ointment system PH h-1 tlO+ Betnovate ointment + Emulsifying Ointment BP (1 + 1) 8.4 & 0.1 1.01 0.10 Betnovate ointment + Plastibase 50W (1 + 1 ) .. . . 5.7 f 0.1 4.74 x 10-1 0.22 Betnovate ointment + white soft paraffin (1 + 1) 5.6 f 0.1 6.13 x 1718.77 order to rationalise the observed effects of a change in the diluent and its proportion on the rate constant, the pH values of the systems were measured and are reported in Tables I and 11. An indirect method of pH measurement was adopted. A 30-ml volume of doubly distilled water was added to 2 g of ointment, the mixture was heated in a water-bath, the molten ointment was shaken for 10 min, cooled and the pH of the aqueous phase was measured.The results (Table 11) show that when the same diluent was used the pH was a useful monitor in that an increase in pH generally led to an increase in the observed rate constant. However, the results in Table I show that a low pH is not a guarantee of stability.Thus, although the pH of the Betnovate - Plastibase 50W system was similar to that of the Betnovate - white soft paraffin system, the stabilities of the steroid in them were vastly different, which can be explained by the presence of other catalytic species. TABLE I1 EFFECT OF AN INCREASE I N THE DILUENT FRACTION ON THE DECOMPOSITION O F BETAMETHASONE-17-VALERATE AT 22.5 "c Proportions of Betnovate ointment and Emulsifying Observed rate Ointment BP PH cons tan t/h-1 tl0 % /h 1 + 1 8.4 f 0.1 1.01 0.10 2 + 1 7.2 f 0.2 3.36 x 10-1 0.31 3 + 1 6.7 f 0.1 2.21 x 10-1 0.48 As, within a given system, a decrease in pH improved the stability of the 17-valerateJ an attempt was made to stabilise the unstable dilutions by acidification. Orthophosphoric acid (0.005~0) was added to a 3 + 1 mixture of betamethasone and Emulsifying Ointment BP.The observed rate constant at 22.5 "C was 3.85 x h-l compared with 2.21 x 10-1 h-1 although the system did not show a marked decrease in pH (6.7 to 6.3). Storage at four different temperatures showed that the observed rate constants, even in this semi-solid system, could be modelled by the Arrhenius equation : K = A exp(--E/RT) where K is the rate constant, A the frequency factor, E the activation energy, T the absolute temperature and R the gas constant.The activation energy was calculated to be 94.56 k J mol-1 and the pre-exponential factor 1.07 x 10l6 h-l. Although the thin-layer chromatographic assay used so far permitted the assay of the 17- valerate, quantitative data on the rates of formation of the 21-valerate and the alcohol were not obtainable.To overcome this, a high-performance liquid chromatographic assay was developed.6 Kinetic data obtained by storing a 0.01 yo m/V solution of betamethasone-17- valerate in propylene glycol, basified with ethanolamine (0.128%), at 60 "C showed that the decomposition of the 17-valerate followed sequential first-order A --f B +- C + D reactions and the observed rate constants were 2.446 h-l for the isomerisation reaction, 0.086 h-1 for the hydrolysis reaction and 0.050 h-l for the condensation reaction.Although the condensation product was not assayable, the availability of the hydrolysis rate constant together with the betamethasone profile permitted the calculation of the rate constant for the condensation.The proposed decomposition pathways are shown in Fig. 1. Simple partitioning between hexane and dimethyl sulphoxide permitted the analysis of the steroids in ointment systems. The ointment base is predominantly in solution in the hexaneNovember, 1979 PHARMACEUTICAL ANALYSIS 335 layer while the steroids are partitioned into the dimethyl sulphoxide layer. The partition coefficients of all three steroids were greater than 1 500 and recovery studies on commercial betamethasone-17-valerate ointment indicated a 97.20 & 0.52% (P = 0.95) value for the nominal content.H OC H 2 C H 2 N\c, C H 2 0 H COCH20H - D C Fig. 1. Decomposition of betamethasone 17-valerate with ethanolamine.The results show that the dilution of commercially available betamethasone-1 7-valerate ointment can lead to serious stability problems and that if a weaker product is required, the use of a less potent preparation is to be preferred. High-performance liquid chromatography has been shown to improve on the precision of the thin-layer chromatographic assay and enabled the profiles for the 21-valerate and the alcohol to be monitored simultaneously with that of the parent steroid.In systems studied, isomerisation was the most rapid route of decomposition, followed by hydrolysis to betamethasone. A first-order decomposition profile was observed for all three steroids in the propylene glycol - ethanolamine system. References 1. 2. 3. 4. 5. 6. Sneddon, I .B., Drugs, 1976, 11, 193. Gardi, R., Vitali., R., and Ercoli, A., Gazz. Chim. Ital., 1963, 93, 431. McKenzie, A. W., and Atkinson, R. M., Arch. Dermatol., 1964, 89, 741. Yip Y . W., and Li Wan Po, A., J . Pharm. Phormac., 1979, 31. 400. “British Pharmaceutical Codex,” The Pharmaceutical Press, London, 1973, p. 875. Li Wan Po, A., Irwin, W. J., and Yip, Y . W.. J . Chromat., 1979, 176, 399. Hygroscopic Units: a Standard Dilemma R.A. Broadbridge and J. W. Lightbown National Institute for Biological Standards and Control, Holly Hill, Hampstead, London, N W3 6RB A technique is described that allows the determination of the degree of hygroscopicity of sub- stances. Data obtained from certain biological standards has led to changes in the definition of certain international units. A microbalance head (Beckman RIIC, Type LM 600) with a radioactive a source of polonium- 210 foil (Radiochemical Centre, Amersham, Type PDV 2611, 1.7 mCi) in each chamber is housed in a convenient acrylic glove box (Mecaplex, Switzerland, Type 3011).The a source336 OBITUARY PYOC. Analyt. Div. Ckem. SOC. ionises air locally, enabling static charges present on dry materials to escape to ground. Constant humidities can be generated by placing an appropriate stirred, saturated aqueous salt solution with excess of salt in the glove box. A small fan circulates the air to speed up equilibrium conditions and prevent stratification. Very low humidity [ (1 yo relative humid- ity (r.h.)] is obtained by substituting phosphorus pentoxide powder for a salt solution. Ampouled material is opened in the box, aided by an electrically heated wire controlled extern- ally with a foot switch. The sample is transferred quickly to the balance and the output from its controller is fed, with zero suppression, to a suitable recorder, which allows for an appropriate scale expansion. For precise weighings of dry, hygroscopic materials the operation is carried out in a dried atmosphere over phosphorus pentoxide ; many very dry materials (especially when freeze-dried) will still pick up water from this atmosphere, and this is recorded, enabling an extrapolation to zero time to be made. For less exacting work, weighings can be carried out in the laboratory atmosphere and the recorded moisture uptake extrapolated similarly. As a consequence it has been recommended by the WHO1 that, where practicable, future international units will be defined on an ampoule content basis rather than a mass basis. The recently established 3rd IS Streptomycin has been defined in this manner, as has the existing International Reference Preparation for Neomycin B, together with ten other new standards. Some results obtained are shown in Table I. TABLE I PERCENTAGE MOISTURE UPTAKE (MASS/MASS) OF SOME BIOLOGICAL STANDARDS Standard* Neomycin 2 IRP . . .. Spiramycin 1 IRP . . .. Oxytetracycline 2 IS . . .. Polymyxin B 2 1st . . .. Bleomycin Pr. IRPt . . .. Nystatin 1 IS - . .. * . Diptheria antitoxin 3 BSft Chorionic gonadotrophin 2 IStt Heparin, Porcine 3 IStS . . . . 20% r.h. -7-?--- 1 rnin 5 min . . 1.1 4.3 . . 0 0 .. 0 0 .. 0.8 2.7 . . 7.1 14.5 .. 1.3 3.0 .. 0.6 3.3 . . 1.2 3.0 .. 1.9 7.2 00 11.6 0 0 7.3 15.8 4.2 6.5 4.3 9.7 65% r.h. T m s 2.3 9.1 25.5 1.0 2.3 3.3 0.1 0.3 1.1 2.1 7.5 20.3 2.5 7.2 13.0 4.1 10.8 17.1 1.1 7.9 11.2 8.4 21.6 30.3 Chemical nature Aminoglycoside Macrolide Tetracycline Peptide Anti-tumour Anti-fungal Serum Peptide/lactose Polysaccharide * IS = International Standard; (Pr) IRP = (Proposed) International Reference Preparation; BS = British Standard. t Freeze-dried. $ Labelled on an ampoule contents basis, defined on a mass basis. However, many existing and new standards will still have to be weighed and the method described here will have use for many years to come. Reference 1. Tech. Rep. Sev. WZd Hlth Org., 1979, No. 638, p. 7.

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DOI:10.1039/AD9791600320

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336 OBITUARY PYOC. Analyt. Div. Ckem. SOC. Obituary Mr. S. A. Price Stanley Albert Price was born at Harrow and ment of the National Institute for Medical educated at Harrow County School. He gradu- Research, when the Institute was at Hampstead ated in Chemistry in 1940 at Birkbeck College, under its first Director, Sir Percival Hartley. University of London. His early training in Mr Price was seconded to the Serum Department biological assay methods occurred during his of the Lister Institute during the early days of early days a t the Biological Standards Depart- the 1939-45 war.November, 1979 PUBLICATIONS RECEIVED 337 Mr.Price joined Vitamins Ltd. in 1941 and worked on the development of microbiological methods and their application to the assay of vitamins in foods and feedingstuffs and to nutritional research.During his years with Vitamins Ltd., he published several papers on topics related to the use of microorganisms for the bioassay of substances for which chemical methods were not, a t that time, sufficiently sensitive or were non-existent. After Vitamins Ltd. became a member of the Beecham Group his interests turned more to the evaluation of anti-microbial drugs and chemotherapy in general.He became Head of Parasitology a t Beecham Research Laboratories, stationed then a t Walton Oaks, and subsequently moved to Brockham Park, where he was appointed Head of Biological Screening Services for the Research Division, a position he held until his death. He was elected to the SAC Council in 1955, became Honorary Assistant Secretary of the SAC in 1957 and later became Honorary Secretary, a post in which he served for 5 years until 1968.During this period, he not only represented the Society on outside bodies, but was also Chairman of the Microbiological Panel of the ARC’S Protein Evaluation Group, amongst other panels and committees. During the whole of his working life, he showed outstanding qualities of integrity and helpfulness towards all who came in contact with him.His devotion to work and his meticulous approach won him the admiration and respect of all those fortunate to know him. He was a man of diverse interests and hobbies, many of which he enjoyed with his wife, Pat, who died 7 years ago. In more recent years he found great satisfaction in painting. During the last 3 years, Mr. Price suffered considerable ill health, which he bore and over- came with the stoicism and fortitude that were so characteristic of him. His death has deprived many of a great friend and colleague. He leaves two daughters, to whom we extend our deepest sympathies. J. GREEN A. JONES

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DOI:10.1039/AD9791600336

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November, 1979 PUBLICATIONS RECEIVED 337 Publications Received Burger’s Medicinal Chemistry. Fourth Edition. Part 11. Edited by Manfred E. Wolff. Pp. x + 1302. New York, Chichester, Brisbane and Toronto : John Wiley. 1979. Price L48.80. Food Texture and Rheology. Edited by P. Sherman. Proceedings of a Symposium held under the auspices of the Inter- national Union of Food Science and Technology at Queen Elizabeth College (University of London) December 19-22, 1977. Pp.x + 456. London, New York and San Francisco: Academic Press. 1979. Price L20; $42. Dynamische Thermische Analysen- methoden. Klaus Heide. Pp. xii + 311. Leipzig: VEB Deutscher Verlag fur Grundstoffindustrie. 1979. Price DM48. Liquid Chromatographic Analysis of Food and Beverages. Volume 1. Edited by George Charalambous.Proceedings of a Symposium on the Analysis of Foods and Beverages by HPLC, held in Honolulu, Hawaii, April 1-6, 1979. I’p. xiii + 236. New York, San Francisco and London : Academic Press. 1979. Price L10.40. Organic Reagents for Copper. Frank J . Welcher and Erwin Boschniann. Pp. xviii + 614. Huntington, New York: Robert E. Krieger Publishing Company. 1970. Price $34.50. Handbook of U.S. Colorants for Foods, Drugs, and Cosmetics. Daniel M. Marmion. Pp. x + 350. New York, Chichester, Brisbane and Toronto : John Wiley. 1979. PriceL13.25.

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338 CONFERENCES AND MEETINGS Proc. Annlyt. Div. Chem. SOC. Conferences and Meetings Plasma Emission Spectroscopy iVovewibev 2 1 , 1979, Brislol This Symposium will be held in the School of Chemistry at the IJniversity of Rristol; it is being organised by the Atomic Spectroscopy Group of the AD. The papers given will be as follows : “Plasma Emission-Yesterday, Today and Tomorrow,” by M. Sylvester; “Plasma Emission in the Chemical Industry,” by E.J . Newman; “Plasma Emission in the Water Industry,” by C. Triner; “Plasma Emission in the Analysis of Food and Biological Materials,” by M. Sargent ; and “Geochemical Applications of Plasma Emission,” by M. Thompson. In addition there will be two reviews of papers on this subject presented a t the recent International Conference on Atomic Spectroscopy : “A Review of Theoretical and Instrumental Aspects,” bv R.L. Sharp; and I l A 4 Review of the Practical Applications Biased Papcrs,” by I,. C. Ebdon. The registration fee for the Symposium, to include morning coffee, lunch and afternoon tea, will be L5.00 for students, ilO.00 for mem- bersof the Chemical Society and L15.00 for non- members. For details contact Mr.D. J . Willis, lianl; Hilger Ltd., Westwood, Rfargate, Kent. Biomedical Applications of HPLC and New Techniques Novenzbev 29, 1979, Hatfield A Symposium, organised by the Clironia1o- graphy Discussion Group, is to be held a t the Hatfield Lodge Hotel. The papers on Bio- medical Applications of HPLC will bc as follows : “Drug and Metabolite Analysis in Bio- logical Samples,” by G.Merry ; “Measurement of Vitamin D Metabolites in Serum,” by T. Clemens ; “Drug Metabolism Studies Using HPLC,” by I). R. Marten; “Determination of Ranitidine and its Metabolites in Body Fluids,” by P. Carey; and “Nucleoside and Nucleotide Analysis Using Reversed Phase HPLC,” by R. Hartwick. The papers on New Techniques will be : “Theory of Isotachophoresis and its Application to Biomcdicine,” by J .Heslop ; and “,4n Automated System for Pre-chrornato- graphic Clean-up o f Biological Samples,” by G. B. Cox. For registration forms write to the Executil-e Secretary, Chromatography Discussion Group, Trent Polytechnic, Burton Street, Nottinghani, KGl 413U. Nitrosamines in Cosmetics January 10, 1980, I,ondon A paper entitled “Iletection and Estimation of Nitrosamines in Cosmetics and Toiletries” will be presented by Dr.C. Walters (British Food Manufacturing Industry Research Association) a t a meeting of the Society of Cosmetic Chemists a t The Royal Society of Arts, 6-8 John Adam Street, London, W7C2A 6AJ, a t G.30 p.m. Contact the Society of Cosmetic Chemists, 56 Kingsway, London, WCBB 6DX. Tel. 01-242- 3800. X-ray Technique in Cosmetic Science April 10, 1980, Bath Mr.P. Hurley of Pye TJnicam will present a paper with the above title a t the Assembly Rooms, Bath. Further details from the Society of Cosmetic Chemists, 56 Kingsway, London, WC2R BDX. Tel. 01-242-3800. Analysis of Non-metals in Metals June 10-13, 1980, West Berlin This International Conference is being organised by the Gesellschaft Deutscher Chemiker in co- operation with other organisations, and will be devoted to the analysis of non-metallic elements such as H, N, 0, B, C, P, S and Se in both non- ferrous and ferrous metals. Three invited papers on the analysis of non-metals in non- ferrous metals, the analysis of non-metals in steel and activation analysis methods will be pre- sented, together with a panel discussion on reference materials.About fifty 15-minute papers are sought and abstracts should be sub- mitted by February 29th, 1980. The registra- tion fee will bc about DM250. Further details from the Conference Office, Gesellschaft Deutscher Chemiker, Herrn Ilr. J . \Vendenburg, Postfach 90 04 40, I36000 Frank- furt/Main 90, West Germany.November, 1979 CHEMICAL SOCIETY : ANALYTICAL DIVISION 339 CHEMICAL SOCIETY ANALYTICAL DIVISION JOINT PHARMACEUTICAL ANALYSIS GROUP on Short Papers in Pharmaceutical Analysis A meeting for the presentation of short papers concerned with pharma- ceutical analysis will be held at the Pharmaceutical Society of Great Britain, 1 Lambeth High Street, London, SEI 7JN, in May 1980.Authors wishing to submit papers for this meeting are asked to notify the Honorary Secretary as soon as possible, indicating the probable title of the paper and outlining the subject to be covered.Notification should be sent, not later than February 29, 1980, to: The Honorary Secretary, Joint Pharma- ceutical Analysis Group, c/o Room 407, The Pharmaceutical Society of Great Britain, I Lambeth High Street, London, SEI 7JN.Summaries of the papers presented will, if the authors wish, be published in Analytical Proceedings. ANALYTICAL DIVISION TIE The wider version of the tie bearing the SAC Coat of Arms is still available for sale to members of the CS Analytical Division. The tie, which carries a simp- lified version of the Coat of Arms woven in red, silver and gold as a single motif, is available in three different background colours-dark blue, dark green and maroon.The tie is manufactured in a Crimplene - Terylene mixture. The price of the tie is f11.70, post free. Orders, accompanied by the appropriate remittance, should be sent to The Secretary, Analytical Division, The Chemical Society, Burlington House, Piccadilly, London, W1V OBN. Please make cheques payable to The Chemical Society, and ensure that the background colour required on the tie is stated.340 CHEMICAL SOCIETY ANALYTICAL DIVISION Proc.Annlyt. Div. Chem. SOC. ANALYTICAL SCIENCES MONOGRAPHS High-Precision Titrimetry by C. Woodward and H. N. Redman This monograph was written in the hope that it will prove both helpful and interesting to practising analytical chemists. B rief contents The first section, on visual titrations, covers apparatus, preparation and assay of standard substances and preparation of standard solutions.The second section deals with instrumented titrations, including photometric and electro- metric techniques as well as miscellaneous instrumented methods. There are 83 key references to the literature on high-precision titrimetry.Paperbound 71 pp 8%’’ x 6” 0 85990 501 2 f 2.50 ($5.50) CS Members f2.00 The Chemical Analysis of Water General Principles 8 Techniques by A. L. Wilson The volume covers all stages of the complete analytical process including: deciding on the analytical information required; sampling, including place, time and frequency, as well as devices and techniques; the analysis proper and the reporting of results, their statistical treatment, and the factors involved in the choice of analytical methods (including on-line and automatic methods) for particular purposes: and data handling.Clothbound 196pp f7.50 ( $1 6.50) CS Members f5.75 8%” x 6;” 0 85990 502 0 Pyrolysis-Gas Chromatography by R. W. May, E. F. Pearson and D. Scothern Many papers have been published, particularly over the past decade, on aspects of pyrolysis- gas chromatography.A large number of different types of apparatus have been used, on a wide range of samples. This monograph attempts to present the available knowledge in a form useful to the practising analyst, helping in the choice of an appropriate method and in the avoidance of the more common pitfalls in this, perhaps deceptively, simple technique.Clothbound 11 7pp f 7.20 ( $1 5.75) CS Members f5.50 8;‘‘ x 6” 0 85186 767 7 Electrothermal Atomization for Atomic Absorption Spectrometry by C. W. Fuller Since the introduction of atomic absorption spectrometry as an analytical technique, by Walsh, in 1953, the use of alternative atomization sources to the flame has been explored. At the present time the two most successful alternatives appear to be the electrothermal atomizer and the inductively-coupled plasma.In this book an attempt has been made t o provide the author’s views on the historical development, commercial design features, theory, practical considerations, analytical parameters of the elements, and areas of application of electrothermal atomization. Clothbound 135pp f 6.75( $1 4.75) CS Members f5.00 82” x 5if” 0 85186 777 4 Dithizone by H. M. N. H. Irving The author of this monograph, who has been closely associated with the development of analytical techniques using this reagent for many years, and who has made extensive investigations into the properties of its complexes, has gathered together a body of historical and technical data that will be of interest to many practising analytical chemists. Clothbound 112pp f7.25 ( $1 6.00) CS Members f5.50 8:’‘ x 59” 0 85186 787 1 THE CHEMICAL SOCIETY, Distribution Centre, Blackhorse Road, Letchworth, Herts., SG6 ‘lHN, England.

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DOI:10.1039/AD9791600338

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年代:1979

数据来源: RSC