摘要:

Analyst, October, 1968, Vol. 93, $$. 691-693 691 Procedure for Semi-quantitative Confirmation of Some Organophosphorus Pesticide Residues in Plant Extracts BY P. J. WALES, C. E. MENDOZA, H. A. McLEOD AND W. P. McKINLEY (Research Laboratories, Food and Drug Directorate, Ottawa 3, Ontario, Canada) This paper describes the combination of carbon-column chromatography with thin-layer chromatographic - enzyme inhibition technique for semi- quantitative confirmation of organophosphorus pesticides. The combined procedure was evaluated for azinphos-methyl, carbophenothion, diazinon, disulfoton, malathion, mevinphos and parathion. Based on separation of compounds by elution from the column, two mixtures of standards were added to potato extracts and eluates and were analysed on thin-layer chromatograms.MCLEOD, Mendoza, Wales and McKinley1 reported a procedure for simultaneous clean-up and separation of pesticide residues in plant materials by llsing a carbon - cellulose column and three eluates. The organophosphorus pesticides were selectively eluted from this column by the first and second eluants. The eluates were analysed by gas - liquid chromatography with electron-capture detection. Our previous study showed the application of a thin-layer chromatographic - enzyme inhibition procedure to screen for organophosphorus pesticides in extracts of plant samples2 the seven organophosphorus pesticides studied were distinctly and simultaneously detected when co-chromatographed with extractives from apple, beet, carrot, lettuce or pea (aliquots equivalent to 100 to 500mg of sample).However, the identity of the pesticides detected by both methodsls2 must be confirmed. It was thought that the carbon-column procedure could be incorporated into the thin-layer chromatographic - enzyme inhibition technique for such confirmation. Elution from the carbon column would separate the pesticides into two known groups. Based on the sensitivity of the enzyme inhibition technique for each compound, appropriate aliquots of the eluates could then be chosen to detect only a certain compound or group of compounds. Our recent experiment2 also showed that, while apple, beet, carrot, lettuce and pea extracts had little or no interference, the interference from potato extracts prevented the thin-layer chromatographic resolution and identification of diazinon, parathion, malathion, azinphos-methyl and mevinphos. Thus, potato was chosen as the test sample to evaluate this combined procedure for semi-quantitative confirmation of pesticide residues and to show the applicability of this procedure to all six crops.As a continuation of the thin-layer chro- matographic - enzyme inhibition te~hnique,~ s3 this semi-quantitation aims to detect pesticide residues present in amounts near the tolerance levels. MATERIALS AND METHODS The procedure and equipment used for extraction, partition and elution of plant samples and for thin-layer chromatography, including the preparation of liver homogenate and chromogenic spray solutions, were outlined in recent papers2 93 The thin-layer chromato- graphic plates were developed in 20ml of acetone diluted with hexane to 100ml.The potato samples were extracted with acetonitrile and partitioned with hexane.l 4liquots equivalent to 10 g of plant sample were eluted, at 4 to 6 ml per minute, from the carbon - cellulose column (0-7 g of Darco G-60 and 2.2 g of Solka Floc per column) by using two eluants successively; eluant A was 175 ml of 1.5 per cent. acetonitrile in hexane and eluant B was 200 ml of chloroform. 0 SAC and the authors.692 WALES et al. : PROCEDURE FOR SEMI-QUANTITATIVE CONFIRMATION OF [Analyst, Vol. 93 The extracts and the eluates were fortified with standard mixtures at the tolerance level (this connotes the amount tolerated in some crops, not necessarily in pot at^).^ Standard mixture A (Table I) contained the compounds eluted by eluant A: disulfoton (Disyston), TABLE I CONCENTRATIONS OF PESTICIDES IN SOLUTIONS FORTIFIED WITH STANDARD MIXTURE A Disulfoton, Malathion, Mevinphos, Pg Per ml Pg Per ml rug Per ml Standard mixture A .... .. .. 2-0 80.0 2.5 Extract or eluate A (A1*) . . .. .. . . 1-00 x 40-00 x 1.25 x Extract or eluate A concentrated 1000 times (A,) 10.0 400.0 12.5 * An equivalent of 10 g of sample was contained in 200 ml of A,. malathion and mevinphos (Phosdrin). Standard mixture B (Table 11) contained the com- pounds eluted by eluant B : azinphos-methyl (Guthion), carbophenothion (Trithion), diazinon and parathion. One millilitre of standard mixture A or B was added to extracts or eluates (each equivalent to 10 g of sample). To simulate the presence of the seven pesticides in potato samples at levels indicated in Tables I and 11, the extract and the first eluate were fortified with standard mixture A and were extract A and eluate A, respectively.The extract and the second eluate were fortified with standard mixture B and were extract B and eluate B, respectively. Eluates A and B were made up to final volumes of 200 ml with hexane and chloroform, respectively. Each 10-g aliquot of crude extract was diluted to 200ml with hexane. Each extract or eluate had a corresponding unfortified control. TABLE I1 CONCENTRATIONS OF PESTICIDES IN SOLUTIONS FORTIFIED WITH STANDARD MIXTURE B Azinphos- Carbo- methyl, phenothion, Diazinon, Parathion, P.g Per ml Pg Per ml Pg Per ml Pg Per ml Standard mixture B . . .. 20.0 8.0 7.5 10.0 Extract or eluate B (B,*) . . 10.0 x lo-, 4.0 x 10-2 3.75 x 10-2 5.00 x 10+ Extract or eluate B concentrated 20 times (B,) . . .. .. 2.0 0.8 0.75 1-0 * An equivalent of 10 g of sample was contained in 200 ml of B,. Both fortified and unfortified extracts and eluates were analysed by the thin-layer chromatographic - enzyme inhibition procedure, with 5-bromo-4-chloroindoxyl acetate as substrate. Based on the lowest limits of dete~tion,~ various volumes of extracts and eluates were spotted to detect selectively a single compound or group of compounds (Tables I and 11). RESULTS Figs. 1 and 2 show chromatograms of extract A and eluate A, respectively, together with the corresponding controls and standards. White streaks were visible on the thin-layer chromatographic plates for the extract A and eluate A, and sometimes caused a distortion of the malathion spot (Fig.1, Spots 4 and 7 ) . However, the streaks did not interfere with the detection of malathion or mevinphos, even when the amounts of sample were increased to 320 (Figs. 1 and 2, Spot 4) and 2000mg (Figs. 1 and 2, Spot 7 ) . With this technique, it is possible to analyse an aliquot equivalent to only 2.7 mg of sample when it is fortified with malathion at 8 p.p.m.; malathion was the only compound detected with this aliquot size (Figs. 1 and 2, Spot 9). As expected, malathion was detected in a 320-mg sample (Figs. 1 and 2, Spot 4); both malathion and mevinphos were detected in a 2000-mg sample equivalent (Figs. 1 and 2, Spot 7 ) . Mevinphos was detected in a 320-mg sample from either extract A or eluate A (Figs.1 and 2, Spot 4). Disulfoton standard, 0*4pg, was detected but the spot produced persisted for a few minutes only (Figs. 1 and 2, Spots 1 and 6). How- ever, the same amount in a 2000-mg sample equivalent was not usually detected (Figs. l and 2, spot 7).Disulfoton - k Impurities (Malathion) Malathion - I m pu rities (Malathion) Mevinphos - )E I I I I I I I I I 1 2 3 4 5 6 7 8 9 Fig. 1. Chromatogram of fortified and control extract A of potato and corresponding standards. (Concentrations are given in Table I.) 1 , 40 p1 of pesticide standard mixture at A, concentration; 2, control extract A equivalent to 320 mg of sample; 3, 80ng of mevinphos; 4, 6.4 pl of extract A fortified with pesticide standard mixture a t A, concentration (equivalent to 320 mg of sample); 5, control extract A equivalent to 2000 mg of sample; 6, 400 ng of disulfoton; 7, 40 p1 of extract A fortified a t A, concentration (equivalent to 2000 mg of sample); 8, control extract A equivalent to 2.7 mg of sample; 9, 54 pl of extract A fortified at A, concentration (equivalent to 2.7 mg of sample) Disulfoton - Impurities (Malathion) Malathion - Impurities (Malathion) )f Mev i n phos I I I I I I I I I 1 2 3 4 5 6 7 8 9 Fig.2. Chromatogram of fortified and control eluate A of potato and corresponding standards. (Concentrations are given in Table I.) 1, 40 p1 of pesticide standard mixture a t A, concentration; 2, control eluate A equivalent to 320 mg of sample: 3, 80 ng of mevinphos; 4, 6-4 p1 of eluate A fortified with pesticide standard mixture a t A, concentration (equivalent to 320 mg of sample) ; 5, control eluate A equivalent to 2000 mg of sample; 6, 400 ng of disulfoton; 7, 40 pl of eluate A fortified a t A, concentration (equivalent to 2000 mg of sample); 8, control eluate A equivalent to 2.7 mg of sample; 9, 54 pl of eluate A fortified at A, concentration (equivalent to 2.7 mg of sample) [To face p.6921Diazinon - Carbophenothion - Parathion - I mpu rity (Carbophenoth ion) Azinphos-methyl - 1 1 1 I 2 3 Fig. 3. Chromatogram of fortified and control extract B of potato and corresponding standard. (Concentrations are given in Table 11.) 1, 10 pl of extract B fortified with pesticide standard mixture a t B, concentration (equivalent to 10 mg of sample) ; 2, 10 p1 of pesticide standard mixture a t B, concentration; 3, 10 p1 of control extract B (equivalent to 10 mg of sample) Diazinon - Carbophenothion - Parathion - Impurity (Carbophenothion) Azinphos - methyl - I l l 2 3 Fig.4. Chromatogram of fortified and control eluate B of potato and corresponding standard. (Concentrations are given in Table 11.) 1, 10 p1 of eluate B fortified with pesticide standard mixture a t B, concentration (equivalent to 10 mg of sample); 2, 10 p1 of pesticide standard mixture a t B, concentration; 3, 10 p1 of control eluate B (equivalent to 10 mg of sample) [To face p. 693October, 19681 SOME ORGANOPHOSPHORUS PESTICIDE RESIDUES IN PLANT EXTRACTS 693 Figs. 3 and 4 show chromatograms of extract B and eluate B, respectively, together with the corresponding controls and standards.Azinphos-methyl, carbophenothion, diazinon, and parathion in a sample equivalent to 10 mg gave distinct spots (Figs. 3 and 4, Spot 1). Spotting of samples equivalent to 54 and 62 mg gave no interference. An impurity in 0.05 pg of carbophenothion standard was detectable by thin-layer chromatography. DISCUSSION AND CONCLUSION Thin-layer chromatograms of potato extracts were comparable with those of eluates, indicating that elution from the carbon - cellulose column gave no appreciable reduction of the inhibition caused by components extracted from potato. In marked contrast to the streaks previously obtained for pesticides in potato extract without elution from the carbon - cellulose column,2 the spots produced by the pesticides when separated into two groups were distinct and definite (Figs. 1 and 2).Thus the spots were readily distinguished from the interference caused by the components extracted from potato (Fig. 1). In combination with the carbon-column procedure, the thin-layer chromatographic - enzyme inhibition technique was shown to be applicable to the confirmation and semi- quantitation of some pesticides in extracts of potato. Separation into two groups both confirmed the identity of the pesticides detected and enabled the separation of smaller aliquots for semi-quantitation. The separation and smaller aliquots also favoured the elimination of interference. Malathion, mevinphos, azinphos-methyl, carbophenothion, diazinon and parathion have been detected as distinct spots when present at tolerance levels in crude extracts of apples, beets, carrots, lettuce and peas (equivalent to 100 to 500 mg).2 Thus, we can assume that the confirmatory and semi-quantitative procedure developed with potato extracts can be applied to these pesticides in extracts of apples, beets, carrots, lettuce and peas. The results show that disulfoton requires further study. Acknowledgment is made to Dr. D. E. Coffin and Dr. N. P. Sen for review of the manu- script, and to Mr. H. Baird and Mr. B. Korda for the photography. REFERENCES 1. 2. , Ibid., 1968, 93, 34. 3. ---- 4. McLeod, H. A., Mendoza, C., Wales, P., and McKinley, W. P., J . Ass. 08. Analyt. Chem., 1967, 50, 1216. Mendoza, C. E., Wales, P. J., McLeod, H. A., and McKinley, W. P., Autalyst, 1968, 93, 173. “1964 Offide Coisolidation of the Food and Drugs Act and of the Food and Drug Regulations with Amendments to August 23, 1967,” issued by Department of National Health and Welfare, Queen’s Printer and Controller of Stationery, Ottawa, Canada. Received March 12th, 1968

ISSN:0003-2654    

DOI:10.1039/AN9689300691

出版商:RSC    

年代:1968

数据来源: RSC

摘要:

694 AIzalyst, October, 1968, Vol. 93, $$. 694-696 A Method for the Determination of Sterigmatocystin in Grain and Oilseeds BY L. J. VORSTER AND I. F. H. PURCHASE (National Nutrition Research Institute, Council for Scienti$c and Industrial Research, Pretoria, South Africa) A sensitive method is described for the quantitative determination of the mycotoxin sterigmatocystin by thin-layer chromatography. A sensitivity of 0.0025pg is achieved by conversion of sterigmatocystin into the mono- acetate, which fluoresces an intense light blue on thin-layer chromatoplates when viewed under ultraviolet light. STERIGMATOCYSTIN is a mycotoxin that has gained increasing significance as a food or feed contaminant during the past 5 years. Mycotoxins are at present under suspicion as carcino- gens, which may be responsible for the high incidence of liver cancer in Africa.l This possi- bility is linked with the poor storage facilities that exist in many of the affected areas and the ease with which stored grains can become contaminated by toxigenic fungi.Sterigmato- cystin, in particular, has been proved carcinogenic by Dickens, Jones and Waynforth.2 Holzapfel, Purchase, S t e p and GOUWS~ found that this toxin is produced in high yield by Aspergillus nidulans and by an undescribed strain of Bipolaris. Sterigmatocystin was first obtained by the extraction of cultures of Aspergillus versicolor by Davies, Kirkaldy and Roberts4 and Bullock, Roberts and Underwood,S who proposed the structure, I, for the compound. I R=H- Thin-layer chromatography of solutions containing sterigmatocystin reveals the presence of the toxin as a brick-red fluorescent spot when the plate is viewed under long wave ultra- violet light. The spot appears at R, 0.8 when the plate is developed in chloroform containing 2 per cent.of methanol. The fluorescence is weak and difficult to detect in an impure extract of grain; this is especially so in extracts of sorghum, which contain several red fluorescent compounds. The lower limit of visual detectability has been established to be about 0.4 pg. This method is therefore one thousand times less sensitive than when applied to the aflatoxins. The possibility of determining sterigmatocystin after converting it into a strongly fluores- cent derivative was, therefore, investigated. It was found that benzoylation and acetylation gave products exhibiting the required intense fluorescence. Acetylation was preferred because this step could be readily adapted for an assay procedure.Sterigmatocystin can be converted efficiently into a diacetate by treatment with acetic anhydride and sodium a ~ e t a t e , ~ but the procedure is slow. Acetylation with acetic anhydride and pyridine, however, is rapid. Davies, Kirkaldy and Roberts4 reported that the acetylation of sterigmatocystin with acetic anhydride and pyridine is anomalous in that a mixture of products is formed. Careful study of the reaction confirmed this, but it was found that a mono-acetate, 11," melting-point * The mono-acetate (about 10 mg) is isolated from the reaction mixture by column chromatography on formamide-impregnated cellulose powder (sample weight 1 per cent.of weight of column material). The column is packed in hexane and eluted successively with hexane containing 15, 30 and 50 per cent. of benzene in portions of 100 ml each. The final elution is carried out with 100 ml of pure benzene. The eluted fraction containing the acetate is evaporated to dryness and the acetate recrystallised from anhydrous diethyl ether. The structure of the compound was deduced from mass and nuclear magnetic resonance spectroscopic results. 0 SAC and the authors.VORSTER AND PURCHASE 695 126" C, is constantly formed in yields of about 90 per cent. if close control is maintained over the conditions under which the reaction is allowed to proceed. The main reaction product has an intense light blue fluorescence on thin-layer plates.Although the introduction of an acetylation reaction complicates the analytical procedure for mycotoxins, it forms the basis of the proposed method, as the lower limit of visual detect- ability for sterigmatocystin can be decreased to 0.0025 pg. ANALYTICAL PROCEDURE Weigh 20 g of the finely ground sample into an extraction thimble and extract for 5 hours in a Soxhlet apparatus with azeotropic chloroform - methanol (87 + 13). Alternatively, blend the sample with 100 ml of the solvent for 1 minute at high speed, decant the solvent and repeat the extraction with a fresh portion of 100ml of solvent. Filter the combined extract. Evaporate the extract obtained by either method to dryness and immediately dissolve the residue in 50 ml of 95 per cent.methanol. Transfer the solution to a separating funnel, rinse the flask with 50ml of hexane and add it to the solution. Shake the mixture well and, after separation, run off the lower layer (methanol) into the flask. Extract the hexane layer twice with 25-ml portions of 95 per cent. methanol and combine them with the methanol in the flask. Discard the hexane and pour the methanol solution into the separating funnel. Dilute the methanol to 50 per cent. with distilled water. Extract the methanol solution three times with 30-ml portions of chloroform and combine the extracts. Evaporate the solvent under reduced pressure to about 10 ml. Transfer the concentrated chloroform extract quantitatively into a glass vial (2 x 1-inch diameter), and evaporate it to dryness on a water-bath.As soon as the chloroform has evaporated dissolve the residue in 1 ml of pyridine and transfer the vial to a wax-bath or sand-bath maintained at 110" C in a fume cupboard. By pipette, introduce 1 ml of acetic anhydride into the vial and evaporate the liquid slowly (in about 20 minutes). Towards the end of the evaporation blow a stream of nitrogen gently into the vial to facilitate the evaporation of the last drops. After cooling the vial, dissolve the residue in 5 ml of chloroform and cap the vial. The solution of sterigmatocystin acetate is sensitive to daylight and should be stored in a dark cupboard. Proceed with the next step as soon as possible. The chromatography should be carried out in a darkened room.Transfer, by pipette, 1 ml of a standard solution of sterigmatocystin (20 pg per 50 ml) into a vial, evaporate the solvent and proceed with the acetylation as described. Re-dissolve the reaction product in 1 ml of chloroform. Make a trial determination of the concentration of sterigmatocystin acetate in the sample solution by spotting 1, 5 and 10 pl on an activated thin-layer plate. Develop the plate in chloroform containing 0.75 per cent. of ethanol, as stabiliser, and 2 per cent. of methanol. When viewed under an ultraviolet source such as a HPW 125 W, Type 57202 E/70, Philip's lamp (peak emission about 360 nm), the presence of sterigmatocystin is revealed by a light blue fluorescent spot at R, 0.6. From the intensity of the spots the analyst can decide on the necessary dilutions or concentrations of the solution required to reach the lower limit of visual detectability.We have determined that under the conditions in our laboratory it is 0.0025 pg. Each plate evaluator should establish the lower limit of visual detectability of the acetyl- ated standard for himself under the conditions prevailing in his laboratory. RESULTS AND DISCUSSION It was found that extraction by macerating the sample with the solvent in a Buhler blender was as effective as Soxhlet extraction. The filtration rate of the suspension from the blender may be rather slow, and this step can be substituted by centrifugation and by washing the precipitate with a little solvent. Efficiency of extraction by either method was deter- mined by extracting the extracted meal for a further 6 hours in a Soxhlet. No sterigmatocystin could be detected in the extract.A mixture of equal volumes of chloroform and methanol was as effective as the azeotrope in extracting all of the sterigmatocystin. Extracted meals were combined and fed to ducklings as 30 per cent. of their ration until they were 14 days old. Their weight gain was equal to that of the controls, thus confirming that extraction was complete.696 VORSTER AND PURCHASE The aflatoxins are, in fact, extracted by this technique if they are present in the sample. As they are more polar than sterigmatocystin acetate they barely move on a thin-layer plate eluted with chloroform containing 2 per cent. of methanol, and thus do not cause interference in the detection of sterigmatocystin acetate.Sterigmatocystin is partitioned between 95 per cent. methanol and hexane (de-fatting step) in the ratio of about 9 : 1. It is, therefore, necessary to re-extract the hexane twice with methanol. Thin-layer plates prepared from Camag Kieselgel D-5, and activated for 2 hours at 105" C, were found to resolve the acetylated extract of maize and sorghum so clearly into its com- ponents that it should be possible to evaluate the chromatograms by the densitometric method described by Pons, Robertson and Goldblatt.6 We thank Dr. C. W. Holzapfel for determining the purity and confirming the structure of a sample of acetylated sterigmatocystin. REFERENCES 1. 2. 3. 4. 5. 6. Oettl6, A. G., S. Afr. Med. J., 1965, 39, 817. Dickens, F., Jones, H. E. H., and Waynforth, H. B., Brit. J . Cancer, 1966, 20, 134. Holzapfel, C. W., Purchase, I. F. H., Steyn, P. S., and Gouws, L., S. Afr. Med. J., 1966, 40, 1100. Davies, J. E., Kirkaldy, K., and Roberts, J. C., J . Chem. SOC., 1960, 2169. Bullock, E., Roberts, J. C., and Underwood, J. G., Ibid.. 1962, 4179. Pons, W. A., Robertson, J. A., and Goldblatt, L. A., J . Amer. Oil Chem. Soc., 1966, 43, 665. Received March 12th, 1968

ISSN:0003-2654    

DOI:10.1039/AN9689300694

出版商:RSC    

年代:1968

数据来源: RSC

摘要:

AfiaZyst, October, 19681 Book Reviews 697 THE DETERMINATION OF PARTICLE SIZE. I. A CRITICAL REVIEW OF SEDIMENTATION METHODS. Prepared by the PARTICLE SIZE ANALYSIS SUB-COMMITTEE OF THE ANALYTICAL METHODS COMMITTEE. Pp. iv + 42. London: The Society for Analytical Chemistry. 1968. Price [Members) 25s. ; (Non-members) 30s. Methods and apparatus for size measurement are many and diverse, and the choice of equipment is be- wildering. In the early 1960’s the Society for Analytical Chemistry, with the help of its members, set itself the mammoth task of surveying and evaluating the methods available and, as a prelimi- nary, listed 10 basic methods covering 74 types of apparatus. The present publication covers only one of these methods, namely sedimentation. The book begins with a general description of the theory of sedimentation including the applicability of, and the departures from, Stokes’ Law.The methods of analysis are classified under the headings of Gravitational and Centrifugal and are further divided into Two-layer and Homogenous methods. A brief description of the theory of each method is given, followed by details of apparatus and a critical discussion of its merits. Xot surprisingly, apart from the Micromerograph, in which air is used as the suspending fluid, all of the methods dealt with are concerned with liquid suspensions. Pipette, Hydrometer, Diver, Photosedimentation, Sedimentation Columns, and Balances, Manometric and Decantation methods are described under Gravitational Methods. Centrifugal Sedimentation methods include the Whitby Column, the I.C.I.- Joyce Disc Centrifuge, the Sharples Super Centrifuge, the Kaye Disc and the Sinicar Analyser. Although no diagrams of apparatus are given, the written descriptions are easily followed, and for those wishing to delve further a comprehensive bibliography is appended, with over 150 references. A particularly useful table listing the practical range of sizes covered by each apparatus is given. The book is an extremely useful guide, not only to those who are already concerned with particle size analysis but also to those who are new to the subject, and succeeds admirably in condensing the knowledge and experience of many experts in the science of sizing particles. Particle size analysis is becoming increasingly important in countless applications. Hindered Settling is also covered.J. DALMON TITRATIONS IN NONAQUEOUS SOLVENTS. By WALTER HUBER. Pp. xiv + 252. New York and This book discusses the theory and practice of the titration of organic compounds in solvents other than water. I t is concerned with the application of the Bronsted - Lowry theory rather than the Lewis theory of acids and bases, as the former was worked out principally for the specific problem of acid - base reactions in solvent media not containing hydroxyl ions. This is certainly convenient as most organic “acids” and “bases” are proton donors or acceptors. Not unnaturally there is a fairly heavy emphasis on methods for locating end-points, particu- larly in potentiometric, conductimetric, amperometric, spectrophotometric and thermometric procedures.The assessment of precision of titration is particularly useful in this area of the subject. Various commercial instruments are reviewed and also indicators and indicator methods. The small section dealing with the suitability of various solvents for certain types of analysis is a valuable feature of the text, and will be particularly useful to many users of the technique. In the “Practical Section” finely detailed procedures are given for the determination of many acids and bases and for the resolution of mixtures, etc. There is an excellent selection of tabular data on pK values in many different media at the end of the book. The bibliography is extensive and there are detailed author and subject indices. This book is a welcome addition to the rather sparse literature on non-aqueous titrimetry and should prove useful to most practitioners of the subject.It is well written and produced, although somewhat expensive. London: Academic Press. 1967. Price 100s. T. S. WEST698 BOOK REVIEWS [Analyst, V O l . 93 THE CHEMISTRY OF THE RARER PLATINUM METALS (Os, Ru, IR, AND RH). By W. P. GRIFFITH. Pp. x + 491. London, New York and Sydney: Interscience Publishers, a division of John Wiley & Sons Inc. 1967. Price 120s. The chemical, physical and catalytic properties of the platinum-group metals and their compounds have never failed to attract attention, and the number of related published papers, especially over the past decade, shows a growing interest in the importance of the four members of the group covered by this book. The book is primarily devoted to the co-ordination chemistry and molecular structure of osmium, ruthenium, iridium and rhodium and is, essentially, a reference book containing a coin- prehensive and critical assessment of published information, excluding patent literature, from the discovery of these metals in the early part of the nineteenth century up to the end of 1966.The section on Analytical Chemistry takes up less than 2 pages, and this is unlikely to meet the needs of the analyst with an occasional interest in these metals, or the specialist, unless use is made of the further page of 26 well chosen references. However, the analyst in this highly specialised field, who may be involved in the multifarious problems that so often find theiI way into the analytical laboratory, could find useful information in the section Physical Measurements on Complexes of the Metals, contained in the chapter General Chemical Survey. This 5-page section deals with such subjects as Electron spin resonance spectra, Nuclear magnetic resonance spectra, the Mossbauer effect, Infrared and Raman spectra and Polarography.For a book with this coverage to serve the best possible needs, adequate supporting references are essential throughout, and in this respect the book scores full marks. These references appear in their appropriate places in the text, and at the end of the book as a collated 30-page Author Index; the book also contains the usual Subject Index, and a Formula Index. ADVANCES IN PHARMACEUTICAL SCIENCES.Edited by H. S. BEAN, A. H. BECICETT and J. E. CARLESS. Pp. x + 329. London and New York: Academic Press. 1967. Price 80s.; $14.00. This second volume, like its predecessor, contains four articles on four subjects. The method of treatment indicates that the book is intended to be of interest not only to advanced students but also to pharmacists and others in the pharmaceutical industry and in hospital practice. The articles are not solely reviews of recent advances, but contain, to a greater or lesser extent summaries of the basic knowledge of each subject and are, therefore, of interest to the non- specialist as well as to those who wish to go more deeply. The first article in Volume 2 is on Kinetics and Mechanisms in Stability of Drugs by E. 13. Garrett and gives an admirable summary of basic kinetics and relates the application of this to the deterioration of individual drugs. There are about 9 pages of references at the end of the article and such a long list of references is some what formidable, and some of them must be of doubtful value.This is not always indicated in the text. It can be easily read and understood by anybody not a specialist in this field, and although, as stated in the preface it is essentially a general article, it is none the worse for this. I t also has only 4 pages of references comparatively brief article consisting of some 40 pages only, but provides an interesting introduction to the subject. The fourth article by C. A. Johnson deals with Water Determination and it Significance in Pharmaceutical Practice.Part of this article is closely related to that by E. R Garrett, as it deals with the significance of water on the stability of pharmaceutical products Mr. Johnson’s wide experience in pharmaceutical analysis has ensured that the article contain an admirable critical survey of various methods of determining water. The two volumes together provide a useful review of the application of science to pharmacy It is obviously intended that there shall be further volumes. PHYSICAL CHEMISTRY. By FRANK T. GUCKER and RALPH L. SEIFERT. Pp. xvi + 827. London The English Universities Press Ltd. 1967. Price 70s. W. T. ELWELL Volume 2. The second article is on Particle-size Analysis by I. C. Edmundson. The third article on the Flow Properties of Powders is by Barbara S.Neumann. It is K. R. CAPPER There are now several books, all American, covering what in Britain is an honours course in physical chemistry. The subject matter does not vary widely from book to book, so here emphasis will be given to what is different in the volume under review. Quite extensive space is given to “fringe benefits’’ in the following form : mathematical intro- duction (30 pp.), problems (70 pp.), reading list and data sources (30 pp.) and, at length, indexOctober, 196CYJ BOOK REVIEWS 699 (30 pp.). Such an allocation will suit only some readers. The same holds for the lead-in to the subject matter: chapter 2 et seq. comprise 75 pages on nuclei-including Mossbauer, but not (yet) n.m.r., spectroscopy-and radioactivity. One has, therefore, reached page 100 before the whole atom is broached.To persist with this “quantitative analysis,” atomic and molecular structure and spectroscopy occupy about 100 pages, gaseous behaviour 50, thermodynamics and chemical equilibria 90, solids 40, liquids 35, statistical mechanics 50, non-electrolyte solutions 40, electrolytes, electro- chemistry and ionic equilibria 150, surfaces 35, kinetics 55 and heterogeneous equilibria 45 pages. Wave mechanics is presented with a reasonable balance between description and mathematics. Although the bonding in diatomics up to 0, is dealt with adequately, that in transition metal complexes is but briefly maltreated. Useful descriptions of n.m.r. and Mossbauer spectroscopy contrast with a rather brief outline of molecular spectroscopy.The chapters on the gaseous state end with an unusual (inter alia) equation of state: it is uscful to be reminded tkiat these are still being generated at an appreciable rate. Thermodynamics includes the usual, necessarily specious, derivation of the second law from the first. Solid and liquid structures come out well, and the statistical mechanics is painless. The remaining sections seemed eminently readable when dipped into. The major criticism called for arises in connection with kinetics. I t is a symptom of injudicious emphasis that the new, widely applicable, rapid- reaction techniques are not mentioned at all, in sharp contrast with the several pages given, for example, to Mossbauer spectroscopy. The presentation generally manages to be both discursive and comprehensive.Over-simpli- fication is no worse here than elsewhere. Sometimes, however, ten lines are taken to express two lines’ worth of information. More space could have been given to simple derivations (instead of mere quotation) of exprcssions yielding, for example, dipole moments, magnetic or electric, froin bulk measurements; here the mathematics can be both elegant and simple and worth many paragraphs of wordage. Extensive references to monographs and sometimes papers are not always helpful; that to Fuoss and Kraus (1957) on conductance theory scarcely leads directly on from the given text, nor does it give Fuoss’s present views. Nearly all scientists quoted are referred to com- plete with Christian name, a very matey convention, but Debye suffers as Peter J.W. on pages 341 and 517, Peter B. J. on page 325 and Peter J. B. on page 359. Units, dimensions and symbols are not happily treated, departing far from current recom- mendations (Nature, 1967, 1272, and 1968, 308). The statement “fugacity is usually expressed in atmospheres” (p. 395) is intended to mean that fugacity has the dimensions of pressure. In conclusion, some readers may like the discursiveness and absence of heavy going often achieved by commendable verbal clarity ; others, perhaps among them analysts using isotopes, may be attracted by the introductory emphasis on nuclear properties; but others will be put off by other aspects mentioned above. The page appearance is pleasing and no typographical errors were noted. D. R. ROSSEINSKY FOUNUATIONS OF COLLEGE CHEMISTRY.By MORRIS HEIN. Pp. xviii + 395. Belmont, California: Providing an introductory course for the student with no previous experience in chemistry, this book is a good example of an American elementary text, and well worth closer study. It is attractively produced, and the claims on the dust jacket seem substantially (though not perhaps entirely) correct. There are numerous illustrations, problems and review questions organised systematically. The need to simplify has made some of the aspects seem more clear-cut than they really are, but the book moves from the elementary to the sophisticated rapidly, with a transition that is smooth and not abrupt. While few students here are in the same position as those in the U.S.A., for whom the book was written, the book will undoubtedly be a useful addition to the reference library in the sixth form, and to libraries in technical colleges and colleges of education, where what should be familiar can be approached in a fresh and intellectually satisfying way.Another possible outlet lies in the science content of liberal studies for non-specialists. The chapters on Atomic Theory and Structure, the Formation of Compounds from Atoms, and the Periodic Arrangement of the Elements are commended. Electronic configurations are dealt with at the level of the average Advanced Level student: s, p , d, f orbitals are mentioned put s and p only are given pictorially. Elementary diagrams of atomic structures and the changes in electronic configuration on bond formation are particularly clear. Electronegativitics and Dickenson Publishing Company Inc.1967. Price 74s. 6d. The development is concisely and coherently argued.700 BOOK REVIEWS [Analyst, Vol. 83 unequal sharing of electrons are mentioned, but bonds are presented as distinct types without the merging of one into the other. Certain examples among those chosen to illustrate the ionic bond can be criticised for reasons that are self-apparent: NaCl, MgCl,, NaF, LiCl, AlCl,, MgO, Na,S. Use of co-ordinate covalent bonding in sulphurous and sulphuric acids is neat and fits octet theory, but does not quite tally with bond lengths as measured. As5+ and Sb5+ and other highly polar and suspect ions are quoted. Oxidation number and nomenclature are clearly expounded, but HgNO,, instead of Hg,(NO,),, is used for mercury(1) nitrate, and Al(HCO,),, aluminium bicarbonate, ivhich may possibly exist but the reviewer has not met it, is quoted as an example of a salt with more than one positive ion.NH,HS, KHC,O,, etc., also appear in this table, which suggests that the caption needs modifying. Hydrogen bonding is soon introduced into the study of water, which proceeds to consideraffon of the physical properties of liquids and solutions, molarity and normality. Bronsted - Lowry and Lewis theories are brought into the chapter on ionisation, with the elementary chemistry of acids, bases and salts leading to the study of electrolytes, pH and electrolysis. Arrhenius is twice mis- spelt in the index but is correct in the text. Ion - electron equations and oxidation numbers feature fully in Oxidation and Reduction.The essentials of radioactivity and atomic energy are explained lucidly at the introductory level but, in a book with few misprints (about lo), argon is given as A in a transmutation equation. No mention of the terms homogeneous and heterogeneous is made in this part of the book and it is simply not true to say Examples of gases and solutions are used to introduce Chemical Equilibrium. “In the rcaction, CaCO, (g) + CaO (s) + CO, (g) an increase in pressure will slow down the forward reaction. , . .” No units are quoted for equilibrium constants and solubility products. In the survey of carbon and its compounds, including organic chemistry, 1. U.P.A.C. nonien- clature appears, and there are photographs of ball-and-stick and scale models of molecules.Aliphatic and aromatic hydrocarbons are described in modest terms and there is a glimpse of the range of other organic compounds. The other chapter at the end deals with the descriptive chemistry of selected elements, namely the alkali metals, halogens, the sulphur and nitrogen families. These two chapters comprise 72 pages but the treatment is about right in an introductory text and should generate interest in the subject. Topics (e.g., Quantum Thcory) and elements and/or their compounds (e.g., aluminium) mentioned briefly in the text are excluded from thc index, which otherwise seems perfectly adequate. I welcome the addition of this type of book to reference libraries provided for students at advanced level.While, in my opinion, this book has the blemishes indicated above, the general impression is that it is lively, well put together and the work of an experienced teacher. Accord- ingly, i t is recommended. B. J. MOODY PRACTICAL CHEMISTRY. AN INTEGRATED COUKSE. By J . W. BUTTLE, B.Sc., A.R.I.C., and D. J . DANIELS, B.Sc., Ph.D., Dip.Ed., F.R.I.C. Second Edition. Pp. xvi + 315. London: Butterworths. 1967. Price 28s. This attractively presented book, which aims at providing a continuous course of practical Chemistry, suitable for Sixth Form and Ordinary National Certificate Students, first appeared in 1962 and is well worth close study. There are three sections : inorganic and physical, organic and physical (probably to be studicd in parallel) and qualitative analysis of simple inorganic and organic compounds. Nine appendices include examination questions, details of chemicals and apparatus required, first-aid notes and various tables. The new edition adds an introductory chapter on the experimeiital basis for the present view of the atom, some new examination questions, an extension of suggestions for further work and of modern nomenclature in the inorganic section. Each experiment or preparation, for which instructions are clearly and concisely given, is followed by several short questions, some experimental, others theoretical in nature. Diagrams are clesrly drawn and labelled. Those for preparations show proprietary glass-jointed apparatus on the small scale. Structural bond diagrams are shown for organic and inorganic compounds. Dative bonds are shown in 0x0-salts, which is a matter of opinion. The treatment is compre- hensive and reliable. The book is recommended for its purpose. B. J.MOODY

ISSN:0003-2654    

DOI:10.1039/AN9689300697

出版商:RSC    

年代:1968

数据来源: RSC