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Journal of the Association of Official Analytical Chemists Editorial Board Daniel Banes, Chairman EDITORIAL COMMITTEE William Hokwitz A. F. Mathers Petes Chichilo F. W. Quacken*"' I. Hoffman C. O. Willits Helen L. Reynolds STAFF Da^,t_ jes, Editor-in-Chiej eynolds, Editor - vach, Managing Editor ;; . ok. Assistant Editor Marin Talley, Assistant Editor W. M. Hoffman, Book Review Editor Vol. 50 OCTOBER 1967 No. 5 CONTENTS Golden Jubilee Papers PAGE The Continuing Problem of Sampling. By F. W. Quackenbusli and R. C. Rund.. 997 The Roie of Statistics in Regulatory Work. By W. J. Youdon ............................. 1007 Analytical Methods and the Preclearance Food Protection Amendments to the FD&C Act. By L. L. Ramsey ............................................................................ 1013 Magic Words--Automated Methods of Analysis. By H. P. Eiduson and W. M. Hoffman .............................................................................................................. 1021 Developments in Adulteration of Food and Its Detection. By William llorvritz and Helen L. Reynolds .......................................................................................... 1024 Drug Adulterations--Past, Present, and Future. By Daniel Banes...................... 1032 Advanced Instrumentation in Forensic Examinations. By M. J. Pro and C. M. Hoffman ................................................................................................................... 1041 Is Chemistry' Going Out of Analytical Chemistry? By Clifton E. Meloan.......... 1044 The Impact of Instrumentation Upon the Teaching of Analytical Chemistry. By Stanley Bruckenstein ...................................................................................... 1046 Screening Methods in Regulatory Analyses. By R. E. Duggan ...................... 1052 Comments on Screening and Analysis of Multiple Pesticide Residues. By Milton S. Schecbter and Melvin E. Getz ....................................................................... 1056 Journal of the AOAC--The First 50 Volumes. By Helen L. Reynolds.................. 1062 published bimonthly by THE ASSOCIATION OF OFFTCIAL ANALYTICAL CHEMISTS, INC. Printed and pi.' "shed, third floor, 414 Water Street, Baltimore, Maryland 21202 Editorial and Advertising Office: Box 540, Benjamin Franklin Station, Washington, D.C. 20044 rhore: Area Code 202 962-4809 Copyright, 'HOI', '-y .no Association of Official Analytical Chemists, Inc. Entered as second class matter at the post office at Baltimore, Md., under the Act ef August 24, 1912. Acceptance Tot ihaiUng at special rate of postage provided for in the Act of February 2S, 1915, embodied ia paragraph 4, section 412 P. L. & .1. authorised March 25, 1931. Issued six times & year in February, April, June, August, October, and December. Printed in U.S.A. mmdUf1 MON-MT-008563 TOWOLDMONOOQ3237 Pesticide Residues IUPAC Commission on the Development, Improvement, and Standardization of Methods of Pesticide Residue Analysis. By H. Egan, Secretary to the Commission ................................................................................................ 1067 IUPAC Commission on Terminal Residues. By H. Egan, Secretary to the Commission .............................................................................. 1071 Direct Fluorescent Detection of Organothiophosphorus Pesticides and Some of Their Sulfur-Containing Breakdown Products After Thin Dryer Chroma tography. By Mohamed Tawfik H. Ragab......................................................... 1088 Determination of 2,4-D and Its Butoxyethanol Ester in Oysters by Gas Chro matography. By J. 11. Duffy and Patricia Shelfoon ......................................... 1098 Improved Method for the Determination of Ethylenebisdithiocarbamate Residues in Plants, Emits, and Vegetables. By Charles F. Gordon, Richard J. Schuck- ert, and William E. Bomak........................... 1102 Persistence of Scvin Residues on Some Vegetable Crops After Various Harvest Times. By Makarem Ahmed Elessawi and Abdel Rahman El-Refai.............. 1109 Oils, Fats, and {Faxes Correlation of Fatty Acid Structure with Preferential Order of Urea Complex Formation. By John L. Iverson and R. W. Weik.............................................. ilil Programmed Temperature Gas Chromatographic Technique for Detecting Trace Amounts of Fatty Acids. By John L. Iverson ................................................... 1118 Preservatives and Artificial Sweeteners Rapid Determination of Sorbic Acid in Orange Juice. By Kermit M. Floyd___ 1123 Preservatives: A Review of Methods of Analysis. By Pieter L. Schuller and Eduard Veen ............................................................................................................ 1127 Entomology Fly Identification by the Morphology of the Head and Head Appendages. By N. Aubrey Carson and Edmund F. Martinez......................................................... 1146 Fruits and Fruit Products Determination of Bitterness of Olives. By S. Cohen, A. Lifshitz, and 2. Saniish.. 1194 Instrumental Techniques Detection of Solvent by Infrared Spectrophotometry. By George Schwartzman, Daniel Sullivan, andEvelyn Samoff ..................................................................... 1196 Color Additives Determination of l-Phenylazo-2-naphthol in D&C Red No. 17. By John C. Molitor ......................................................... 1198 Determination of 4(4-Chloro-2-sulfo-5-tolylazo'i-l-naphthol in D&C Red Nos. 8 and 9. By CharlesStein .......................................................................................... 1199 Mycatoxins Note on a Water-Based Aflatoxin Standard. By Robert Peterson and A. Ciegler.. 1201 Book Reviews ...................................................................................................................... 1203 ii MON-MT-008564 il'l'AC COMMISSION' ON METHODS OK I'KSTTCinE UKSmrB AVAIA'SfS PESTICIDE RESIDUES 1067 lUPAC Commission on the Development, Improvement, and Standardization of Methods of Pesticide Residue Analysis By H. EGAN, Secretary to the Commission (Laboratory of the Government Chemist, Corn' wall House, Stamford St., Tendon, S.B.I, England) The first meetings of the above Commis sion of the Pesticides Section of the Applied Chemistry Division of HJPAC were held in Geneva in November I960 under the chair manship of Dr. R. A. E. Galley. The follow ing account of the proceedings is based on the minutes of the meeting fine! on the ap pendixes presented by the members and associate members of the Commission as indicated. 1. Fumigant Residue Analysis The Commission agreed that it was desir able to develop rapid, sensitive multidetectxm systems of analysis for residues of fumigants such as methyl bromide, ethylene dibromide, ethylene diehloride, ethylene oxide, acrylonitrile, carbon tetrachloride, carbon disulfide, and phosphine. A study of the application of gas-liquid chromato graphic methods was thought to be. worth while. A need for simple and reliable i;on site" test equipment was also discussed and attention was drawn to limitations in the use of commercial indicator tubes for measurement of residues in treated produce. 2. Diphenyl Residue Analysis The Ckmuni&ion discussed progress in the study of methods of sampling and analysts of citrus fruit for residues of diphenyl, A preliminary report of the Netherlands Cen tral Institute for Nutrition and Food Re search T.N.O. indicated that, of the two methods studied, the gas chromatographic method was the faster and more accurate; however, the thin layer chromatographic method followed by ultraviolet spectro photometry was also suit-able. Work on sampling boxed fruit had been completed and investigation of sampling procedures for shiploads and other consignments was in progress. Both methods of residue analysis appeared to the Commission to be accept able. 3. Organomereury Fungicide Residue Analysis Regulatory methods for orgommemtry residue, analysis were discussed; it was in dicated that while radioactivation facilities for this were adequate in Scandinavia, gasliquid chromatography offered considerable promise both for high sensitivity and high specificity. The neutron activation methods were probably the best where facilities were available but, like the newer cold vapor atomic absorption techniques which were likelv to be cheaper and just as sensitive, clkl not distinguish the form in which the mercury was bound. In the United States, tite Food and Drag Administration naadc a direct comparison between cold vapor atomic absorption and neutron activation tech niques; the Association of Official Analytical Chemists had recently appointed a new referee for mercury residue analysis. 4. Grga notliiorine Pesticide Residue Analysis (a) Evaluation--by J. William Cook (Division of Food Chemistry, Food and Drug Administration, Washington, D.C. 20204) Much progress has been made in the de velopment .and refinement of methods of analysis by which any or all of a large num ber of pesticide residue chemicals can be detected and measured in one general opera tion. They have come to be known as ''multidctectton" methods of analysis. The following discussion includes DDT, y-BHC, aidr'm, dieldtin, heptaehlor, endrm, ehlortlane, endosulfan, and many other chemicals. There are a few hundred pesticide chemicals in use; some of These consist of more than MON-MT-008565 TOWOLDMONOOQ3239 1Q<>8 journal or the A.O.A.C. {Yol. SO, Ko. 5,196?) one compound and arnne convert to & series of alteration products which may appear in residue analysis. Therefore, there is a large number of chemicals which can show up in a multkkucetiou method of analysis. Whether or not they are significant as residues, their presence must lx*, recognised in order nor to confuse them with significant, pesticide chemi cals. Ideally, a general method of analysis which would measure and identify all of the significant residues in all food products with a minimum of analytical effort and time would be desirable. This is not possible at the present time bat some important achievements in that direction have been obtained to date. The developments so far have made if possible to extract, clean up, measure quan titatively, and give a high degree of certainty to the identity of the compounds for up to 100 pesticide residue chemicals obtained from a great variety of food crops and products alt in one general operation. This has been done with either extracts from individual products or composites of a large number of products, c.g., ''Total diet" or ' market flasket" samples. The development of such procedures has required a tremendous Amount of effort. At each point along the way choices had to be made. As a conse quence of these choices, adjustments in tire total provedure have also had to he made. The chokes may not necessarily haw* been the best ones, but as iho total procedure developed, the more difficult it became to undertake any substitutions. Many of the steps add to the certainty of the identity of the chemicals as well as to the quantitative measurement. The extraction and the clean up procedures must yield quantitative recov eries of the chemicals. The gas chromato graphic systems--that is, combinations of column picking, liquid phase, tempera sure of operation, kind of detector, and operating parameter---are all highly important when one is attempting to obtain quantitative response from a number of chemicals. Condi tions which may be satisfactory for quanti tative results on an individual chemical or a small number of chemicals may not yield adequate quantitation for alt of many chemicals. The collaborative study of multidetection methods is not as straightforward as for "wet" methods of analysis. The relatively simple procedure that has been used by AOAC and other groups for design and execution of collaborative studies is generally not applicable to these tnnltidetec l ion pro cedures. It h.ig been the experience of FDA and some other groups that if the details of the procedure arc not described exactly and if they are not followed closely, great variations in the analytical results are ob tained. At the last AOAC meeting, a special conference was held to discuss the problem involved in collaborative studies on those methods. It was decided that & special referee for collaborative studies would be appointed: he would work with the specialist in method ology for the orgatiochlorines, monophos phates, herbicides, etc., to some up with total procedures which are ready for collaborative study if possible, and than, describe those procedures, obtain collaborators, submit samples, receive and tabulate data, etc. It was proposed and accepted that if members of TbPACI were available to participate in this collaborative effort they would bo wel comed by AOAC. It is anticipated that this program will become effective early in 1967. It will probably include extraction, cleanup, thin layer chromatography, and gas chro matography. Gas chromatography will involve the use of an electron capture detector and a ther mionic detector on a split stream or in tan dem so that a separate but sinniltaneous readout for both orpimehlorines and organophosphates will be made. The simultaneous readout from the two detectors adds to the certainty of tire identity of the compounds. For instance, p&rathion gives a. large re sponse on the thermionic detector due to the phosphorus and a. much smaller response on the EC detector due to the NO* group. The presence and ratio of these two peaks along with retention time are quite characteristic. Likewise, uithion gives response by both detectors because of the phosphorus and the chlorine in the molecule. Again, the retention time and ratio of the two responses enhance identification of the compounds being analyzed. MON-MT-008566 TOWOLDMONOOQ3240 MTAG COMMISSION OS' METHODS OF PESTICIDE RESIDUE ANALYSIS 1009 (b) Passible Interference by Chlorinated Biphenyls--~by G. Widmnrk (Institute of Analytical Chemistry, University of Stockholm, Rotlagsvagen 9b, Stockholm SO, Sweden) A large number of unknown but chlorinecontaining compounds have been detected in addition to the ordinary pesticides in the analysis of samples, using both the electron capture and the microcoulometric detector. Mass spectra of some of these compounds obtained with a combined gas chromato graph-mass spectrometer (LKB-9000) indi cated that most of the unknown cornpounds are polychlorinated biphenyls, potentiated someivhat in nature towards those of higher degree of ehlorimttitm. A large number of samples have been examined. Polychlorinated biphenyls are found especially in fish anti in sea birds, but also in conifer needles mid in some samples of human depot tat. Two hun dred samples of soil and water and twenty .samples of terrestrial mammals coitf.lined no detectable amounts of chlorinated biphenyls. Typical GLC traces are given by Jensen and Widmnrk (1). By using n nitration method, most of the ordinary pesticides can be re moved from extracts and the polychlorinated biphenyl will be unaffected. In this way, it has been shown that two of tin* major chlorinated biphenyl peaks overlap the peaks of p.p'-DDT and tf,p'-DDT, respecliveiy. This overlap is found with SF-flfi columns, most frequently used for rite quan titative residue analyses reported ia litera ture, bur. not with QF-J columns. (c) Confirmation of Identity-- by K. E. Elgar (Shell Research ltd,, Woodstock Agriculture Research Centre, Siufngbourne, Kent, England) Muitidctection methods would seem to be essential for the analysis of organochlorinc residues because of the number of chlorinated components which can be present in any otic; sample. However, there are problems of interpretation even when techniques are used with the resolution and sensitivity of electron capture GLC. For example, the resolution of the GLC column may not be dirtrjt enough w separate components; or inipurities present in the technical pcs;icicle or other natural products present in the ex tract may complicate the analysis; or some insecticides may thermally or catalytically decompose during the analysis. For these reasons, residues of organochbrine compounds should be confirmed by other analytical methods. If enough material can be isolated, infrared spectroscopy or mass spectroscopy can give powerful evidence of identity. However, with other methods its common use the physical basis underlying separation is very similar. Robinson et al, (2) reported a highly significant con cordance between the "p-values" for pesti cides in the various partition systems described by Beroza and Bowman (3). Similarly, retention times on different GLC stationary phases and Rf of pesticides in various TLC or paper chromatographic systems are highly correlated. Further more, Ri values in paper chromatography arc closely correlated with Rt values in TLC and with p-values. It is possible to do a great deal of work with the in tention of establishing the identity of a compound, but very little additional evidence will be gained because the results from the methods used were not independent. GLC retention time, an Rf value from TLC or paper chromatography (or a p-value), a GLC retention rime of a derivative formed by chemical reaction, and pesticidai activity against a susceptible organism are considered to be independent parameters giving signifi cant evidence of identity. 5. Orgimophosphonis Insecticide Residue Analysis The Commission concluded that while the regulatory methods were adequate for parathion and malathion, clarification of the terminal residue situation would be welcome in gome instances. However, more work on the cleanup stage for malathion residues in eggs, milk, and dried fruit was indicated. 6, Dichlon-os Residue Analysis By R. A. E. Galley (Shell Research Ltd., Woodstock Agricultural Research Centre. Sittingboumu, Kent, England) Five different approaches have been de veloped for rite determination of traces of diclilorvos: total phosphorus (4, 5), colorim- MON-MT-008567 TOWOLDMONOOQ3241 1070 JOfHNAt, or THE A.0.A.C. (Vol. 50, No. 5, 1067) etry using diiiilrophenylhydrazine (6), alka line resorcinol (7, 81, specific bioasssr (9), cholinesterase inhibition (10-12), and gasliquid chromatography with the thermionic detector (13) and the microcouiometric detector (14). On the basis of sensitivity, selectivity, speed, and possibility of multidetmior,, the most suitable technique is GLC. Its sensi tivity (in the nanogram range with the more sensitive detectors) is approached only by the cholinesterase inhibition procedure, and it. is unmatched on rhe other counts. How ever, there are two aspects in the analysis of traces of dichlorvos by GLC in which improvements are needed. These are the sup pression of decomposition of dichlorvos on the GLC column, mi ifio selection of the best, detector from {a) electron capture, (b) thermionic, (c) mieroeosslttmetric, and (d) flame photometric. The other sensitive method which is in widespread use (and which, together with GLC, offers additional evidence of identity) is the cholinesterase inhibition procedure. This IS (I. general method for anticholinester ases; to analyze mixtures of inhibitors, separation before the analysis is required. However, rhe volatility of dichlorvos is such that it can he steam distilled from ex tracts even when they contain a high pro portion of fatty material. It is possible, there fore, to obtain a degree of specificity in rhe analysis for dichlorvos by cholinesterase in hibition by incorporating a steam distillation step before the determination. Procedures for the collection of dichlorvos vapor from the air, extraction of residues from crops and tissues, and cleanup arc available. Dichlorvos may be quantitatively removed from air by bubbling through dis tilled water. Chloroform, methylene chloride, and benzene have been used to extract di chlorvos residues. Partitioning from an organic, solvent into water, column chroma tography on silica gel, and steam distillation provide adequate cleanup from fatty and noufarty materials. 7, Plperonyl Rutoxide Re*ithie Analyi< The Commission recognized the need for reliable methods for resit!ties of pipcronyl butoxide and certain allied materials such as ahelhrin and MGK 245. 8. Kadioactivallon Methods of Analysis The Commission was informed that the International Atomic Energy Agency (IAEA) had indicated that- it would be prepared to () provide facilities for co-ordinating col laborative studies of existing radbaenvafion methods, (b) assist organizations in the use of activation techniques for the evaluation of analytical methods in general, and (c) help laboratories wishing to establish radio chemical techniques (15). It was agreed that while radiochemical methods of analysis were useful for mercury and for bromine residue determinations, they were very ex pensive and not necessarily more sensitive or more specific than some other methods. Moreover, although they were often useful in metabolic or field residue trial studies, radiochemical methods were in general in appropriate to regulatory methods of analy sis * the development of various other methods of regulatory marine analysis was hr more suitable. Rbissh.vcbs (1) Jensen and Wklraark, /fe- C-he.m. SmtuL. in press. (2) Robinson, J., RkimrcUcm, A., and Elgar. K. F., "Chemical Identity in tJltramkvoAnatym* presented at the 152nd Meeting of the American Chemical Society. .Sep tember 1986, at Xew York City. (3) Bowman. M, C., and Beroza, M.. This Journal 48, 943-952 (1965). (4) Laws, B, Q,, and Webtey. D. J,, Analyst 86,240-255 (1961). (5) Saliman, 1*. M., Amt. Chcm. 36, 113-114 (1964). () Hughes, J. T,, Analyst 88, 318-319 (1063). (7) Geiger, M., and Furor, JL Z. - Anal, (them. 174, 401-107 (I960). (8) BiicIUer. W., Hcizler, W., and Furor, R.. ibid. 213, 28-30 (1985). (9) Sun, Y.-P., and Johnson, E. R., This Journal 46, 524-530 (1963). (10) Oiang, P. A., and Hall, S. A.. Anal. ('hem. 23, 1830-1834 (1951). (11) Giang, P. A., Smith, F, i*\, awl Hall. S. A.. /. Ayr. Pond Chern. 4, 621-822 (1956). (12) Porter, P. R, "Vapona Insecticide MON-MT-008568 TOWOLDMONOOQ3242 IS P.IC COMMISSION' ON METHODS OF VISSTICUJE ttg*U>l'K ANALYSIS 1071 (DDVP)", in Analytical Methods jar Pesticides, Plant Growth Regulators, and Food Additives, Vol. II, G. Zwcig (Ed.), Academic Press, New York, 1964, pp. 561-579. < 13) El-Refai, A. R., and Giuffrida, Laura. This Journal 48, 374-379 (1965). CM) Boone, G. H., ibid. 48, 748-752 (1965). (15) "Radioin-otopes in the Detection of Pesti cide Residues", proceedings of the Panel on the Uses of Radioisotopes in the Detection of Pesticide Residues, Inter national Atomic Energy Agency, Vienna, April 12-15, 1906. IUPAC Commission on Terminal Residues By II. EGAN, Secretary to the Commmien. (Laboratory of the Government Chemist, Corn wall House, Stamford Si., London, S.E.l, England) The first meetings of the above Commis sion of the Pesticides Section of the Applied Chemistry Division of IUPAC were held iu Geneva in November 1986 under die chair manship of Dr. II. Ilurtig. The following ac count of the proceedings is based on the minutes of the meeting and on the ap pendixes drawn up by members and associate members of the Commission as indicated. i. Terminal Carbamate Residue The commission discussed the present position regarding knowledge of the nature of the, terminal residues of carbamates, in cluding carbaryl, as indicated in the evalua tions below, and set up a working group to Further this knowledge with particular re gard to the uses of carbamates in food production. (a) Evaluation--by J. William Cook (Division of Fowl Chemistry, Food and Drug Administration, Washington, D.C. 20204) In the earlier studies on carbaryl residues, both carbaryl and its hydrolytic product, I-naphthol, were considered. Residue studies on many crops showed that the quantity of 1-mphthol was small and difficult to sep arate from carbaryl. Thus, it was considered that, 1-naphthol need nut be measured separately from carbaryl. Tolerances for carbaryl established in the United States are based on the assumption that the major part of the residue is the intact carbamate. Since r,hc establishment of the initial toler ances for carbaryl, work has been done which may have some bearing ou the quanti tative and qualitative aspects of the residue. Light, including artificial light ami sun light, changes carbaryl. In the formulated state it slowly degrades under the influence of ultraviolet and sunlight to give several unidentified products (1). Crosby ct al. (2) reported that ethanol or hexane solutions of some methykarbatoate insecticides, includ ing carbaryl, gave a variety of cholinesteraseinhibiting derivatives when exposed to either artificial light or sunlight. The products were separated but not identified. Abdel-Wahcb and coworkers reported that, the nature of the surface, the light, and the compound affected the rate of conversion of carbaryl and other carbamates in vitro in the solid state. Since neither the qualitative nor quantita tive aspects of photodeeamposinon of carba mates have been established, the significance ot these studies in relation to current and future tolerances for carbaryl must await further study. Whitehurst- ct al. (4), using the colori metric method of analysis sensitive to car baryl, 1-naphthol, and 1-naphthol conjugates, concluded that when cows were fed & diet containing carbaryl, no residues, to the limit of the method, were found in milk. This was MON-MT-008569 TOWOLDMONOOQ3243