摘要:

Proceedinas - Iof the Analytical Division ofThe Chemical Society327327329349357357358358359360CONTENTSSummaries of Papers'Analytical Aspects of HazardousMaterials''Original Papers on PharmaceuticalAnalysis'Equipment NewsWarning of Possible Hazard in aModified Kjeldahl NitrogenDeterminationNew British StandardsAnalytical Chemistry Trust FundWater Research Centre TechnicalReportsPublications ReceivedConferences and Meetings364 Analytical Division DiaryVolume 15 No 12 Pages 327-364 December 197PADSDZ 15(12)327-364(1978)ISSN 0306-1 396PROCEEDINGSDecember 1978OF 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. 1. Coomber, O.B.E.; D. C. M. Squirrel1Secretar y Editor. ProceedingsMiss 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, Herts., SG6 1 HN.Non-members can only be supplied with Proceedings as part of a combined subscription with The Andystand Analytical Abstructs.@ The Chemical Society 1978CHEMICAL SOCIETY, ANALYTICAL DIVISIONMIDLANDS REGIONA Meeting onFLOW INJECTION TECHNIQUESatThe University of Aston in Birmingham, 24th April, 1979The speakers will include Dr. J. RhiiCka and Dr. D. Betteridge. Presentationsare invited for this meeting, and these may take the form of short papers, postersor table-top demonstrations.Summaries of proposed contributions should be sent to Dr. J. N. Miller,Department of Chemistry, Loughborough University of Technology, Lough-borough, Leicestershire, LEI 1 3TU, before February 28th, 1979

ISSN:0306-1396    

DOI:10.1039/AD97815FX047

出版商:RSC    

年代:1978

数据来源: RSC

摘要:

December, 1978 ANALYTICAL DIVISION DIARY 363Analytical Division Diary, continued Tuesday, 23rd, 4 p.m.: BelfastJanuary, continuedWednesday, 17th, 2 p.m.: LondonSpecial Techniques Group on “Analytical Useof Semi-conductors as Transducers.”Further details of this meeting may be ob-tained from Dr. R. Mounce, British Gas,London Research Station, Michael Road,London SW6 2AD.Lecture Theatre C, Old Chemistry Building,Imperial College, South Kensington,London, S.W.7.Northern Ireland Sub-Committee.“Catalytic Methods in Analytical Chemistry,”Queen’s University, Belfast.by G. Svehla.Wednesday, 24th, 7 p.m.: BathWestevn Region.“What Price Analysis,” by F. Sweeting.Chemistry Department, The University, Bath.Thursday, 18th, 12 noon: LondonJoint Pharmaceutical Analysis Group: AnnualGeneral Meeting; 12 noon.Discussion Meeting on “Analytical ProblemsAssociated with Specialised Dosage Forms” ;2 p.m.Pharmaceutical Society of Great Britain, 1Lambeth High Street, London, SE1 7JN.Wednesday, 2413, 7.15 p.m.: DarlingtonNorth East Region : Annual General Meeting,followed by a lecture.“Opium-Analysis and Anecdotes,” by C.A.Johnson.EuroPa LodgeFriday, 19th, 6.30 p.m. : Warrington Thursday, 25th, 2 p.m.: Burton-on-TrentNorth West Region : Annual General Meeting, Midlands Region.followed by the retiring Chairman’s “Analysis and the Brewing Industry,” byAddress. P. A. Martin.“Analysis-An Industrial Viewpoint,” by “The Examination of Wines and Spirits forJ . W. Ogleby. Excise Purposes,” by G.C. Hands.Training Centre, Laporte Industries Ltd ., Reception Centre, Allied Breweries (Produc-Warrington. tion) Ltd., Station Street, Burton-on-Trent .ANALYTICAL DIVISIONTIEThe wider version of the tie bearing the SAC Coat of Arms is still available forsale 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 singlemotif, is available in three different background colours-dark blue, dark greenand maroon. The tie is manufactured in a Crimplene - Terylene mixture.The price of the tie is ll.60, post free. The traditional, narrower versionof the tie is also still available (but in dark green only) at fll.10, post free.Orders, accompanied by the appropriate remittance, should be sent to TheSecretary, Analytical Division, The Chemical Society, Burlington House ,Piccadilly, London, W1V OBN.Please make cheques payable to The Chemical Society, and ensure thatthe background colour required on the tie is statedAnalytical Division DiaryJANUARYThursday and Friday, 4th and 5th: BradfordThermal Methods Group, jointly with theMacromolecular Group of the CS/ID, thePlastics and Polymer Group of the SCI andthc British Polymer Physics Group on“Thermal Methods for the Study of Poly-meric Materials.”Thursday, 4th-Introductory Address by Professor I.Goodman.“Recent Developments in Thermal AnalysisInstrumentation,’’ by P.Burroughs andM. G. Lofthouse.“Future Trends in Thermal Analyses,” byB.L. Treherne.“Problems Associated with the Application ofThermal Methods to Polymers,” by R. H.Still.“A Thermoanalytical Study of the CureCharacteristics on an Epoxy Resin System,”by J . M. Barton.“The Interpretation of TGA Data and itsMechanistic Significance,” by J. R.MacCallum.“Pyrolysis Gas - Liquid Chromatography andits Application to the Thermal Degradationof Polystyrene,” by R. S. Lehrle and R. E.Peakman.“DSC-Industrial Applications, ’’ speakerfrom Perkin-Elmer Corporation.Friday, 5th-“What Information will DSC give on GlassyPolymers?” by M. J. Richardson andN. G. Savill.“Water Binding Properties of HydrogelPolymers,” by B. J. Tighe and P. G.Pedley.“Adiabatic Calorimetry : An Investigation ofIntermolecular H-Bonding Using ModelCarbamates Structurally Related toElastometric Copolyurethanes,” by T. Fox,I.Goodman, A. F. Johnson and K. K. Lea.“Crystallisation Kinetics and MeltingStudies,” by J. N. Hay.“Heterogeneous Crystallisation of Polyethy-lene Terephthalate,” by C. Ibbotson andR. P. Sheldon.“DSC Examination of New SulphurMaterials,” by B. R. Currell, C. Stello, L.Blight and R. A. M. Scott.“Thermomechanical Methods for Researchingthe Thermal and Mechanical History ofSynthetic Fibres,” by G. D. Ogilvie andMiss L. Addyman.“The Examination of Mono-axially Orien-tated Polypropylene Films by ThermalMethods,” by J . S. Crighton.“UV Microscopy of Impurities in CrystallisingPolymers,” by P. D. Calvert and T. G.Ryan.“The Application of Thermovision to theNecking and Fracture of Polymers,” byR.N. Haward, J. N. HayandMrs J. Maher.“Electret Thermal Analysis : Instrumentationand Application to Polymers,” by R. E.Wetton.During the Meeting there will be a display ofthermoanalytical equipment.The University, Bradford.Thursday, 4th, 10.30 a.m. : SheffieldAtomic Spectroscopy Group, jointly with theBoard of Annual Reports on AnalyticalAtomic Spectroscopy and the ModernMethods of Analysis Group of the SheffieldMetallurgical and Engineering Association :Sixth Annual Reports on Analytical AtomicSpectroscopy Symposium.“Excitation and Determination of Non-metallic Elements in Atomic EmissionSpectroscopy, ’’ by J. Kijalkowski.“Determination of Mercury as Applied toGeochemical Prospecting and PollutionStudies,” by R. A. Nicholson.“Application of Electrothermal Atomisationto Sample Introduction into an ICP,” byR. D. Snook.“Atomic-absorption Analysis of GeologicalMaterials,” by J. N. Walsh.“Sampling for Spectroscopic Analysis,” byR. Smith.“Concept and Practice of Automated Emis-sion Spectrographic Analysis of GeologicalMaterials,” by D. W. Golightly.Halifax Hall, The University, Endcliffe ValeRoad, Sheffield, S10.Tuesday, 16th, 6 p.m.: LondonSouth East Region .- Annual General Meeting,“Present and Future Role of Public Analysts, ”Linnean Society, Burlington House, Picca-followed by an Ordinary Meeting.by A. J . Harrison.dilly, London, W. 1.Wednesday, 17th, 2.30 p.m. : Sheffieldand District Section of CS/RIC.Analysis,” by J . B. Headridge.North East Region, jointly with the Sheffield“A Century of Achievement in MetallurgicalCity Polytechnic, Sheffield.[continued inside back coverPrinted by Heffers Printers Ltd Cambridge Englan

ISSN:0306-1396    

DOI:10.1039/AD97815BX049

出版商:RSC    

年代:1978

数据来源: RSC

摘要:

Vol. 15 No. 12 Proceedings December 1978 of the Analytical Division of the Chemical Society Analytical Aspects of Hazardous Materials The following is a summary of one of the papers presented at the Analytical Symposium of the CS/RIC Annual Congress held on April 4th-6th, 1978, at the University of Liverpool. Summaries of five of the other papers presented at this symposium were published in the July issue of Proceedings (p.205). Analysis of Organic Peroxides N. J. Chalkley and C. Whalley Interox Chemicals Limited, Widnes, Cheshire Organic peroxides are used in the plastics industry as sources of free radicals for initiation of polymerisation. They can direct the polymerisation reaction in the best and most efficient route and, having served their particular purpose, they should readily decompose and leave no harmful residues in the product.The hazards met in manufacturing and using organic peroxides fall into three main categories, Firstly, fire hazard : organic peroxy compounds are potentially combustible materials, some of which are ignited by friction, heat or catalytic decomposition, and present a particular hazard in that they are able to supply their own oxygen to support combustion.Secondly, explosion hazard : certain pure products are explosive and thus these products are supplied commercially mixed with phlegmatisers or as solutions in inert solvents. Thirdly, toxicity hazard : certain organic peroxy compounds are covered by legislation and TLVs are listed. It is also important to know the concentration of the peroxy species in the commercial product.The analytical chemist has a key role in production control, to ensure that manufacturing processes are operating correctly and safely, and the analytical problems associated with organic peroxy compounds are numerous and varied. Analytical work can be divided into three main areas: (2) main component analysis, which product quality, for specific usage and product safety; (ii) impurity analysis, ie., the presence of impurities in the products can affect the performance of the material and may also change the hazard rating of the product; and (2;;) trace analysis of products in the manufacturing environment for the purposes of atmospheric control with relation to TLVs.In considering the main component analysis, i e ., peroxy species content, different peroxide groupings have to be considered. Some examples of organic peroxy compounds are as follows : Peroxy acids, e.g., peroxyacetic acid . . . . . . general formula R.CO.O.OH Hydroperoxides, e.g., tert-butyl hydroperoxide . . general formula RCOOH Diaroyl peroxides, e.g., dibenzoyl peroxide . . . . general formula R.CO.0O.CO.R Peroxy esters, e.g., tert-butyl peroxybenzoate .. general formula R.CO.0O.R Ketone peroxides, e.g., ethyl methyl ketone peroxide general formula HOO- [ ITO-O] -H CHJH, n (n = 1 4 ) 327328 ANALYTICAL ASPECTS OF HAZARDOUS MATERIALS Proc. Analyt. Div. Chern. SOC. R.O.CO.OO.CO.OR Peroxydicarbonates, e.g., dibutyl peroxydicarbonate Dialkyl peroxides, e.g., di-tert-butyl peroxide .. general formula R.0O.R Diacyl peroxides, e.g., dinonanoyl peroxide . . . . general formula RCO.OO.COR general formula The desirable characteristics for any method that is to be used for main component analysis are: (i) it must be simple to perform; (ii) the reagents must be readily available; (iii) it must be applicable to a wide range of products and be capable of automation. All methods that have been used for main component analysis have been based on the oxidising power of the compounds.Typical methods that have been applied in this analysis include reduction with arsenious acid, reduction with iron(I1) sulphate, reduction with tin(I1) chloride and iodimetric procedures of a wide variety. The iodimetric procedures are by far the most generally used for this determination.Although iodimetric methods have been widely applied for the determination, certain problems exist. To achieve full reaction in a reasonable time, the reaction can be accelerated by the use of catalysts, e.g., copper or iron. To avoid chain reactions with atmospheric oxygen, de-aerated solvents and an inert atmosphere, e.g., carbon dioxide or nitrogen, must be used.Further, as far as possible, heating of the reaction mixture should be avoided. Harm- ful solvents, e.g., carbon tetrachloride or chloroform, should not be used, and the preferred substitute a t present is dichloromethane. A solvent is needed in order to dissolve some formulations. A programme of work recently completed by our company and our associated company Peroxid-Chemie has succeeded in rationalising the methods for main component analysis for the organic peroxy compound product range to one standard method and two subsidiary methods.The standard method is based on an iron-catalysed procedure in glacial acetic acid media, with sodium iodide solution, in a nitrogen atmosphere. The basis for this method was first published by Silbert and Swern.l This procedure enables all of the products referred to previously, except di-tert-butyl peroxide, to be analysed.When analysing peroxy esters, it has been found necessary to use a saponification step with alcoholic potassium hydroxide, to produce the stable alkali salt of tert-butyl hydroperoxide prior to the addition of the standard reagents. The tert-butyl hydroperoxide salt formed then reacts in the usual way with the standard reagents.Di-tert-butyl peroxide is analysed by a high-temperature method developed by this company and published 12 years ago.2 Now that a standard procedure for most of the manufactured product range is available, work is in hand to produce an automated procedure, linking the partially automated chemical procedure with an electronic balance and automatic titrimeter.Impurity analysis of organic peroxy compounds is necessary for three main reasons: (i) customer requirements, e.g., chlorine contents for possible corrosion problems ; (ii) the measurement of dangerous impurities that might affect the hazardous properties of the material; and (iii) to control impurities that might be harmful in polymerisation reactions.Chlorine analysis is usually carried out by a saponification and automatic titration pro- cedure and typical values are of the order of 5 mg kg-l. Chromatography is used for the separation of impurities in organic peroxy compounds. High-performance liquid chromatography has been applied to the separation of peroxy species and phlegmatisers in ethyl methyl ketone peroxide.Gas chromatography is used for the separation of impurities in tert-butyl peroxy esters, i.e., tert-butanol, tert-butyl hydroperoxide and di-tert-butyl peroxide. Some manufacturing specifications also include examination of the product by infrared spectroscopy, whereby current material may be compared with a standard material. Finally, analysis is concerned with atmospheric pollution.To date, only three peroxy compounds have listed TLVs, viz., hydrogen peroxide, 1 p.p.m. (1.4 mg m-3) ; ethyl methyl ketone peroxide, 0.2 p.p.m. (1.5 mg m-3) ; and benzoyl peroxide, 5 mg m-3. Methods that are available for the determination of organic peroxide compounds in air are the oxidation of phenolphthalin to phenolphthalein, and titanium peroxy complex forma- tion.The latter procedure has been applied both in solution and as an impregnatedpaper technique. The disadvantage of both of these reagents is lack of specificity.December, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS 329 Work has recently been started in our laboratories with a view to producing a specific method for ethyl methyl ketone peroxide. Two gas chromatographic variations have been examined : firstly, complete thermal destruction of the peroxide, and secondly, a non- destructive procedure whereby actual peroxy species are separated. This short paper gives some indication of the complexities of organic peroxy compound analysis and the many fascinating problems that exist. The authors thank Interox Chemicals Limited for permission to publish this paper and to thank Dr. M. Koehler of Peroxid-Chemie, Munich, for his valuable advice and participation in the project. References 1. 2. Silbert, L. S., and Swern, D., Analyt. Chew., 1955, 30, 385. Adams, D. B., Analyst, 1966, 91, 397.

ISSN:0306-1396    

DOI:10.1039/AD9781500327

出版商:RSC    

年代:1978

数据来源: RSC

摘要:

December, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS 329 Original Papers on Pharmaceutical Analysis The following are summaries of seven of the papers presented at a Meeting of the Joint Pharmaceutical Analysis Group held on May l l t h , 1978, at the Pharmaceutical Society of Great Britain, London. HPLC Examination of Vitamin A and D Products I. W. Macleod and R. A. Wiggins Labornto,vy of the Gouernment Chemist, Coi~tzwall House, Stamford Street, London, SE1 9NQ Vitamin D, is manufactured by the irradiation of its pro-vitamin, 7-dehydrocholesterol. It is necessary to recrystallise the irradiated material in order to remove a series of irradiation by-products, none of which possess any antirachitic pr0perties.l It is desirable to monitor these compounds in the powder and oily concentrates of vitamin D,.Additionally, in the analysis of vitamin D, it is important to determine the potential vitamin (pre-vitamin D, plus vitamin D,) rather than just the actual vitamin ID, content because of the temperature- dependent equilibrium between vitamin D, and pre-vitamin D,.l If this determination is not carried out, divergent results will be obtained from the same sample stored under different conditions.The HPLC system described below can separate vitamin D, and its related compounds from each other; it can thus be used not only to determine the potential vitamin D, content of the concentrates, but also to monitor the level of irradiation by-products present. The column used consisted of a stainless-steel tube, 150 x 4.6 mm i d ., slurry-packed with 5 pni silica (Lichrosorb 560). The mobile phase was a 0.375% V/V solution of amyl alcohol (analytical-reagent grade) in dried hexane (Spectrosol grade ; dried by filtration through a 300 x 15 mm column of silica gel of 2.8-7.0 mm particle size). Unless the mobile phase was kept dry, by the addition of a small amount of silica gel to the solvent reservoir, the retention times decreased markedly with time and the resolution obtained suffered con- siderably. As the precise percentage of amyl alcohol required in order to achieve satisfactory separation was found to vary from column to column, it was essential to perform a test of the separating power of the system prior to use.This was carried out by injecting a mixture of trans- vitamin D,, pre-vitamin D,, vitamin D, and tachysterol, (see Fig.1). The resolution between the pre-vitamin D, and trans-vitamin D, peaks had to be at least 0.75, and for vitamin D, and tachysterol, a t least 1.0, before the system was considered suitable.2 It was also necessary to determine the response factor relating peak height for the pre- vitamin D, to the equivalent amount of vitamin D,.This determination was carried out by making a fresh 0.3% m/V solution of vitamin D, in 20y0 toluene in hexane. A 4-ml aliquot was diluted to 25 ml with 20% toluene in hexane and 5 p1 of this were injected on330 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Proc. Analyt. Div. Chem. SOC. 0 5 10 15 20 Time/m i n Fig. 1. System suit- ability test. Conditions : column 150 x 4.6 mm, 5 pm Lichrosorb 5 6 0 ; mobile phase, 0.375% V / V amyl alcohol in hexane; flow-rate, 3 ml min-1; detector, ultraviolet, 265 nm; and sensitivity 0.1 AUFS.Peak 1, pre- vitamin-D, ; 2, trans- vitamin D,; 3, vitamin D,; 4, tachysterol,. to the column in triplicate determination. A further 5-ml aliquot was refluxed for 45 min (under nitrogen, protected from light and with some crystals of butylated hydroxytoluene added), cooled to room temperature, diluted to 25 ml (with 20y0 toluene in hexane) and injected as before.The response factor (RF) was then calculated from the equation: 514 A - B C RF = where A , B and C represent average peak heights for injections of unheated vitamin D,, heated vitamin D, and pre-vitamin D, formed by heating, respectively.As this technique made use of an external standard, the reproducibility of injection was determined; the standard deviation obtained from six injections was 1.0%. Samples of oily vitamin D, concentrates were weighed out and diluted with 20% toluene in hexane so as to contain about 20 000 I.U. ml-l. The powder concentrates were saponi- fied and extracted into pentane (as in the European Pharmacopoeia procedure for vitamin A)2 before injection.The height of the pre-vitamin D, and vitamin D, peaks were measured and, by utilising the response factor, the potential vitamin D, calculated. Several samples gave peaks corresponding to various irradiation by-products. A second recorder, set to be four times as sensitive, was connected in parallel with the first recorder, thus enabling the vitamin D, peak and the impurity peaks to be measured accurately from the same injection.In the absence of reference standards for the irradiation by-products, it was not possible to calculate the precise amounts of the impurities present. However, by assuming that they all possessed approximately the same response factor as pre-vitamin D,, an estimated figure was obtained by which the different samples were compared.Preliminary investigation of simple pharmaceutical formulations indicated that both the vitamin D and A contents could be determined concurrently by use of this method. Vitamin A palmitate was saponified and extracted with ~ e n t a n e . ~ An aliquot was injected on to the column and the eluate monitored at 265nm. As anticipated, this produced a peak with a longer retention time (25 min) than vitamin D,.It gave a small additional peak a tDecember, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS 331 the same retention time as tachysterol that was assumed to be the main isomer 13-cis-retinol; this assumption was confirmed by repeating the injection after changing the detector to monitor at 325 nm.Precisely where all the isomers of vitamin A would appear in this system is not yet known, but a comparable system has been used successfully to separate them.4 A sample of vitamin A, D and C tablets was then saponified, extracted and injected: the peaks due to vitamins A and D were clearly resolved from all other peaks. A disadvantage of this HPLC system is that it is incapable of separating vitamins D, and D,.For the analysis of vitamin D, in foods and animal feeds it is necessary to separate the two nutritionally important forms ergocalciferol (Dz) and cholecalciferol (D,) . This distinction is also important where it is suspected that D, has been added to concentrates of D,. This separa- tion was achieved on a 25 cm x 4 mm column of a 5 ,xm reversed-phase packing (Spheri- sorb ODS)5 using either 95 + 5 or 90 + 10 methanol - water as the mobile phase.This system will also separate pre-vitamin D, from pre-vitamin D, and the isotachvsterols formed by isomerisation of vitamin D, and vitamin D, with antimony trich1oride.j These separations have been applied to the analysis of multi-vitamin preparations, fish oil and foods.For simple pharmaceutical preparations, e.g., vitamin A, D and C tablets and some samples of cod-liver oil, the HPLC separation of vitamin D, and D, can be performed directly on extracts of samples prepared either by solvent extraction or saponification (see Fig. 2). In these instances the time of analysis for vitamin D is approximately 1-1i h. For the more complex multi-vitamin preparations and foods some preliminary purification is necessary before extracts can be applied to the HPLC column.60 50 40 30 20 10 0 Tirne/min Fig. 2. Determination of vitamin D, in cod liver oil. Conditions: column 25 cm x 4 mm, 5 pm Spherisorb SBODS; mobile phase, 90% methanol - 10% water; detector, ultraviolet, 254 nm ; sensitivity, 0.01 AUFS; and sample size, 4 pl injection from a 300 p1 concen- trated extract of a 10-g sample of cod-liver oil.Peak A, vitamin D, (internal standard) ; B, vitamin D,. The vitamin D is initially extracted from food or preparation by saponification, followed by the extraction into ether of unsaponifiable material. A solution in chloroform of the unsaponifiable material is then made to react with antimony trichloride to isomerise the vitamins D to the corresponding isotachysterols.(Any pre-vitamins D present will also be converted into the isotachysterols.) The isotachysterols are chromatographically separated on a dry column (40 x 1 cm) of neutral alumina that has been de-activated with 10% of water. The purified isotachysterols are then separated by HPLC. The microparticulate reverse- phase packing used in these determinations will resolve vitamin D, from vitamin D, and iso- tachysterol-2 from isotachysterol-3.As it is rare to encounter samples in which both forms of vitamin D are present, it is usually practical to take one form of vitamin D as a mutual internal standard for the other. As the two forms of vitamin D are chemically similar, this internal standard can be added at the beginning of the analysis.For example, in the procedure332 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS R o c . Analyt. Div. Chem. SOC. described for the analysis of foods, the internal standard is added before the saponification. The contents of vitamin D and isotachysterols are determined by measurement of absorbance peak heights at 254 and 280 nm, respectively.It is our experience that it is necessary to take an amount of sample for analysis that contains at least 3 4 p g of vitamin D. The retention characteristics are the reverse of those of the silica columns as retinol elutes before vitamin D. This HPLC separation has been used for the quantitative determination of retinol in fish oils, pharmaceutical preparations and foods. The extracts were prepared by saponification and ether extraction and retinyl acetate was used as the internal standard.Columns of 5 pm Spherisorb ODS will also separate all-trans-retinol from its esters. References 1. 2. 3. 4. 5 . Keverling Buisman, J . A., Hanewald, K. H., Mulder, F. J., Roborgh, J. R., and Keuning, K. J., J . Personal communication from Philips-Duphar, relating to EPC studies.European Pharmacopoeia, Volume 111, 1975, p. 367. Nedelkovitch, G., Personal communication relating to EPC studies. Wiggins, R. A., Chemy Ind., 1977, 841. Pharm. Sci., 1968, 57, 1326. Determination of Impurities in Phenindione P. A. Haywood, G. Munro and Mrs. S. M. Vaughan Analytical Research Departmewt, Glaxo-Allenburys Research (Ware) Ltd., Priory Street, Ware, Hertfordshire Phenindione (I), a synthetic anticoagulent, has been reported as being readily converted by autoxidation into a dehydrodimer (11), which, on heating, may yield a rearranged dimer (111) .l,z Further, Zalukaev and Belyaeu3,4 have suggested that lactone formation may occur on oxidation to give the hydroxyisocoumarin (IV) and Bungaard5 has claimed that benzalphthalide (V), another oxidation product,6 may be responsible for the allergic hyper- sensitivity reactions occasionally associated with phenindione therapy.Because phenindione (I) is clearly susceptible to ~xidationl-~,~ and because no satisfactory procedures for the determination of impurities in this drug (I) have been reported, we have investigated thin- layer and high-performance liquid chromatographic methods. Preparation of Impurities The dehydrodimer (11) and rearranged dimer (111) were synthesised by the method of Beringer et aL2 Attempts to synthesise 3-phenyl-4-hydroxyisocoumarin, as described by Zalukaev and B e l y a e ~ , ~ * ~ failed but led to the isolation and identification of the furan-l-one (VI).2-Hydroxy-2- phenylindan-l,3-dione (VII) was prepared by treating I in aqueous alcoholic solution with magnesium oxide.Thin-layer Chromatography Benzalphthalide (V) was obtained from a commercial source. A system was established to separate the potential impurities that had been synthesised. Table I shows the R, values for these impurities and phenindione. TABLE I THE THIN-LAYER CHROMATOGRAPHY OF PHENINDIONE AND ITS IMPURITIES Chromatographic conditions : chromatoplates, silica gel 60F254 (0.25 mm thick) ; mobile phase, toluene - ethyl acetate (100 + 5 ) ; detection, narrow and broad range ultraviolet lamps.Compound RF value Benzalphthalide (V) 0.45 3-Phenyl- 1,S-dihydrobenzo (c) furan- l-one (VI) 0.38 Dehydrodimer (11) 0.35 Phenindione (I) 0.30 2-Hydroxy-2-phenylindan- l13-dione (VII) 0.05 Rearranged dimer (111) 0.09 Both dehydrodimer (11) and benzalphthalide (V) were detected in the first batches of phenindione examined, albeit at low levels, but no rearranged dimer (111) nor furan-l-oneDecember, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS 333 0 0 / V 0 o \ I “12 \ 0 I V @p \ 0 V I I VI I Phenindione; 2-phenylindan-l,3-dione I I Dehydrodirner; 2,2’-diphenyl-2,2’-biindan-lI 1’,3,3’-tetrone I I I I V 3-Phenyl-4-hydroxyisocournari!i V Benzalphthalide; 3-benzylidenephthalide VI 3-Phenyl-1, 3-dihydrobenzo ( c ) furan-I-one V I I 2-Hydroxy-2-phenylindan-1, 3-dione Rearranged dirner; 2-phenyl-2-[O-(indan-lr 3-dion-2-yl) phenyl] 1, 3-indandione (VI) was observed.Subsequent monitoring of both freshly synthesised phenindione and phenindione stored at elevated temperatures and high humidities has failed to detect either of these compounds.However, a spot corresponding in R, value to 2-hydroxyphenindione (VII) was seen in all the drug samples examined. Concurrent with our work Engel and Koekkoek7 reported the presence of 3-phenyl-4-hydroxyisocoumarin (IV) caused by the decomposition of phenindione on the chromatoplate during thin-layer chromatography.Unfortunately, in Engel and Koekkoek’s system VII was found to have an R, value identical with that reported for IV.7 Preparative thin-layer chromatography failed to produce samples of the impurity that were pure enough for identification purposes, probably because of decomposition on the plate.7 Nevertheless, quantitative determination of the amounts of dehydrodimer (11), benzalphthalide (V) and the low R, impurity was attempted by using a Vitatron flying-spot densitometer.A linear relationship between the amounts of de- hydrodimer and benzalphthalide standard spots and the instrument response was established for the range 0.2-2.5 pg of each compound, using the fluorescence mode of measurement. Good reproducibility of analysis for these impurities in batches of phenindione was subse- quently achieved.Unfortunately, in those batches of drug where the unidentified low R, impurity was detected, non-reproducible results were obtained when determinations were334 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Proc. Analyt. Div. Chem. SOC. made by comparison with standard phenindione (I) spots. In this instance fluorescence quenching had to be used because neither phenindione (I) nor the unidentified spot possessed sufficient native fluorescence to allow analysis.Further investigation of the non-repro- ducible results revealed that the amount of the impurity detected increased with the time that phenindione was allowed to remain in contact with the chromatoplate prior to its development, suggesting that decomposition was occurring on the plate, Reverse-phase high-performance liquid chromatography (HPLC) offered one possible solution to this problem because with the effective blocking of the silica’s polar silanol groups a likely source of interaction between drug and chromatoplate would be eliminated.High-performance Liquid Chromatography By using a reverse-phase system, chromatograms such as that shown in Fig.I were obtained following the injection of test mixtures of phenindione (I), 2-hydroxyphenindione (VII) and those impurities detected by thin-layer chromatography (I1 and V). Serial injections of phenindione solutions were then made on to the HPLC column and the fractions con- taining the unidentified impurity were collected.Proton magnetic resonance and infrared spectroscopic examination of the material contained in the bulked fractions confirmed that the impurity was 2-hydroxyphenindione (VII) . Subsequently, using biphenyl as an internal standard (see Fig. l), accurate response factors were calculated for phenindione (I) and the impurities detected, 11, V and VII, at a compromise wavelength (254 nm) which gives adequate sensitivity (1-2 ng) for each compound.The 95% confidence limits for a single injection of a single sample were calculated from ten replicate analyses and found to be &lyo for phenindione and -+5-10% for the impurities. We feel that these values are satisfactory because the impurities were present at a level of only o.1-o.470 m/m. To ascertain the accuracy of the method a solution of phenindione containing biphenyl was prepared and analysed before consecutive additions of a solution containing 2-hydroxy- phenindione (VII), benzalphthalide (V) and dehydrodimer (11) were made.The phenindione solution was re-analysed after each addition and it was found that the peak area of each of the three impurities relative to that of biphenyl increased linearly with the amount of the 5 L U - 3 6 4 2 Tirne/min Fig.1. HPLC separation of phenindione from those im- purities detected by thin-layer chromatography. Column : 20 x 0.5 cm i d . stainless steel packed with 10-pm Spheri- sorb ODs. Eluent: ethanol - water (2 + l ) , flow-rate 1.0 ml min-1. Detection: UV a t 254 nm. Peaks: 1, phenindione ; 2, 2-hydroxyphenindione : 3, dehydrodimer ; 4, benzalphthalide; 5, biphenyl (internal standard).December, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS 335 appropriate impurity added.Further, the concentrations of the three impurities (11, V and VII) obtained by this standard addition technique were identical with the initial analysis, suggesting that no on-column decomposition occurs (cj., thin-layer chromatography), that the solutions for analysis are stable and that the accuracy of the method is good.In conclusion, and like the thin-layer chromatographic system described (Table I), our HPLC method, while separating 11, V and VII, is also capable of separating I11 and VI, but neither of these has been detected. We thank Dr. L. R. Rowe for his advice and encouragement in the performance of the work and the preparation of this paper.References 1. 2. 3. 4. 5. 6. 7. Rigaudy, J . , and Aubrum, P., C.R. Hebd. Se'anc. Acad. Sci., Paris, 1962, 254, 2,372 374. Beringer, F. M., Galton, S. A., and Huang, S . J., Tetrahedron, 1963, 19, 809. Zalukaev, L. P., and Belyaeu, V. N., Dokl. Akad. Nauk. SSSR, 1967, 175, 1285. Zalukaev, L. P., and Belyaeu, V.N., Zh. Org. Khim., 1969, 5, 727. Bungaard, H., Acta Pharm. Suec., 1975, 12, 333. Rigaudy, J . , and Derible, P., Bull. SOC. Chim. Fr., 1965, 3047. Engel, D. J . C., and Koekkoek, P. H., J. Chromat., 1975, 108, 117. Application of lsoelectric Focusing in the Identification of Allergen Materials J. Harfield, J. C. Deavin and J. Terry E. Merck Ltd., Four Marks, Alton, Hampshire The current procedures for identifying allergen materials rely on the visual - microscopic identification of the raw material and a knowledge of its source.These procedures can only be applied at the raw material stage and are often insufficiently sensitive to distinguish between related allergens. Investigations began with gel electrophoresis ; however, the pattern produced was not sufficiently detailed for identification purposes.From gel electrophoresis the technique known as isoelectric focusing (IEF) was introduced in the late 1960s for the identification of allergen materials. History of Isoelectric Focusing Isoelectric focusing dates back to an experiment of Ikeda and Suzukil in 1912, when a coarse separation of amino acids from plant protein hydrolysates was achieved in a three- chambered electrolysis cell.This work was extended to involve a multi-chamber electro- lysis cell in 1929 by Williams and Waterman.2 These pioneer experiments suffered from the lack of suitable ampholytes for developing smooth pH gradients that were also sufficiently stable to allow true equilibrium focusing. The rapid practical application of IEF followed the work of Svensson, who laid the theoretical foundations for present-day systems.In a series of articles, Svensson3s4 and Rilbe,5 from a theoretical basis, predicted the properties that ampholytes would need to possess in order to realise true equilibrium focusing. Unfortunately, their ampholytes were useful only over a very narrow range of pH. In 1969, Vesterberg' synthesised carrier ampholytes, which formed smooth pH gradients between pH 3.5 and 10.These ampholytes can now be readily synthesised following developments by Vino- gradov et aZ.,s Pogacar and Jareckis and Righetti et ~ ~ 1 . 1 ~ However, these ampholytes, when prepared on a laboratory scale, suffer from large variations between batches and poor repro- ducibility of result s.It was not until the commercially produced ampholytes became available that repro- ducible results could be achieved. These were introduced in the form of polyacrylamide gel plates during the latter half of 1976, and since then it has been possible to obtain repro- In 1966, Svensson and Vesterberg6 confirmed Svensson's predictions.336 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Proc.Analyt. Div. Chem. SOC. ducible results on suitably prepared samples and to distinguish between closely related allergens. Basic Principle Electrophoretic mobility has long been used as a basis for separating and characterising proteins. Isoelectric focusing is essentially an equilibrium electrophoretic method for segregating amphoteric macromolecules according to their isoelectric points in a stable pH gradient.Unlike ordinary electrophoresis at a single pH, the protein is concentrated into a very narrow band while the electric current is applied and IEF has now been refined to the point where components, the isoelectric points of which differ by as little as 0.01 pH unit, can be displayed. The separation of these components is of importance in the characterisation of allergenic materials.Allergen extracts may contain upwards of 20 different molecular species. Procedure Equipment and Methods different techniques have been developed which suit our particular working arrangements. Satisfactory results can be obtained by using LKB equipment and methods. Slightly Sample preparation This is very important as IEF is only possible at the correct sample concentration and with an electrolyte concentration below 0.01 M.It is important to concentrate the sample correctly and ensure that the electrolyte concentration is below 0.01 M. The electrolyte levels in the sample are reduced by a dialysis procedure. Concentration of the sample can be achieved either by lyophilisation and re-dissolution in a known volume of de-ionised water, or by dialysis against polyethylene glycol.Polyacrylamide gel $reearation It is possible to apply 24 samples on a full plate by correct placement of the sample application pieces, but the PAG plate can also be cut into halves or thirds with sharp scissors when it can carry fewer samples. The PAG plate is placed on the template and the cooling plate with insulating fluid (kerosene or light paraffin oil) in between.Place the ampholine polyacrylamide gel (PAG) plate on the cooling plate. Application of electrode strips PAG plate and trimmed to the correct length. cathode electrode solution and similarly applied and trimmed. One electrode strip is saturated with anode electrode solution, placed carefully on the The other electrode strip is saturated with Sample application The amount used is determined by the sample concentration (the usual amount is 2-3 000 PNU in 50 p1 where 10 000 PNU = 0.1 mg of protein nitrogen).The normal procedure is to soak small pieces of filter-paper with different samples and apply them directly to the PAG plate 5 mm apart. The position of the sample is normally at the cathode end.Focusing conditions 35 W ; maximum amperage 45 mA ; and minimum time 90 min. The conditions are temperature 4 "C; maximum voltage 1500 V; maximum wattage Fixing, staining, de-staining and preserving Standard LKB techniques can be used. Isoelectric focusing applied to the quality control of nllergen extracts In the absence of international standards, the guiding principle is that all protein bandsDecember, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS 337 are significant in the characterisation of the product and the absence of a band may be considered detrimental to efficacy.The isoelectric pattern is compared with the in-house standard, and where any differences are observed the test material is rejected. During manufacture, IEF can be used to control intermediate extracts as well as final material in order to ensure that processing has not exerted an adverse effect. Incoming allergen materials are examined physically and by isoelectric focusing.Results The major difficulty with this technique is the complex pattern of protein staining For example, by using densitometry it is possible to observe 28 protein bands A number of tests were carried out to establish identity by IEF observed.from 6 grass mix extract. under different circumstances. Identity within groups Fig. 1 illustrates IEF patterns of different tree extracts (1-lo), 6 tree mix, 6 tree mix, alder, alder half dilution, alder third dilution, hazel, willow, willow half dilution, birch, birch half dilution. NOTE- pattern 8 shows a loss of a prominent band towards the cathode on dilution.Serial dilutions of alder and willow were run in order to attain optimum concentrations; willow Fig. 2 illustrates a range of moulds (1-lo), Helnzinthspore, Mucor sp., Rhixopus nigrass, Pullularia pullulans, Neurospora sitophilia, Serpula lacrimans, Helminths$orium, Rlaixopus nigrass, Neurospora sitophilia, Serpula lacrimans. Fig.1. IEF patterns of tree extracts. Fig. 2. IEF pattern of moulds. Identity between groups Fig. 3 shows the significantly different patterns for tree, moulds, feathers, epithelia and flowers (1-7), birch, Artemisia, Penicillium, budgerigar feathers, daisy, cat, cat. Fig. 4 illustrates a range of weeds and two grasses (1-8), 5 weed mix, dandelion, Artemisia, nettle, plantain, pellitory, 5 weed mix, Artemisia.Fig. 5 shows significantly different bands for moulds, tree, weeds, feathers and flowers (1-10) , Chaetomium globosuunz, aster, Botrytis cinerea, Curvularia, 5 weed mix, Fusarium, feather mix, Candida albicans, dahlia, chrysanthemum. Fig. 6 shows significantly different bands for stinging insects, house dust mite, grass dust (1-6), hornet, wasp, house dust mite, budgerigar, cocksfoot, house dust.Fig. 7 (1-lo), Aspergillus, maize, nettle, barley pollen, nettle, wheat, plane tree, plane tree, house dust, cocksfoot. (Nettle needs to be more concentrated.)338 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Proc. Analyt. Div. Chem. SOC. Fig. 3. IEF patterns of different species. Fig. 4. IEF patterns of weeds and grasses. Fig. 5. IEF patterns of different Fig.6. IEF patterns of species. different species. Detection of material stored under adverse conditions Fig. 8 illustrates the effect of degradation of birch (1-3), birch untreated, birch treated, birch untreated. The reproducibility of the procedure is such that extracts focused on different occasions show, in each profile, peaks of allergenic activity occurring at the same position in the gel.Further work will indicate whether reproducibility can be achieved between different extracts obtained from allergenic materials collected during different seasons. Results to date suggest that it is possible to differentiate between the materials tested provided that comparable concentration levels are adopted. Conclusion As a sensitive and specific procedure for the rapid differentiation of various allergen materials, the method forms a basis for determining allergenic activity and provides a quality assurance method for in-process control of allergenic substances both in the raw state in- process and as finished bulk extracts.In addition to the current programme involving examination of a wide variety of allergenic extracts, it is expected to quantify the procedure and to use IEF in conjunction with the RAST (Radio Allergo Sorbent Test) technique in order to correlate therapeutic activity with composition.December, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS 339 1.2. 3. 4. 5. 6. 7. 8. 9. 10. Fig. 7. IEF patterns of different species. Fig. 8. IEF pat- terns showing de- gradation of birch.References Ikeda, K., and Suzuki, S., U.S. Pat. 1015-891, 1912. Williams, R. R., and Waterman, R. E., Proc. SOC. Exp. Biol. Med., 1929, 27, 56. Svensson, H., Acta Chem. Scand., 1961, 15, 325. Svensson, H., Acta Chem. Scand., 1962, 16, 456. Rilbe, H., Ann. N.Y. Acad. Sci., 1973, 209, 11. Vesterberg, O., and Svensson, H., Acta Chem. Scand., 1966, 20, 820. Vesterberg, O., Acta Chem.Scand., 1969, 23, 2653. Vinogradov, S. N., Lowenkron, S., Andonian, H. R., Bagshaw, J., Felgenmauer, K. and Pak, S. J., Biochem. Biophys. Res. Commun., 1973, 54, 501. Pogacar, P., and Jarecki, R., in Allen, R. C., and Maurer, H., Editors, “Electrophoresis and Isoelectric Focusing in Polyacrylamide Gels,” W. de Gruyter, Berlin, 1974, pp. 153-158. Righetti, P. G., Sep. P w i f .Meth., 1975, 4, 23. Spectrophotometric Determination of Tromethamine 1. M. Beaumont and A. C. Mehta Pharmacy Department, Leeds General Infirmary, Leeds, LSl 3EX Tromethamine (Tham-E) is a diuretic used in the treatment of metabolic, respiratory, diabetic and postoperative acidosis. It is a primary amine, with the following structure: NH2 I HOCH,-C--CH2OH I I CH20H It has been proposed that a cardioplegia electrolyte additive solution should be prepared in the hospital pharmacy sterile production department. This solution contains tro- methamine at a concentration of 13.5 mg ml-l, together with the inorganic salts potassium chloride, sodium chloride and magnesium sulphate.The concentrated solution is packed in ampoules, which are intended to be added to an intravenous infusion fluid immediately before administration to the patient.For the routine quality control of tromethamine, a340 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Proc. Analyt. Div. C h e w SOC. rapid, sensitive, simple and accurate method is required. The present work was undertaken with this end in view. Many assay methods for tromethamine have been reported.1-9 A colorimetric method' involving diazotisation and coupling is rather long and a gas-chromatographic procedures involving a derivatisation reaction is complex and probably more suited to body-fluid analysis.The colorimetric method of Zaar and Gronwall2 requires the use of a corrosive reagent, boiling sulphuric acid, and the titration method of Chapman et requires strict control of experimental conditions and is specially designed for urine analysis.A colori- metric method5 involving the oxidation of tromethamine by potassium dichromate did not yield satisfactory results. We also tried certain titration methods that are suggested for primary amines but they did not give definite end-points. We propose here a method that is a modification of a general spectrofluorimetric procedure for primary amines involving their reaction with o-phthalaldehyde in alkaline medium a t room temperature in the presence of the reducing agent 2-mercaptoethan01.l~ This reaction was successfully applied to tromethamine, but the absorbance of the reaction product rather than its fluorescence was measured by using an ultraviolet spectrophotometer.Materials and Methods Reagents Analytical- or laboratory-reagent grade chemicals purchased from BDH Chemicals Ltd.were used. The stock solutions were prepared as follows : o-phthalaldehyde, 10 mg ml-I in ethanol; 2-mercaptoethanol, 5 mg ml-l in ethanol; disodium tetraborate, 0.05 M, pH 9.5; and standard aqueous solutions of tromethamine as appropriate. All of these solutions were found to be stable when stored in the dark at room temperature.The reagent solution used in the assay was prepared freshly by adding 1 ml of o-phthalaldehyde solution to 1 ml of 2-mercaptoethanol solution and making up to 100 ml with disodium tetraborate solution. The reagent was found to deteriorate rapidly on storage, and so it is advisable to use freshly prepared solutions for each test.Apparatus A Varian Model 635 scanning spectrophotometer coupled to an Oxford Series 3000 recorder was used in initial studies to determine the ultraviolet absorption characteristics of the reaction product. Thereafter, the fixed wavelength measurements were taken using a Pye Unicam SP500 spectrophotometer. Procedure The solution under test is diluted to bring the tromethamine concentration to about 100 pg ml-l (for our intravenous additive solution, a dilution of 1 to 100 is used to dilute the tromethamine concentration to 135 pg ml-l), then 10 ml of the reagent is added to 1 ml of this diluted solution and the mixture is agitated, by using a vortex mixer, for 5 s.The reaction is allowed to proceed at room temperature for 30 min, after which the absorb- ance a t 338 nm of a 1-cm layer is measured, using a blank solution (substituting 1 ml of water for a sample) in the reference cell.The absorbance produced by the unknown con- centration of tromethamine is compared with that of a standard solution and the concentra- tion of the unknown is calculated from the simple formula Concentration = E338 (sample) x concentration of standard (in pg ml-l) (standard) Results and Discussion The absorption spectrum of the reaction product was found to have three peaks, with maxima a t 338, 260 and 237nm.However, on testing various concentrations of tro- methamine the sizes of the 260 and 237 nm peaks were found to be steady, so that only the maximum at 338 nm was used for further measurements as the peak at this wavelength remained proportional to the tromethamine concentration.December, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS 341 Time of Reaction Using the chart recorder, graphs were produced of absorbance at 338nm veysus time These tests were repeated using aged reagent, and the results are shown in (Fig.1). Table I. TABLE I CHANGE OF TROMETHAMINE ABSORBANCE WITH TIME Concentration, 150 pg ml-l; wavelength, 338 nm.Age of reagent/h E338 (max.) Time to reach plateau Fresh 0.435 l h 1 0.420 l h 4 0.230 30 min 24 0.000 - Using fresh reagent the time to reach the plateau, as shown in Table I, is 1 h ; however, as can be seen from Fig. 1, results read after 30 min are on the slightly sloping part of the graph, and so errors introduced by inaccurate timing of the results in this region are very small indeed (a timing error of 2 min causes less than 1.5% error).Thus, readings can be taken between 30 min and 2 h without introducing a significant error. Table I shows that 1 h old reagent still gave satisfactory results, but reagent prepared 4 h previously had deteriorated significantly and 24 h old reagent did not react to produce a compound with an absorption maximum at 338 nm.0.5 1 0.4 a, 0.3 fl, 8 2 0.2 0.1 0 15 30 45 60 90 120 T ime/m in Fig. 1. Absorbance of reaction product a t 338 nm v e m u time (tromethamine concentration, 150 pg ml-l). Linear Concentration Range concentration range. Serial dilutions of a standard tromethamine solution were prepared to find the linear The results are given in Table 11.TABLE I1 CHANGE OF TROMETHAMINE ABSORBANCE WITH CONCENTRATION Wavelength 338 nm. Concentration/pg ml-l E338 227.2 0.605 170.4 0.502 113.6 0.345 56.8 0.175 28.4 0.085 14.2 0.040 From Table I1 it can be seen that above 100 pg ml-1 the precision of the method decreases342 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Proc. Analyt. Div. Chem. Soc. as the measured extinction is non-linear.The best results are obtained in the 10-100 pg ml-l range, where the experimental error is less than 2%. The reproducibility of the method was checked by repeating the test five times with a known concentration of tromethamine. The standard deviation was found to be 0.005 and the coefficient of variation 1.25%, showing that the reproducibility of the results is very good. Effect of Inorganic Ions The cardioplegia electrolyte additive solution contains potassium chloride 80 mg ml-l, sodium chloride 84.5 mg ml-1, magnesium sulphate 20 mg ml-l, glacial acetic acid for the adjustment of pH and tromethamine at a concentration of 13.5 mg ml-l.For our test this solution is diluted 1 in 100, giving a final concentration of the inorganic salts in the test solution of potassium chloride 800 pg m1-1, sodium chloride 845 pg ml-l and magnesium sulphate 200 pg ml-1.At this concentration no effect on the absorbance of tromethamine at 338nm can be detected. It can be concluded that this method is satisfactory for the analysis of the solution as prepared by the hospital pharmacy sterile production department. Analysis of Tromethamine Solutions Three samples of electrolyte additive solution were prepared, each containing different known amounts of tromethamine.These solutions were assayed to find the error introduced during the test. The results (Table 111) show that the error is less than 2%. TABLE I11 ANALYSIS OF TROMETHAMINE SOLUTIONS Tromethamine presentlmg ml-l Tromethamine found/mg ml-' Error, % 13.70 13.64 0.44 9.630 9.640 0.11 6.420 6.495 1.2 Structure of Reaction Product However, l-alkylthio-2- alkyl-substituted isoindole may be produced, as has been suggested by Simons and Johnsonll in connection with their structural studies of the products of the reaction between amines and a mixture of o-phthalaldehyde and 2-mercaptoethanol.No attempts have been made to identify the reaction product.Conclusion A method has been developed that will determine tromethamine quantitatively in aqueous solutions in the 10-100 pg ml-1 range. The method is rapid, sensitive, simple and accurate to within 2%. It is not affected by the presence of inorganic ions present at the concentrations usually encountered in an intravenous preparation , and can be used for the routine determination of tromethamine in cardioplegia electrolyte additive solutions.The present work deserves further study, particularly to determine whether the reaction product is fluorescent. Most probably it will prove to be so, and the fluorescence could be used to develop a more sensitive assay procedure for tromethamine. Such an assay might be useful in the analysis of this compound in biological fluids; however, the proposed spectro- photometric assay is adequate for the routine assay of tromethamine in intravenous fluids.Expensive or unusual instrumentation is not required. References 1. 2. 3. 4. 5. 6. 7. Clark, L. C., Ann. N.Y. Acad. Sci., 1961, 92, 687. Zaar, B., and Gronwall, A., Scand. J . Clin. Lab. Invest., 1961, 13, 588. Rosen, H., Ann.N.Y. Acad. Sci., 1963, 92, 414. Linn, S., and Roberts, M., Ann. N.Y. Acad. Sci., 1963, 92, 419. Straws, J., Bernath, K., and Kaplan, S. A., Proc. Soc. Exp. Biol. Med., 1963, 113, 58. Chapman, S. R., Smith, L. M., and Simmons, D. H., J . Lab. Clin. Med., 1965, 66, 698. Kanarek, A., and Tal, M., Analyt. Biocheun., 1974, 57, 78.December, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS 8.9. 10. 11. Fischer, A., 2. Analyt. Chem., 1975, 276, 79. Hulshoff, A., and Kostenbauder, H. B., J . Chromat., 1978, 145, 155. Roth, M., Analyt. Chem., 1971, 43, 880. Simons, S. S., and Johnson, D. F., J . Am. Chem. Soc., 1976, 98, 7098, 343 Low-temperature Infrared Spectra of Pharmaceuticals W. S. Brickell Physical Chemistry Department, Glaxo Reseaxch Ltd. , Greenford, Middlesex, UB6 OHE Techniques for recording infrared spectra a t low temperatures have been available for 40 years.Cooling a Nujol mull of a crystalline sample to the temperature of liquid nitrogen leads to a reduction in molecular randomness, and hence to an enhancement of resolution.lS2 This enhancement includes a narrowing and an increase in the intensity of the bands, plus the resolution of shoulders and the appearance of previously hidden features.As high- energy grating spectrophotometers are now common, liquid nitrogen is readily available and variable temperature units are also commercially available, the recording of infrared spectra a t sub-ambient temperatures is a realistic proposition for many analytical spectro- scopy laboratories. The comparison of closely similar spectra is simplified when high resolution spectra are used. Many pharmaceuticals (e.g., steroids and cephalosporins) exist as polymorphs, which are distinguishable by solid-state infrared spectroscopy.Polymorphism is now a subject of major importance to the pharmaceutical industry because changes in crystal form are often associated with differences in physical properties, and hence in bioavailability.By cooling samples to the temperature of liquid nitrogen, it becomes easier either to distinguish between crystal forms, which at room temperature exhibit only small differences in their solid-state infrared spectra, or to identify absorption bands specific to one form in a mixture of crystal forms. The enhancement of resolution that occurs on cooling griseofulvin is shown in Fig.1. Fig. 1. Infrared spectra of griseofulvin Nujol mull at R” and 77 K. References 1. 2. Sheppard, N., in Sell, G., Editor, “Molecular Spectroscopy,” Institute of Petroleum, London, 1955, Katon, J. E., and Phillips, D. B., AppZ. Spectrosc. Rev., 1974, 7, 1. p. 36.344 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Proc. Analyt. Div.Chem. SOC. Detection of an Epimer in a Novel Aminoglycoside R. D. Gifford Analytical Cloemistry, Pfizer Central Research, Pfizer Limited, Sandwich, Kent This summary describes the detection and quantification of an epimeric impurity in a pharmaceutical development compound by j oirit application of spectroscopy and chromato- graphy. Interpretation of 13C nuclear magnetic resonance spectra (CMR) established the nature of the impurity, and ion-exchange high-performance liquid chromatography (HPLC) provided a routine assay.HO 11 p 2 i, I; UK-18, 892; I I; UK-34, 688; Z = (S)-CH2CH(OH)CH2CHZNH2 Z = (R)-CH;!CH(OH)CH;,CH2NH2 I I I; Kanamycin A; Iv; (S)-Glycerylkanamycin A; v; (R)-Glycerylkanamycin A; Z = H Z = (S)-CH,CH(OH)CH,OH Z = (R)-CH2CH(OH)CH20H UK-18892 (I) is a broad-spectrum antibiotic, the synthesis and antibacterial properties of which were reported last year.l The amino group at the 1-position of the 2-deoxy- streptamine moiety is alkylated with the 8-amino-P-hydroxybutyl group, having the S configuration at CP.During the early stages of development of UK-18892, CMR played an important part in structural studies. The spectra discussed in this summary were obtained on a Varian XL-100/15 spectrometer operating in the Fourier transform mode with full noise-modulated proton decoupling.The sample was dissolved in deuterium oxide at a pD of 3 and saturated with oxygen, and tetramethylsilane was used as an external standard. The 22 carbon nuclei in UK-18892 give rise to 22 single resonances, which have been fully assigned by comparison with model compounds, consideration of deuteronation shifts and other tech- niques.During work on various synthetic routes to UK-18892 three additional peaks were observed in the CMR spectra of some samples, suggesting that an impurity was present. The impurity peaks were close to the resonances of CP, C1 and Ca, three nuclei in the vicinity of the asymmetric centre CP.The epimer UK-34688 (11) was suspected, as a change in configuration at CP is likely to cause shielding differences at adjacent carbon nuclei similar to those observed. Synthesis of UK-34688 and comparison of its spectrum with that of UK-18892 confirmed the hypothesis. Chemical shift differences, A8 [A8 = 8 (UK-18892)- 8 (UK-34688) for corresponding carbon nuclei in the two isomers], of approximately 1 p.p.m.were observed for CP, C1 and Ca (Table I). Further, spectra of synthetic mixtures of the epimers were comparable with those of the problem batches of UK-18892; the CP, C1 and Ca nuclei each gave a pair of resonances. In the spectra of 50:50 mixtures small differences in chemical shift were also observed for the C2 and C6 nuclei (Table I).The analogous 1-N-glyceryl kanamycin A epimers (IV and V) showed similar behaviour (Table I), providing useful confirmatory data.December, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS TABLE I l3C CHEMICAL SHIFT DIFFERENCES BETWEEN EPIMERS OF SOME I-N ALKYLATED KANAMYCIN A DERIVATIVES Data obtained from 1H noise-decoupled 13C spectra in Fourier transform mode on a silane as external standard.) Varian XL-100-15 spectrometer.(Samples in D,O, pD = 3; S relative to tetramethyl- Hydroxyaminobutyl kanamycin A Gly cery 1 Carbon I A , kanamycin A position (UK-18892), p.p.m. (UK-34688), p.p.m. AS, p.p.m. AS, p.p.m. 1 58.0 56.9 1.1 1.0 CI 51.4 50.7 0.7 0.8 66.3 65.4 0.9 0.8 26.7 26.4 0.3 0.3 P 2 6 84.5 84.3 0.2 (-0.1) 0.2 cm3 rnin-’ .II Proportionating pumR Technicon AutoAnalyzer I Waste, 0.23 cm3 min-’ 345 The three larger chemical shift differences have been exploited for some quantitative determinations of levels of UK-34688 in UK-18892.Spectra of mixtures were recorded under conditions that ensured equal response for corresponding nuclei in the two isomers. The intensity ratio for each of the three pairs of peaks gave the isomer ratio. The limit of detection for UK-34688 by use of this technique, was an isomer ratio of 0.05.However, owing to the relative unavailability of pulsed Fourier transform spectrometers for routine quality control functions, and the long accumulation times necessary for high sensitivity, it was felt that nuclear magnetic resonance would not be appropriate for routine analysis.The method of choice was HPLC, with a pellicular cation exchange stationary phase eluted isocratically. This method was developed from a chromatographic system already in use in our laboratories, which was based on a published assay of kanamycin A by HPLC.2 The chromatograph (Fig. 1) consists of a pulse-damped piston pump delivering eluting agent through a 1.5-m column of Zipax SCX coupled to a post-column derivatisation system.The earlier system, in which a 0.5-m column of Zipax SCX was used, had been coupled to the well Eluting agent, 0.18 M KzEDTA, pH 6.2, 0.2 crn3 min-’ Pump; Milton - Roy Minipump pressure 250 Ib inp2 Buffer, 0.1 rd K2EDTA, pH 10.5 0.32 cm3 min-’ Air. 0.32 cm3 min -’ T I h Pressure gauge, Acco- Helicoid Fltior 10 p1 Loop injection valve, SDectra- Phvsics Column 1.5 m x 2.1 mm i.d.stainless steel containing Zipax SCX Recorder Servoscribe 2 Spectrof luorir Perkin-E lmer fitted with de and flow-thro neter, 1000, -bubbler ugh cell. Out !Waste A,, = 380 nm, X, = 470 nm Fig. 1. High-performance liquid chromatograph for separations of UK-18892 and UK-34688. A, Splitter, Perspex and stainless steel, Technicon Part PT2, 116-B000; B, T-pieces, glass and stainless steel, Technicon Part A10; 116-B034; C, mixing coil, 10 turns x 20 mm radius, Technicon Part 116-0127-05; tubing and hydraulic connections, Swagelock stainless steel, Technicon Solvaflex and silicone connecting and pump tubing.346 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Proc.Analyt. Div. Chem. Soc. established ninhydrin detector.The increased column length gave adequate separation of the epimers and changing to the fluorescamine detector improved the time of analysis. The fluorescamine reaction3 has been widely applied as a rapid, sensitive assay for the primary amino group. Fluorescamine condenses with primary amines to form intensely fluorescent compounds, which are stable for several hours.The reaction is complete in less than 1 min, while fluorescamine is hydrolysed in a competing, but slower, reaction. The maximum signal to noise ratio for the chromatogram was obtained by carefully designing the layout of the AutoAnalyzer system and balancing the reagent flow-rates in order to achieve complete mixing and sufficient reaction time. Undue hydrolysis of the fluorescamine solution was prevented by protecting the solution (in dry acetonitrile) from atmospheric moisture and by adding the reagent last.The peristaltic pump (Fig. 1) delivers buffer in order to adjust the eluate to pH 9 for maximum fluorescence, then air to segment the stream and finally fluorescamine solution. The fluorescence was measured on a Perkin-Elmer, Model 1000, spectrophotometer, fitted with de-bubbler and 25-pl flow-through cell.It was shown that the detection system did not contribute to post-column band broadening of a relatively slow chromatogram such as this. Under these conditions UK-18892 was eluted first, with a retention volume of 9.6 cm3, while UK-34688 had a retention volume of 11.2 cm3. The separation factor, cc, was 1.3 and the efficiency, N, was 500 theoretical plates m-l for a freshly-packed column, falling to about 200 after several weeks’ use.The ratio of peak heights varied linearly with isomer - ratio UK-34688 between 0.025 and 0.20 (Table II), enabling the UK-34688 content of test UK-18892 samples to be measured by use of a calibration graph. TABLE I1 VARIATION OF HPLC PEAK HEIGHT RATIO WITH ISOMER RATIO FOR A SERIES OF SAMPLES OF UK-18892 SPIKED WITH KNOWN LEVELS OF UK-34688 Known isomer ratio in sample Amount UK-34688 Amount UK-18892 0.024 0.047 0.101 0.147 0.21 1 Peak height ratio Height UK-34688 Height UK- 18892 0.004 0.014 0.045 0.058 0.105 The limit of detection was an isomer ratio of about 0.02.The day to day reproducibility of the chromatograms was excellent provided that the exact chromatographic conditions were maintained.With a more efficient column improvements in accuracy and sensitivity should be possible. Microparticulate bonded-phase ion-exchange packings are currently under evaluation as potential alternative stationary phases. The HPLC system, therefore, proved suitable for routine determinations of UK-34688 in UK-18892 while CMR was valuable in elucidating the structure of the impurity.The two techniques were complementary in the solution of a difficult analytical problem. The author acknowledges the assistance of his colleagues in the Analytical Chemistry Department of Pfizer Central Research, from whose work this paper has substantially been drawn. References 1. 2. 3. Richardson, I<., Jevons, S., Moore, J.W., Ross, B. C., and Wright, J. R., J . Antibiot., 1977, 30, 843. Mays, D. L., van Apeldoorn, R. J., and Lauback, R. G., J . Chvornat., 1976, 120, 93. Udenfriend, S., Stein, S., Bohlen, P., Dairman, P., Leimgruber, W., and Weigele, M., Science, N.Y., 1972, 178, 871.December, 1978 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Analytical Aspects of the Chemistry of Cannabis 347 P.B. Baker and R. Fowler Laboratory of the Government Chemist, Cornwall House, Stamford Street, London, SE1 9NQ “Cannabis” and the other products of the Cannabis plant are the most frequently encountered drug substances submitted to the Laboratory of the Government Chemist by Officers of HM Customs and Excise. Identification is normally achieved by a combination of colour tests,l microscopy and thin-layer chromatography.2 More detailed examinations are carried out to ascertain the age and/or the origin of samples where this is of forensic i n t e r e ~ t .~ These operations require the use of an extensive reference collection based on samples submitted to the Laboratory over the past 10 years. It is sometimes necessary to compare two (or more) samples of cannabis in order to establish or refute a connection between the samples.The origin of a sample can be deduced by comparing the cannabinoids present in the sample in question with those present in samples of known origin. Age is determined by measuring the ratio of the approximate quantities of Ag-tetrahydrocannabinol (THC) , (I, R, = H, R, = C,H1,), and cannabinol (CBN), (11, R, = H, R, = C5H11), that are present in the sample of unknown age; this ratio is compared (by using thin-layer chromatography semi-quantitatively) with the ratio in samples of known age.CBN is formed from THC in an oxidation reaction proceeding over many months. kRl H3C kRl H3C & R1 ’ R2 H3C H3C 0 ‘ R2 H3C ‘ R2 H?C/HO I II Ill OH I V V Recent development work has concentrated on improving methods of comparison of cannabis samples; this is an aspect upon which members of staff, as expert witnesses, are most often questioned when giving evidence in court.Thin-layer chromatography2 was the original method and this has subsequently been improved to give increased resolution of the many compounds present in cannabis. Table I illustrates the system currently in routine use for the examination of cannabis sample^.^ This system gives a good separation of cannabidiol (CBD), (111, R, = H, R, = C5H,,), THC and tetrahydrocannabivarin (THV), (I, R, = H, R, = C,H,), but poor resolution of CBN and cannabivarin (CBV), (11, R, = H, R, = C,H,).The cannabinoid acids [these include tetrahydrocannabinolic acid (THCA) , (I, R, = COOH, R, = C5H,,), tetrahydrocannabivaric acid (THVA), (I, R, = COOH, R, = C3H,), cannabidiolic acid (CBDA), (111, R, = COOH, R, = C5H1,) and cannabigerolic acid (CBGA), (IV, R = COOH)] are not resolved by this system and run as an envelope of short retention (RF).Detailed comparison is made by thin-layer chromatography in two dimensions using 10 x 10 cm plates, run first in the above solvent mixture, dried, sprayed with diethylamine and then developed a second time at right angles to the first in xylene - dioxan (19 + 1 ) .The resolution of some 15-20 components is possible.* Although gas - liquid chromatography has been used for the separation of cannabinoids for many year^,^,^ it is limited in its value for comparative studies as the cannabinoid acids decarboxylate on the column to give the cannabinoids.Two typical chromatograms are shown in Fig. 1.348 ORIGINAL PAPERS ON PHARMACEUTICAL ANALYSIS Proc. Analyt. Div. Chem. Soc. TABLE I R, VALUES OF CANNABINOIDS Solvent system : alcohol-free chloroform - 1,l-dichloroethane (15 + 10) on Merck Kieselgel 60F2,, 5 x 10 cm plates (Merck Art 5719). Cannabinoid R F Colour * Cannabinoid acids 0.00-0.2 5 Cannabichromene (V) (CBC) 0.38 Cannabigerol (IV, R = H) (CBG) 0.41 THV 0.45 CBV 0.50 THC 0.55 CBN 0.60 CBD 0.63 Red - orange Purple? Orange Red Purple Red Purple Yellow * Made visible by spraying with diethylamine followed by 0.1 yo fast blue BB in methanol - water (3 + 1).t This colour changes to orange - brown in approximately 1 h. However, by using high-performance liquid chromatography (HPLC) , resolution at least as good as that obtained with thin-layer chromatography is achieved.In addition, a quantitative determination of the major constituents can be made and there is no danger of thermal degradati~n.~,~ Consequently, recent work has concentrated on developing HPLC methods for the separation of cannabinoids and the comparison of cannabis samples.Fig. 2 shows two typical chromatograms obtained by using a recently developed ~ y s t e m . ~ Fig. 1. Gas chro- matograms of extracts from two different can- nabis resin samples : (a), from Pakistan; ( b ) , from Lebanon. The peaks correspond to : A, CBD; R, Ag-THC; C, CBN. Conditions: column, 1.5 m x 4 mm i.d. glass, packed with 3% OV-17 on Gas- Chrom Q (100-120 mesh) : gas flow-rate, 30 ml min-l, oven temperature, 250 "C ; flame-ionisation detec- tor. E I II c I Fig. 2. Liquid chromatogram of an extract from a sample of cannabis resin from Pakistan. The peaks correspond to: A, CBD and CBV; B, THV and CBG; C, CBDA; D, CBN; E, THC; F, THVA; G, CBC; H, THCA and CBGA. Conditions: column, 25 cm x 4 mm i d . packed with Spherisorb S5 ODS; solvent, 0.02 N sulphuric acid - methanol - acetonitrile (7 + 8 + 9) ; flow-rate 1.2 ml min-l ; pressure drop, 1 075 lb in-2; detector, ultraviolet a t two wavelengths, (a) at 220 nm and (b) at 280 nm. Satisfactory separation of a number of cannabinoids is obtained under these conditions. It is clearly preferable, at least for the detection of the major components, to use a wave- length of 220 nm. Identification of the other separated components derived from cannabis is made by combining information from two-dimensional thin-layer chromatography and HPLC. A modification of the routine thin-layer chromatographic method involves heating the plate (5 min at 150 "C) after the first run, thereby decarboxylating the cannabinoid acids,December, 197’8 EQUIPMENT NEWS 349 and then making a normal second development.4 Combination of the results of this process with the known cannabinoid content of cannabis samples from the reference collection has made possible the identification of several minor cannabinoids and cannabinoid acids not recognised in HPLC reports by other workers.*,l0 Some eleven major components have now been identified and further identification of the minor components will be made by physical methods. In order to ascertain whether HPLC can be used as a valid forensic comparison technique, several studies are being carried out; the variation of the cannabinoid content from different parts of a block of cannabis resin, and the variation in the cannabinoid content of a number of blocks of the same origin, are being determined. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. References de Faubert Maunder, M. J., Bull. Narcot., 1969, XXI (4), 37. de Faubert Maunder, M. J., J . Pharm. Pharmac., 1969, 21, 334. de Faubert Maunder, M. J., Med. Sci. Law, 1976, 16, 78. Fowler, R., Gilhooley, R. A., and Baker, P. B., in preparation. Heaysman, L. T., Walker, E. A., and Lewis, D. T., Agzalyst, 1967, 92, 450. Parker, J. M., and Stembal, B. L., J . Ass. Off. Analyt. Chem., 1974, 57, 888. Wheals, B. B., and Smith, R. N., J . Chromat., 1975, 105, 396. Smith, R. N., J . Chromat., 1975, 115, 101. Fowler, R., and Baker, P. B., in preparation. Smith, R. N., and Vaughan, C. G., J . Chromat., 1976, 129, 347.

ISSN:0306-1396    

DOI:10.1039/AD9781500329

出版商:RSC    

年代:1978

数据来源: RSC

摘要:

December, 197’8 EQUIPMENT NEWS 349 Equipment News Automatic High-performance Liquid Chromatography System An automatically controlled detector and new software are now available on an enhanced version of the Hewlett-Packard 1084 micro- processor-based, high-performance liquid chro- matograph (HPLC). The new software (HP 79888A) of the enhanced HP 1084B enables the user to programme changes of separation parameters, calibration factors and calculation procedures. An automatic sampling system holds up to 60 samples.Wavelength combinations of the new HP 79875A ultra- violet - visible detector can be programmed to change automatically during one analysis or between analyses. Earlier HP 1084A models can be upgraded in the field if the added capabilities of the enhanced HP 1084B are required by present users.Hewlett-Packard Ltd., King Street Lane, Winnersh, Wokingham, Berkshire, RGl 1 5AR. Ultraviolet Detectors An accessory for the new SP8310 detector has been designed for installation in the micro- processor-controlled SP8000 liquid chromato- graph. Operation a t 254nm is standard, and optional wavelengths of 280, 312, 365, 436 and 546 nm are available. Full scale sensitivity ranges from 0.0025 to 1.28 absorbance unit.The detector cell has a volume of 10 pl. St. Albans, Hertfordshire, AL1 5UF. Spectra-Physics Ltd., 17 Brick Knoll Park, Ultraviolet Monitor An ultraviolet monitor with selectable wave- lengths is announced. While the standard wavelength is 254 nm, filter cassettes enable wavelengths of 195-360 nm t o be selected.The optics are single-beam, with reference compensator and the flow cell design minimises temperature and refractive index effects. Applied Chromatography Systems Ltd., Concorde House, Concorde Street, Luton, Bedfordshire, LU2 0 JE. Nuclear Magnetic Resonance Spectrometer The Model R-600 high-resolution, Fourier transform NMR Spectrometer provides a 14092 G field for proton observation at 60MHz. In combination with a micro- computer data system, the R-600 can obtain NMR spectra on amounts of 500 p g or less.High resolution spectra can be obtained by means of an internal deuterium field/frequency lock to a field stability within a few tenths of 1 Hz. The resolution of the system is 0.5 Hz, while the integration accuracy is 2.5% (with 5% ethylbenzene).Single-pulse or two-pulse sequence modes are offered, with pulse intervals from 0.8 to 100.0 s possible.350 EQUIPMENT NEWS Proc. Analyt. Div. Chem. SOC. Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Buckinghamshire, HP9 1QA. Atomic-absorption Spectrophotometer The Model 5000 is an automated atomic- absorption spectrophotometer capable of sequential multi-element analysis, which can automatically determine up to six elements in up to 50 samples.A magnetic card reader enters all of the operating conditions for six analyses, a six-lamp turret automatically selects the light sources, and background correc- tion in both the ultraviolet and visible ranges is included. Wavelength, slit width, electrical parameters, gas choice and flow-rate and calibra- tion are microcomputer controlled and can be programmed into the spectrophotometer mem- ory.Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Buckinghamshire, HP9 1QA. Fluorescence Spectrometers Two new models, the Model 2000 fluorescence spectrophotometer and the Model 1OOOM filter fluorimeter are announced. The Model 2000 has a microprocessor controlled scanning emission monochromator, enabling emission spectra to be scanned automatically over the range 390-750nm.The Model lOOOM filter fluorimeter is a non-scanning version of the Model 2000. Both instruments use a strobo- scopic xenon source in order to provide a continuum of energy over the range 260- 650 nm. Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Buckinghamshire, HP9 1QA.Automatic Analyser The Model DIMA 12 automatic chemical analyser has been designed for the analysis of trace elements and a wide range of organic species in water, waste-waters, effluents and industrial solutions. The instrument carries out on-line liquid - liquid extraction with either a heavier or lighter immiscible solvent, which results in a con- centration of the analyte by approximately a factor of 10.The samples are then analysed by a high sensitivity photometric method. The limits of sensitivity that can be achieved include heavy metals (copper, cobalt, iron, uranium, etc.) in the 1-10 p.p.b. range and detergents in the 0.5-5 p.p.b. range. Up to four reagents in addition to the extractant can be used in the colour-generating reaction. EDT Research, 14 Trading Estate Road, London, NWlO 7LU.Autosampler for Liquid Chromatography A liquid chromatography autosampler, designed for use with the recently introduced SP8000 high-pressure liquid chromatograph, is micro- processor-controlled by the SP8000. The new Spectra-Physics Autosampler accommodates up to 210 samples in multiple test-tube racks. Each tube can be covered by a thin plastic cap in order to prevent evaporation and the release of toxic vapours ; airborne contaminants are also excluded.Spectra-Physics Ltd., 17 Brick Knoll Park, St. Albans, Hertfordshire, AL1 5UF. Valves for Liquid Chromatography A recently announced range of check valves for high-pressure liquid chromatography uses a new elastomer with very wide chemical resistance to provide a liquid-tight seal at low back pressures and to minimise seal wear; the valves operate a t high pressures, up to 15 000 lb in-2.Scientific Glass Engineering (UK) Ltd., 657 North Circular Road, London, NW2 7AY. Differential Scanning Calorimeter A new model, the TA2000M, has been designed as an alternative to the TA2000A and B versions. The TA2000M has a low tempera- ture facility, similar to those available on the TA2000B.The basic components of the TA2000M are the same as those of the A and B versions but the TA 11 measuring cell is cooled by the new Mettler 27800 compressed- a k attachment. This unit eliminates the need for liquid nitrogen and allows a TA2000M user the option of expanding the working range down to -170 "C. A new version of the TA2000 thermoanalyser, the TA2000C, makes possible simultaneous differential scanning calorimetry and thermo- gravimetry.To complement the TA2000 range, the TA2000Z automatically evaluates test data and increases automation by utilising feedback control from a desk-top computer. A. Gallenkamp & Co. Ltd., P.O. Box 290, Technic0 House, Christopher Street, London, EC2P 2ER. High-voltage Power Supply A high-voltage power supply designed to fit round the neck of a triple-mode X-ray image- intensifier tube is now available.The Branden- burg Model 831, which operates from a +24 V d.c. input, has the following outputs: anode, +30 kV at up to 3 PA; getter, 2.5 kV at up to 20 PA; grid 1 (multi-range), +75 to +450 V each range at up to 2 PA; grid 2 (multi-range),December, 1978 EQUIPMENT NEWS 351 +400 to +900 V each range at up to 1 pA; grid 3 (multi-range), 2.85-3.35, 6.45-6.95 and 10.2-10.85 kV a t up to 1 pA.Brandenburg Ltd., High Voltage Engineering, 939 London Road, Thornton Heath, Surrey, CR4 7JE. Laboratory Automation Systems Two disc-based laboratory automation systems are announced, designated HP3354B and HP3354C. The turnkey computer systems can interface with up to 45 analytical instruments, with up to 30 of these being analogue to digital converters. Concurrently, the systems can collect and evaluate real-time data from gas and liquid chromatographs and control liquid samplers.The systems differ only in the housings. The hardware for the basic HP3354B/C system consists of an HP21MX E-series com- puter with 32K bytes of memory, a new HP 7906 20-megabyte disc drive, a 240-LPM printer, one instrument interface and an HP2645A CRT terminal with built-in dual cartridge tape transports.Hewlett Packard Ltd., King Street Lane, Winnersh, Wokingham, Berkshire, RG11 5AR. Chart Recorders The BS600 series of flat-bed chart recorders has been introduced recently, with a dynamic pen response of 0.25 s for a full-scale deflection of 250mm.Sixteen chart speeds from 2cmh-l to 60cmmin-l are provided by a stepping motor with a chart speed resolution of 150 steps cm-l, and 12 input ranges from 1 mV to 1OV f.s.d. are available for the general purpose model. A further version provides single range inputs specifically for O.E.M. use. The recorders are available in either single- or two-channel versions and are supplied with rechargeable fibre-tipped pens.Bryans Southern Instruments Ltd., Willow Lane, Mitcham, Surrey, CR4 4UL. Disposable Pen System The Series 10 stretch disposable pen and pen arm is designed to fit three popular models of Foxboro strip-chart recorders (Model Nos. 53, 54 and 6400), replacing the conventional pen and capillary ink cartridge system with a fibre-tip disposable pen.The Series 39 fibre-tip disposable marking system is also available for circle-chart recorders. Graphic Controls Ltd., P.O. Box 774, Clyde Vale, Forest Hill, London, SE23 3JQ. Digital Thermometer The Anwill Tempcheck liquid crystal display digital thermometer has been designed for practical field use where laboratory accuracy is necessary, and it is capable of measuring temperature ranges between absolute zero (-273 "C) and plus 1 999 "C.The thermometer is supplied with either a chrome - alumel probe for surface temperature readings or alternatively a chrome - alumel probe with a sealed stainless-steel sheath for use with liquids or gases; the latter is suitable for food trade applications. Anwill Instrument Co., 26 Knowles Street, Rishton, Hyndburn, Lancashire.Electrophoresis Cell The Model 1120 Super Slab electrophoresis cell is primarily designed for DNA sequencing and has gel size of 33 x 43cm. The standard sample comb of 13 x 10 x 1.5 mm gives a sample volume of 195 p1. Bio-Rad Laboratories Ltd., Caxton Way, Holywell Industrial Estate, Watford, Hert- fordshire. WD 1 8RP. Electrolyte Measurement Sodium and potassium measurements are performed in the Orion Space-Stat 30, a sodium/ potassium analyser that is completely self- contained and provides sodium and potassium results within 1 min of sampling in any location.MSE Scientific Instruments, Manor Royal, Crawley, Sussex. Automatic Cyanide Monitor A new automatic monitor can measure the total cyanide content of liquid samples down to concentrations of 30 pgl-1 (30 p.p.b.).Free cyanide is complexed and measured by ultra- violet spectrophotometry, the sample is then subjected to ultraviolet irradiation in order to destroy cyano complexes and the liberated cyanide again measured by ultraviolet spectro- photometry, thus giving the total cyanide content of the sample. The reagent used is specific for cyanides, thus preventing any interfering effects.EDT Research, 14 Trading Estate Road, London, NWlO 7LU. Microscope Optics New Microscope optics now available include objectives with international standard thread 36 t.p.i. (1.42-1 mm) and eyepieces mounted in barrels of international standard 23 mm diameter. The microscope objectives have magnifying powers from 1 : 1 to 100: 1, with352 EQUIPMENT NEWS Proc.Anabt. Div. Chew. SOC. numerical apertures from 0.05 to 1.25. The flat field models are capable of resolving 1-pm lines. The selection of eyepieces consists of Huygens, Ramsden and wide field Kellner types with magnifying powers from 4 x to 2ox. All models can be equipped with standard 21-mm graticules. Melles Griot B.V., Industrial and Scientific Optics, Nieuwe Kade 10, Postbus 567, Arnhem, Netherlands.Adjustable Sampler The new Oxford adjustable samplers cover the range 2-1 000 p1 in four instruments. Cata- logue numbers 3001, 3002, 3003 and 3004 cover the working range 2-10, 10-50, 50-200 and 200-1 000 pl, respectively. The design is based on the P700 fixed volume sampler. The Boehringer Corporation (London) Ltd., Bell Lane, Lewes, East Sussex, BN7 1LG. High Impedance Millivoltmeter for pH Measurement Designated the Model LTD90, this new pH meter is a high impedance millivoltmeter with an accuracy of 0.01% of reading f last digit, and is intended for use with redox or ion- selective electrodes.Up to 60 h of inter- mittent or 35 h continuous use is possible from the Type MN1500 batteries that are fitted as standard, and optional Type AA rechargeable batteries can also be supplied.Lenton Thermal Designs Ltd., 68 Cannock Street, Leicester, LE4 7HR. pH Meter First to be released in the 6000 series of pH meters is the Model 6060, which provides accurate pH measurement over the range 0-14 pH to a resolution of 0.1 pH. Full automatic temperature compensation over the range 0-100 "C is effected by a high-accuracy plati- num resistance probe.Up to 60 h of inter- mittent or 35 h continuous use is provided by MN 1500 batteries ; Type AA rechargeable batteries and a charger are offered as an option. The Model 6060 pH meter is supplied with a steel-bodied temperature compensation/ measurement probe, plus either a plastic- bodied pH electrode, for liquid applications, or a plastic-bodied combination electrode with a pointed, toughened-glass tip, for pH measure- ment in semi-solids such as meats, cheeses, soils, etc.Jenway Ltd., 26 Broomhills Industrial Estate, Raines Road, Braintree, Essex. Disposable Chemical Cartridge Filter The "Fluorex" Cartridge is a filter unit con- sisting of either a 0.2 or a 1.0 pm PTFE membrane sandwiched between extruded poly- propylene support screens.The sandwich is pleated and wrapped around a porous poly- propylene core, providing a large surface area in a small volume. Utilising the pleated con- cept, a filtration area of 929cm2 has been achieved in a small disposable housing no larger than 7.6 cm in diameter and 12.7 cm in depth overall. The use of PTFE and poly- propylene in the construction allows wide chemical compatibility.The filter can equally be used for gases and is not subject to any blockage due to deposits of water. Millipore (UK) Ltd., Milipore House, Abbey Road, London, NWlO 7SP. Flow Sensor The Annubar now announced is a diamond- shaped primary flow sensor designed to produce a differential pressure that is proportional to flow, for measurement of liquids, gas and steam in pipes, stacks or rectangular ducts. It is available in line sizes from 1 in to over 30 ft.Accuracy is &l.O% of the actual value, and repeatability is +0.1% of the actual value. AEP International Ltd., Victor House, hTorris Road, Staines, Middlesex. Oscillographic Recorders The CRT recorder is based on fibre optics, with self-contained signal conditioning.Recording is inertialess. Honeywell Ltd., Industrial Products Group, Charles Square, Bracknell, Berkshire. Electronic Balance The Series 1200 MP single pan top-loading balances provide analogue and BCD outputs, have a built-in vibration filter and automatic overload protection. Sartorius Instruments Ltd., 18 Avenue Road, Belmont, Surrey. Thermostat Bath Now available is a high-precision, laboratory, general-purpose thermostat bath, with a temperature control accuracy of fO.01 "C over the range 10-120OC.The unit, Type E270 Series 4, meets the exacting standards of BS188 and IP71/75. Armour-plated inside windows and boost heating by automatic or manual control are incorporated. For viscometry work, holder accessories ensure that the viscometers are maintainedDecember, 1978 EQUIPMENT NEWS 353 vertically in the bath, with clear sight of the liquid meniscus and avoidance of temperature fluctuations.Townson & Mercer Ltd., 101 Beddington Lane, Croydon, Surrey, CR9 4EG. Spectroscopic Analysis System A multi-channel analyser, featuring multiple- processor technology, independent data memories and an interactive operator’s control console has been introduced.The basic TN-4000 System provides qualitative and semi-quantitative spectral analysis. Complete software packages, providing automated, quantitative analysis, are available for neutron activation analysis and gamma-ray spectro- scopy. Tracor Northern Inc., 2551 West Beltline Highway, Middleton, WI 53562, USA. Atomic-absorption Spectrophotometers The Model 560 is an improved version of the Model 460 microprocessor-based double-beam atomic-absorption spectrophotometer, which makes possible complex calculations and imple- ments sophisticated logic programmes quickly and accurately.The Model 560 features a new dual-blazed grating, which permits opti- mum photometric response throughout the wavelength range with a single grating.Automatic calibration with up to three standards for wide dynamic range enables integrated readings in absorbance, concentra- tion, or emission intensity to be obtained in from 0.2 to 60s. The model can be used for flame or flameless atomic absorption. The Model 703 is an improved version, combining the optical system and electronics system of the Model 603 with an improved computing ability.Model 703 automatically calibrates with one, two or three standards, as well as providing automatic curve correction in the absorption or emission mode for flame or flameless sampling with variable integration times for 0.2 to 60 s and variable scale expan- sion from 0.01 to 1OOx. Included as options are pushbutton gas controls and a deuterium arc background corrector with background-only mode.Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Buckinghamshire, HP9 1QA. Fluorescence Spectrophotometer Thc Model 650-10 is a high-performance, liigh- sensitivity fluorescence spectrophotometer with an optical design providing increased energy at narrow spectral band pass levels and an ozone-free xenon source. With a continuously variable slit for both nionochromators, six scan speeds, linear gain adjustments and zero suppression for elimination of fluorescence background from sample blanks that fluoresce, the instrument can accommodate liquid chroma- tographic flow cells for both quantitative and qualitative identification of chromatographic fractions with an 18- p1 flow-through microcell. It requires only 0.6 ml sample volume for standard cells.The wavelength readout is accurate to within &2 nm. Perkin-Elmer Ltd., Post Office Lane, Beacons- field, Buckinghamshire, HP9 1QA. X-ray Fluorescence Chemical Analyser The PGT Model 100, a push-button analyser, can measure up to three pre-defined elements simultaneously by means of X-ray fluorescence. With a minimum of sample preparation it can analyse samples in liquid, solid or powder form, in from 10 to 200 s, depending on the accuracy required.Micro-electronic printed circuit boards that sort and compute data can be supplemented or re-tuned to analyse different chemical elements from those which are initially pre-set. PGT International, 2 Meadow Walk, Great Abington, Cambridge. Ultraviolet - Visible Spectrophotometer The Spectracomp 601 includes total automation incorporating a programmable computer.The instruments’ parameters, time, date and temperature, and spectral data accumulation for as many as 500 wavelengths, are available as print-outs. A standard TTY output, magnetic stirring of the sample and reference cuvettes, thermostatic control of samples and digital readout of temperature are also pro- vided.Erba Science (UK) Ltd., 14 Bath Road, Swindon, Wiltshire, SN1 4BA. Capillary Gas Chromatograph The FV 2902 capillary column gas chromato- graph can be used with split, splitless or on- column injectors, single or dual columns, a range of detectors, a fast response electrometer, a large volume column oven with easily removable front door, digital temperature settings, readout connections for a mass spectrometer and a facility for ambient and sub-ambient operation.Erba Science (UK) Ltd., 14 Bath Road, Swindon, Wiltshire, SN1 4BA.354 EQUIPMENT NEWS PYOC. Analyt. Div. Chem. SOC. Electron-capture Detector for Capillary Columns A micro-volume electron-capture detector, suitable for use with capillary columns, is announced.A very low internal dead volume of only several hundred microlitres, a minimum detection limit equal to that obtained from packed columns and greatly increased resolu- tion are features of this instrument. The micro electron-capture detector uses a 10 mCi nickel- 63 source and has a usable upper temperature limit of 300 "C. With the electron-capture detector control module, operating conditions of constant current or constant period, both with variable amplitude, pulse width and pulse period, or direct current (0-50 V, continuously variable) are available.When used on a Carlo Erba FV 2151 AC gas chromatograph with a 20-m glass Jaeggi capillary column, an aldrin peak of 55% of f.s.d. from 45 pg a t an attenu- ation of x 512 is obtainable. Erba Science (UK) Ltd., 14 Bath Road, Swindon, Wiltshire, SN1 4BA.Blood Analyser The Microblood Analyser gives an actomatic printout of seven parameters in 1 min on a 10- pl sample. Erba Science (UK) Ltd., 14 Bath Road, Swindon, Wiltshire, SN1 4BA. Elemental Analyser The new elemental analyser, Model 1106, for carbon, hydrogen, nitrogen, oxygen and sulphur analyses can perform up to 100 analyses auto- matically with automatic switching between C, H, N and 0 or C, H, N and S.Erba Science (UK) Ltd., 14 Bath Road, Swindon, Wiltshire, SN1 4BA. Nitrogen Analyser The nitrogen analyser, Model 1400, is fitted with an automatic, 50-seat sampler and analyses a sample in only 5 min, giving a print- out of the nitrogen content in micrograms. Erba Science (UK) Ltd., 14 Bath Road, Swindon, Wiltshire, SN1 4BA.Total Carbon Monitor The total carbon monitor, Model 400P, is capable of detecting 0.1 p.p.m. of carbon in effluents and waters. Samples can be intro- duced automatically or manually. Erba Science (UK) Ltd., 14 Bath Road, Swindon, Wiltshire, SN1 4BA. Porosimeter The mercury pressure Porosimeter, Series 200, with digital readout and printout, is used with the Sorptomatic 1800 Series for surface area analysis and pore size distribution, and the Sorpty for rapid surface area determinations. Erba Science (UK) Ltd., 14 Bath Road, Swindon, Wiltshire, SN1 4BA.Protein Analyser LKB 2117 Multiphor system is now available with kits for analytical electrofocusing, pre- parative electrofocusing in granulated gel, and immuno-, SDS, agarose and polyacrylamide gel electrophoresis.LKB Instruments Ltd., 232 Addington Road, South Croydon, Surrey, CR2 8YD. Argon Jet for Plasma Spectrometers Spectrajet 111, a three-electrode argon jet for plasma-emission spectrometers, incorporates two graphite anodes and a tungsten cathode in an inverted Y configuration. The three elec- trodes are moved into contact by argon- actuated pistons, and plasma ignition is initiated automatically without a high-voltage spark as the electrodes are withdrawn.The Y configuration stabilises the position of the plasma and the sample excitation area. The Spectrajet I11 will be a standard feature on the Spectraspan I11 and IV spectrometers and can be fitted to all existing installations. Techmation Ltd., 58 Edgware Way, Edgware, Middlesex, HA8 8JP.Ion Beam Thinning Unit An ion beam thinning unit, the super Microlap, is announced. It incorporates two water- cooled, saddle-field, ion sources, Model B1 lW, to produce ion beams ranging in intensity from a few microamperes to 500 pA per source. At maximum power the two BllW ion sources will each produce an ion current density of 16 mA cm-2 on the specimen.Sensitive speci- mens can be mounted on a water-cooled or liquid nitrogen cooled stage. Torr, while the rotating specimen stage remains in the plane of focus of a binocular microscope in order to enable the process to be terminated by visual monitoring or automatic ion beam termination. Ion Tech Ltd., 2 Park Street, Teddington, Middlesex, TW 11 OLT. The saddle-field ion sources operate a t pH Meter The PW 9410 pH meter has been designed for routine pH measurement and simplicity in use, while incorporating the latest electronic cir-December, 1978 EQUIPMENT NEWS 355 cuitry in order to ensure reliable and repro- ducible results.N.V. Philips Gloeilampenfabrieken, Eind- hoven, Netherlands. Plastic-bodied Combination pH Electrode The Model 1180-2 features a thermally stable, chemically resistant plastic body, which extends to protect the sensitive glass pH membrane.It gives a rapid response to changes over the full 0-14 pH range for temperatures of 0-100 "C, and has a sealed, gel-filled reference, giving a long maintenance-free life. It can be supplied to fit any pH meter. Electronic Instruments Ltd., Hanworth Lane, Chertsey, Surrey.Homogenisers - Tissue Grinders The laboratory homogenisers are made from precision-bore tubing and incorporate a machined PTFE pestle and a stainless-steel shaft. The full range covers from 2 to 50 cm3. Valtech Plastics, Castlegarth Works, Thirsk, North Yorkshire, YO7 1PS. Microscope A new addition to the MI7 microscope range, the MI7 Koehler type laboratory microscope, is designed for the routine hospital laboratory and as a medium range version for biological research work.Plan-achromatic objectives and 20mm wide field eyepieces are standard, with flat-field apochromat objectives available for exceptionally high performance. Light is supplied by the 12 V, 20 W tungsten - halogen Koeliler type illuminator, which is equipped with a brightness control and meter.An extensive range of accessory items are available, including automatic camera units, drawing attachments and a projection head. Vickers Instruments Ltd., Vickers House, Millbank Tower, London, SWlP 4RA. Filter The 3.0 pm Fluoropore (PTFE) membrane filter consists of a thin PTFE matrix supported with non-woven polypropylene. It will with- stand almost any chemical, is thermally stable to 150 "C and is available in all standard diameters from 13 to 293 mm.Millipore (UK) Ltd., Millipore House, Abbey Road, London, NWlO 7SP. Portable Burner A portable laboratory burner with its own energy source is announced. The Labogaz gives a flame temperature of 1100 "C and a calorific output of 2 600 btu. A burner off- take of 60 Q h-l at an ambient temperature of 20 "C (68 O F ) gives approximately 3 i h burning time from the disposable C200 cartridge.Accessories available include a tripod and a fishtail burner. Camping Gaz (GB) Ltd., 126/130 St. Leonards Road, Windsor, Berkshire. New Materials Radioimmunoassay Materials Materials for the radioimmunoassay method of assaying testosterone and dehydrotestosterone, together with details of a novel method, are now available.The Radiochemical Centre, White Lion Road, Amersham, Buckinghamshire, HP7 07B. The Quantimune Digoxin RIA test system, based on the solid-state support technique using Immuno-beads as the support, is announced. The sensitivity and precision of the system are excellent throughout the test range and inter-laboratory and inter-operation variability is low.BioRad Laboratories Ltd., Caxton Way, Holywell Industrial Estate, Watford, Hert- fordshire, WD1 8RP. A kit for the radioimmunoassay method for TSH in human serum is announced. The Radiochemical Centre, White Lion Road, Amersham, Buckinghamshire, HP7 07B. Cross-linker for Solubilisable Electro- phoresis Gels A new cross-linking agent, bisacrylylcystamine, forms gels which have normal electrophoretic properties and which are soluble in the presence of 2-mercaptoethanol under conditions that do not degrade RNA.Bio-Rad Laboratories Ltd., Caxton Way, Holywell Industrial Estate, Watford, Hert- fordshire, WD1 8RP. Powdered pH Standards Now available are pH standards traceable to NBS values, in powdered form and contained in labelled glass vials.Freshly prepared solu- tions simply require dissolution in 100 ml of distilled or de-ionised water for use. Chemplex Industries Inc., 140 Marbledale Road, East Chester, NY 10707, USA. CRP Slide Test A new C-reactive protein (CRP) latex slide test is announced. Serum inactivation is not356 EQUIPMENT NEWS Proc. Analyt. Div. Chem. SOC. required, and lipaemic or haemolysed speci- mens do not interface. The Boehiringer Corporation (London) Ltd., Bell Lane, Lewes, East Sussex, BL7 1LG.Spectroradiometric Standards Three lamp standards (45-, 200- and 1 000-W), based on the National Bureau of Standards scale of spectral irradiance, are available with calibrations of spectral irradiance (W cm-2 nm), total irradiance (W cm-2) and illumination (footcandles).Glen Creston Instruments Ltd., 16 Carlisle Road, London, NW9 OHL. Literature A technical application brochure, the Ion Beam Microsputtering of Thin Films brochure, is available that details sputter deposition of alloys, sputter thin films and substrate prepara- tion techniques available to both the research and production thin film worker. Ion Tech Ltd., 2 Park Street, Teddington, Middlesex, TWll OLT.Five application sheets illustrate the use of the Scot capillary columns for the analysis of amino acids, sherry wine, fatty acid methyl esters, urinary steroids and the pyrolysis products of polyethylene. S.G.E., 657 North Circular Road, London, NW2 7AY. The AutoAnalyst, Clinical Edition, May, 1978, features SMAC correlation studies in Sweden. The Industrial Edition, May, 1978, includes an article on the AutoAnalyser System Manager.Technicon Instruments Co. Ltd., Evans House, Hamilton Close, Basingstoke, Hampshire. An eight-page colour brochure describing the Model TGS-2 thermogravimetric system is now available. A single page discussion of con- venience features is followed by three pages of performance data, supported with nine examples of sample runs showing : thermal separation characterisations ; oxidation analysis ; moisture analysis ; thermomagnetometry ; and a simul- taneous analysis with Perkin-Elmer’s DSC-2 differential scanning calorimeter.Perkin-Elmer Ltd., Post Office Lane, Beaconsfield, Bucking- hamshire, HP9 1QA. Two leaflets describe histopathology instru- ments, the Autoslip automatic coverslipper, a fully automated coverslipper for use with standard glass coverslips and mountant, and the 2L MK 11 automatic tissue processor. Shandon Southern Products Ltd., 93/96 Chad- wick Road, Astmoor Industrial Estate, Run- corn, Cheshire.A catalogue showing the current range of Virtis freeze dryers and accessories is available. Techmation Ltd., 58 Edgware Way, Edgware, Middlesex.Two visual-aid handbooks on capillary column chromatography are available. The first shows the fitting of a Grob-type split-less injector to a Carlo Erba chromatograph in order to achieve an all glass system through from injector to detector with no adaptors or connectors. The second visual aid shows the fitting of a capillary column to the FV2151 and to the FV2900, which is a new capillary column gas chromato- graph.Erba Science (UK) Ltd., 14 Bath Road, Swindon, Wiltshire, SN1 4BA. Details of the range of low-cost infrared spectrophotometers have now been published in a new colour brochure. The 12-page brochure offers extensive data on the SP1025, SP1050, SPllOO and SPllOOES instruments and details the combinations of features that are offered. Pye Unicam Ltd., York Street, Cambridge.A general catalogue is available covering pro- ducts in the nuclear spectroscopy [Ge(Li), NaI, surface barrier], X-ray (EDS - WDS full quanti- tative), medical (evoked response), optical (ultraviolet - visible - near infrared spectro- scopy system) and general signal averagers (NMR, EPR, Mossbauer and electron spectro- scopy) fields. Tracor Northern, 2551 West Beltline Highway, Middleton, WI 53662, USA. A chromatography technical bulletin “SP4000 ; An innovative Multi-Data System for Chromato- graphy,” describes features and applications of the SP4000 Data System. The sixteen-page publication illustrates the accuracy and speed of data processing from as many as sixteen gas and/or liquid chromatographs. Spectra- Physics, 17 Brick Knoll Park, St. Albans, Hertfordshire, AL1 5UF. A brochure describing the scintillation cocktails Pico-fluor 15, Pico-fluor 30, Insta-gel, Insta- fluor and Dimilume 30, and their application, contains also information for the biochemical laboratory such as sample preparation of nucleotides, proteins and TCA precipitates. Packard Instrument Ltd., Caversham Bridge House, 13-17 Church Road, Caversham, Berk- shire, RG4 7AA.December, 1978 HAZARD IN A KJELDAHL NITROGEN DETERMINATION 357 A six-page application note AN 228-4 (Publica- tion No. 5952-5771), entitled “Applications and Operation of the Nitrogen - Phosphorus Detector,” illustrated with sample chromato- grams and tables, describes the operation of the nitrogen - phosphorus detector in various applications, including clinical chemistry and toxicology, biomedical research, pesticide con- trol and food chemistry. Hewlett-Packard Ltd., King Street Lane, Winnersh, Wokingham, Berkshire, RG11 5AR. A 14-page catalogue describes various portable and bench optical measuring instruments including toolmakers, travelling and co-ordinate measuring microscopes and length measuring components. Graticules Ltd., Sovereign Way, Tonbridge, Kent, TN9 11iN.

ISSN:0306-1396    

DOI:10.1039/AD9781500349

出版商:RSC    

年代:1978

数据来源: RSC

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December, 1978 HAZARD IN A KJELDAHL NITROGEN DETERMINATION New British Standards BS 3900: Methods of test for paints. BSI has published three further parts, and a revision of an existing part. Two of the new documents relate to flashpoint testing. Part A13, “Rapid Test for Determination of Danger Classification by Flashpoint,” specifies a method of determining whether a paint, varnish, paint medium or relatcd product gives off sufficient flammable vapour to ignite, at a temperature of 0-105 “C, under test conditions.It is identical with IS0 3680. Part A14, “Rapid Test for Determination of Flashpoint,” specifies a method of determining the actual flashpoint of these materials over the same temperature range. It is identical with IS0 3679. The apparatus used in both tests enables a more rapid procedure and a smaller test portion to be used than is possible with the alternative closed-cup method tests that are specified in Parts A8 and A9.However, the 357 latter are being retained for the present as they are still quoted in government regulations. The third new document is Part C8, “Print- free Test,” which specifies a simple empirical test for assessing the resistance of a coat of paint, varnish or related product to imprinting by a nylon gauze under a specified force, applied for a given time.It is identical with IS0 3678. The revised issue is Part D1, “Visual Com- parison of the Colour of Paints,” which was originally based on Ministry of Defence stan- dards and has now been made identical with IS0 3668. Copies of BS 3900 Parts A13 and D1 (price L1.90 each), Part A14 (price L2.60) and Part C8 (price L1.40), can be obtained from BSI Sales Department, 101 Pentonville Road, London, N1 9ND.358 ANALYTICAL CHEMISTRY TRUST FUND Proc.Analyt. Div. Chem. SOC. BS3145: New Specification for Laboratory pH Meters. This standard now deals with all types of laboratory pH meters in current production, including the moving coil type, the automatic (servo-driven) potentiometric type and the more recently developed digital display type.Parti- cular attention has been paid to the errors of the meters (they arise from twelve sources) and the requirements are based on electrical perform- ance. The new standard deals with definitions, presentation of the measured quantity, scale, errors of indication, input current, stability, glass electrode input, temperature compensating devices, set buffer adjustment and slope-factor adjustment, and summarises the information to be given in literature provided.Test methods included are for errors of indica- tion, for the determination of over-all instru- ment error, for input current and for isopoten- tial and temperature compensation.These com- pliance tests have been designed with typical usage of glass and reference electrodes in mind but simulated conditions are used to make the tests independent of electrode performance. In preparing this new standard an extensive survey of pH meters in current production was undertaken. The result is a set of practicable requirements, prefaced by a Foreword that is helpful in indicating the sources of some com- mon, though not widely appreciated, causes of inaccuracy in the use of pH meters.Copies of BS 3145, price L3.20, can be ob- tained from BSI Sales Department, 101 Penton- ville Road, London, N1 9ND. BS 5598: Methods of Sampling and Tests for Halogenated Hydrocarbons. Part 1. Sampling of Liquid Products. This standard is concerned with products intended as raw material for paints and varn- ishes. It incorporates the text of IS0 2209. Methods are described for sampling from small containers, such as drums and cans, and from bulk containers such as cylinders and tanks. A method of continuous sampling during trans- fer of the product by pipeline is also specified. BS 5598 Part 1, price fT1.90, can be obtained from BSI Sales Department, 101 Pentonville Road, London N1 9ND.

ISSN:0306-1396    

DOI:10.1039/AD978150357b

出版商:RSC    

年代:1978

数据来源: RSC

摘要:

358 ANALYTICAL CHEMISTRY TRUST FUND Proc. Analyt. Div. Chem. SOC. Water Research Centre Technical Reports The following recently produced reports are available from the Water Research Centre Medmenham Laboratory (Medmenham, P.0. Box 16, Marlow, Buckinghamshire, SL7 2HD) or Stevenage Laboratory (Elder Way, Steven- age, Hertfordshire, SG1 1TH). TR70 WRC Porous-pot Method for Assess- ing Biodegradability TR75 Determination of Anionic Surfact- 1 ants Within a Concentration RangeDecember, 1978 PUBLICATIONS RECEIVED 0-1.0 mg 1-1 in Sewage Effluents and Waters by Autoanalysis TR76 Manual and Automated Gas-chroma- tographic Procedures for the Deter- mination of Volatile Fatty Acids TR81 Multi-element Analysis of Drinking Waters TR82 The Measurement of Chlorophyll TR85 Chromatographic Analysis of Diges- ter Gases 359

ISSN:0306-1396    

DOI:10.1039/AD978150358b

出版商:RSC    

年代:1978

数据来源: RSC

摘要:

December, 1978 PUBLICATIONS RECEIVED 359 Publications Received Manual of Chemical Methods for Pesticides and Devices, and First Update (1977). U.S. Environmental Protection Agency. Washington, D.C. : Association of Official Analytical Chemists. 1976. Loose-leaf format. The Donor - Acceptor Approach to Mole- cular Interactions. Viktor Gutmann. Pp. xvi + 279. New York and London: Plenum. 1978.Price $33.00. Introduction to X-Ray Spectrometric Analysis. Eugene P. Bertin. Pp. xiv + 485. New York and London: Plenum. 1978. Price $34.20. Chromatography of Synthetic and Biologi- cal Polymers. Volume 2. Hydrophobic, Ion Exchange and Affinity Methods. Edited by Roger Epton. Pp. x + 353. Chichester : Ellis Horwood. Distributed by John Wiley in Europe, Africa, Canada, Aus- tralasia and South-east Asia and by Halsted Press in North and South America and the rest of the world.1978. Price f118.50. Particle Size Analysis. Proceedings of a Conference organised by The Analytical Division of the Chemical Society and held at the University of Salford, 12-15 Septem- ber, 1977. Edited by M. J. Groves. Pp. xii + 492. London, Philadelphia, Rheine : Heyden. 1978.Price f130; $60; DM192. Topics in Enzyme and Fermentation Bio- technology. Volume 2. Edited by Alan Wiseman. Pp. 308. Chichester : Ellis Horwood. Distributed by John Wiley, Chichester. 1978. Price L15. Environmental Pollutants : Detection and Measurement. Edited by Taft Y. Toribara, James R. Coleman, Barton E. Dahneke and Isaac Feldman. Environmental Science Research, Volume 13.Pp. xii + 500. New York and London: Plenum. 1978. Price $51. Neutron Inelastic Scattering 1977. Pro- ceedings of a Symposium on Neutron Inelastic Scattering held by the Inter- national Atomic Energy Agency in Vienna, 17-21 October, 1977. Volumes I and 11. Proceedings Series, STI/PUB/468. Volume I, pp. xiv + 649; Volume 11, pp. xii + 556. Vienna : International Atomic Energy Agency.Available in the UK from HM Stationery Office. 1978. Price: Volume I, $52; Volume 11, $44. Dioxin : Toxicological and Chemical Aspects. Edited by Flaminio Cattabeni, Aldo Cavallaro and Giovanni Galli. Monographs of the Giovanni Lorenxini Foundation, Volume 1. Pp. xiv + 222. New York and London: SP Medical and Scientific Books. Distributed by Halsted Press, New York. 1978. Price Ll4.50; $26.50.Computers in Mass Spectrometry. J. R. Chapman. Pp. x + 265. London, New York and San Francisco: Academic Press. 1978. Price f19.80. Enzyme Engineering. Volume 3. Edited by E. Kendall Pye and Howard H. Weetall. Pp. xiv + 580. New York and London: Plenum. 1978. Price $47.40. Physical Chemistry and its Biological Applications. Wallace S. Brey. Pp. xii + 589. New York, San Francisco and London : Academic Press. 1978.Proceedings of the 1976 International Conference on Modern Trends in Activa- tion Analysis, Munich, Federal Republic of Germany, 13 to 17 September, 1976. Volumes I and 11. Edited by T. Braun, E. Bujdos6, R. Henkel- mann, J. I. Kim, F. Lux, H. Stark and R. Zeisler. Reprinted from the Journal of Radio- analytical Chemistry. Volume I, pp.iv + 955; Volume 11, pp. iv + 1008. Budapest: Akadkmiai Kiad6. 1978. Price $175 (2 volumes).360 CONFERENCES Practice of Thin Layer Chromatography. Joseph C. Touchstone and Murrell F. Dobbins. Pp. xxiv + 383. New York, Chichester, Brisbane and Toronto: John Wiley. 1978. Price k14.05; $27.30. Neutron Diffraction. Edited by H. Dachs. Topics in Curvent Chemistvy, Volume 6.Pp. xiv + 357. Berlin, Heidelberg and New York : Springer-Verlag. 1978. Price DM65; $32.50. Advances in X-ray Analysis. Edited by Charles S. Barrett, Donald E. Leyden, John B. Newkirk and Clayton 0. Ruud. Pp. xvi + 325. New York and London: Plenum. 1978. Price $47.40. Volume 21. Mossbauer Effect Data Index Covering the 1976 Literature. Edited by John G. Stevens and Virginia E. Stevens.Pp. viii + 357. New York, Washing- ton and London: IFI/Plenum. 1978. Price $114. Antibiotics : Isolation, Separation and Puri- fication. Edited by Marvin J. Weinstein and Gerald H. Wagman. Jouvnal of Chromntogvaphy Libravy, Volunze 15. Pp. xiv + 771. Amsterdam, Oxford and h'ew York: Elsevier. 1978. Price $84.75; Dfl195. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man.Volume 16. Some Aromatic Amines and Related Nitro Compounds-Hair Dyes, Colouring Agents and Miscellaneous Indus - trial Chemicals. Pp. 400. Lyon: International Agency for Research on Cancer. Distributed by the World Health Organization. Available in the UK through HM Stationery Office. 1978. Price SWFr50; $20. IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans.Volume 17. Some N-Nitroso Compounds. 1 ~ N D MEETINGS Proc. Analyt. Div. Chem. SOC. Environmental Aspects of N-Nitroso Com- pounds. Proceedings of a Working Confer- ence held at the New England Center for Continuing Education, University of New Hampshire, Durham, New Hampshire, Edited by E. A. Walker, M. Castegnaro, L. Griciute, R. E. Lyle and W. Davis. IARC Scientific Publications No. 19. Pp. xxvi +566. Lyon : International Agency for Research on Cancer. Distributed by the World Health Organization. Available in the UK through HM Stationery Office. 1978. Price SWFr100; $25. USA, 22-24 August, 1977. Pp. 365. Lyon: International Agency for Research on Cancer. Distributed by the World Health Organization. Available in the UK through HM Stationery Office. 1978. Price SWFr50; $25.

ISSN:0306-1396    

DOI:10.1039/AD9781500359

出版商:RSC    

年代:1978

数据来源: RSC

摘要:

360 CONFERENCES AND MEETINGS Proc. AnaZyt. Div. Chem. SOC. Conferences and Meetings Microprocessors and the Chemist Janunvy 18, 1979, Havwell The Chemical Society is organising a symposium, to be held in the Cockcroft Hall of AERE. One of the aims of the symposium is to gauge the interest within the Chemical Society in the formation of a Subject Group for Micro- processors. Among the lectures given will be “Micro- processors and Analysis, ’’ by Dr.D. Betteridge, “Microprocessors and Scientific Research, ” by Dr. D. R. Deans, and “Microprocessors and Process Control,” by Dr. P. J. King. For further information concerning this symposium please contact Dr. M. D. Robinson, The Chem- ical Society, Burlington House, Piccadilly, London, W1V OBN. High-performance Liquid Chromato - graphy Seminars Januavy 15 and 16, 1979, St.Albans Spectra-Physics Ltd. announce the first in a programme of five one-day seminars on the high- performance liquid chromatography technique as applied to specific fields. The first seminar, entitled “HPLC in the Clinical and Biomedical Field,” will be held on Monday January 15, 1979, and will be repeated on Tuesday 16, starting at 10 a.m., at Spectra-Physics’ head office in St.Albans. The format will consist of a brief introduction to the techniques of liquid chromatography, followed by presentations from the following speakers on the applications of HPLC in their particular fields of work: Dr. R. Bland (Glaxo Allenburys) ; Dr. C. Jones (Wellcome ResearchDecember, 1978 CONFERENCES AND MEETINGS 36 1 Laboratories) ; Dr.M. O’Hare (Ludwig Institute of Cancer Research); Dr. P. Froehlich (Life Sciences Laboratory, Spectra-Physics, Santa Clara, California) ; Mr. M. Brown (Technical Support Laboratory, Spectra-Physics, S t . Albans) . The fee for this seminar will be L15.00 per person, to include a buffet luncheon and refresh- ments. If you would like to attend, please write direct to the Autolab Division, Spectra- Physics Ltd., 17 Brick Knoll Park, St.Albans, Herts., AL1 5UF, stating which day you would prefer to attend. Pittsburgh Conference on Analytical Chem- istry and Applied Spectroscopy March 5-9, 1979, Cleveland, Ohio, USA The 1979 conference theme is “Continued Growth in Analytical Chemistry and Applied Spectroscopy Through Expanded Communica- tion.” Fifteen technical symposia and five award presentations, in addition to the largest US domestic instrument display, will be conduc- ted at the Cleveland Convention Center.Over 500 technical presentations and 400 different exhibitors are anticipated. The technical sym- posia include : “Liquid Chromatography for Environmental Regulatory Requirements” ; ‘‘Practical Applications of Glass Capillary Columns in Gas Chromatography” ; “Problems and Solutions in Capillary Gas Chromato- graphy” ; “Applications of Ion Chromato- graphy” ; “Photoacoustic Spectroscopy” ; “Lab- oratory Systems Management” ; “Micropro- cessors in Action” ; “New Surface Techniques” ; “Trace Analysis in Characterisation of Mater- ials” ; “Environmental Analysis of Water and Sediment”; “The Use of ICAP Emission for Environmental Analysis” ; “Symposium on Biomedical Aspects” ; “New Analytical Tech- niques on the Horizon” ; “Fourier Transform - Computer Dispersive Groups” ; and “New Sur- face Analysis Instrumentation.” The awards symposia include : Spectroscopy Society of Pittsburgh Award; Society for Analytical Chemists of Pittsburgh Award ; Hasler Award; Dal Nogare Award; and Coblentz Award.For further details contact Charles J. Belle, Ferro Corporation, 7500 E. Pleasant Valley Road, Independence, Ohio 44131, USA. Analysis 79: Automation in Industrial and Clinical Chemistry July 16-18, 1979, London The next Analysis conference will be held at The City University, London, and will focus atten- tion on the cross-fertilisation of ideas and con- cepts of automation between workers in clinical, industrial and academic environments.Automation implies a system approach that can be applied at all levels of the analytical procedure ; it has, in addition to a technical and scientific impact, an influence on managerial, organisational and economic considerations. The conference will focus attention on all of these aspects in the following sessions: educa- tion ; new instrumentation ; costing and manage- ment ; applications ; and standardisation.The programme committee, consisting of Dr. Peter Stockwell, Dr. Fred Mitchell, Derrick Porter and Fred Fearn, have invited an international team of authoritative speakers to provide the keynote lectures and to chair the various sessions. Whilst the majority of speakers have been invited, there will be sessions for short, submitted papers.For further details on Analysis 79 contact Beverly Humphrey, Scientific Symposia Ltd ., 33/35 Bowling GreenLane, London, EClR ODA. VIth International Histochemistry and Cytochemistry Congress 1980 August 17-22, 1980, Brighton The Congress will be held a t the Metropole Trade and Conference Centre. The scientific programme consists of symposia, free communi- cations and poster sessions.The topics to be included are : methodology-innovation and validation ; quantification ; immunocytochem- istry ; histochemistry in pharmacology and toxi- cology ; developmental processes ; cell injury, senescence and cell death; cell uptake and transport ; histochemistry in pathology ; haema- tology ; chromasomes - chromatin ; and mineral- ised tissue.In conjunction with the Congress the Micro-80 symposium and exhibition will be held. The symposium programme is : “Scanning Electron Microscopy (Developments in Instrumentation and Applications)” ; “Microscopy of Art and Archaeology” ; “Microscopy of Polymers and Fibres” ; “Microscopy of Organic Sediments” ; Micro Diffraction” ; “Microscopy of Resins” ; and “Microscopy of Viruses.” For further de- tails of either event contact The Administrator, Royal Microscopical Society, 37/38 St.Clements, Oxford, OX4 1AJ.362 CHEMICAL SOCIETY: ANALYTICAL DIVISION Proc. AnaZyyt. Diu. Chew. 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. Brief 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 o f Water General Principles & 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.Cloth bound 196pp f 7.50 ( $1 6.50) CS Members f5.75 83’f x 6$” 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 1 17pp f 7.20 ( $1 5.75) CS Members f5.50 83” 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 to 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 8%’‘ x 5;” 0 851 86 777 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 f 7.25 ( $1 6.00) CS Members f5.50 8%“ x 5Sf’ 0 85186 787 1 THE CHEMICAL SOCIETY, Distribution Centre, Blackhorse Road, Letchworth, Herts., SG6 1 HN, England.

ISSN:0306-1396    

DOI:10.1039/AD9781500360

出版商:RSC    

年代:1978

数据来源: RSC