Document KdLXgKovL3MZ8zK64wpveJ30

ir Journal of the Association of Official Analytical Chemists Editorial Board Daniel Banes, Chairman EDITORIAL COMMITTEE William Hokwttz A. P. Mathers Peter Chichilo F. W. Quacklin'^ I. Hoffman C. O. Willits Helen L. Reynolds STAFF Da^'" ies, Editor-in-Chiej eynolds, Editor vach, Managing Editor ' ok. Assistant Editor \lAXii.Talley, Assistant Editor W. M. Hoffman, Book Review Editor VOL. 50 OCTOBER 1967 No. 5 1 CONTENTS Golden Jubilee Papers PAGE The Continuing Problem of Sampling. By F. W. Quackenbusli and R. C. Rund.. 997 The Role of Statistics in Regulatory Work. By W. J. Youden ............................ 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 llonvitz 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 ChemisLry 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. Schechter 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.* "r-hed, third floor, 414 Water Street, Baltimore, Maryland 21202 Editorial and Advertising Office: Box 540, Benjamin Franklin Station, Washington, D.C. 20044 Phore: Area Code 202 962-4809 Copyright, '00V, uy .at Association of Official Analytical Chemists, Inc. Entered as second class matter at the post office at Baltimore, Md., under the Act of August 24. 1912. Acceptance lot mailing at special rate of postage provided for in the Act of February 28, 1915, embodied in paragraph 4, section 412 F. L. A it. authorised March 2.5, 1931. Issued six times a year in February, April, June. August, October, and December. Printed in U.8.A. MON-MT-008563 1 TOWOLDMON0003237 WATER_PCB-00000259 PAGB 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 Organothiophcsphorus Pesticides and Same of Their Sulfur-Containing Breakdown Products After Thin Dryer Chroma tography. By MohamerlTawfik 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 ... i................................. 1098 Improved Method for the Determination of Ethylenebisdithioearbamate Residues in Plants, Fruits, and Vegetables. By Charles F. Gordon, Richard J. Schttckert, and William E. Bornak................................................................................ 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 Waxes Correlation of Fatty Acid Structure with Preferential Order of Urea Complex Formation. By John L. Iverson and Ii. W. Weik............................................ Ill 1 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 Z. Samish.. 1194 Instrumental Techniques Detection of Solvent by Infrared Spectrophotometry. By George Schwartzman, Daniel Sullivan, andEvelyn Samoff .......................................................... 1196 Color Additives Determination of 1 -Phenyl;;zo-2-n;tplitkoi in D&C Red No. 17. By John C. Molitor ....................................................... 1198 Determination of 4(4-Chloro-2-sulfo-5-tolylazoi-l-naphthol in D&C Red Nos. 8 and 9. By CharlesStein ....................................................................................... 1199 Mycatoxins Note on a Water-Based Afiatoxin Standard. By Robert Peterson and A. Ciegler.. 1201 Book Reviews ................................................................................................................... 1203 I '! I n MON-MT-008564 TOWOLDMON0003238 WATER_PCB-00000260 n'l'AC commission; ox mkthoijs ok rKsTtcinK mmrE AXAtvste PESTICIDE RESIDUES 10(57 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 and or< the ap pendixes presented by the members atul associate members of the Commission as indicated. J. Fumigant Residue Analysis Tltt* Commission agreed that it was desir able lo develop rapid, sensitive multidetectkm 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;oii site" u*sc 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 Commission 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 suitable. Work on sampling boxed fruit liad been completed and investigation of sampling procedures tor shiploads and other consignments was in progress. Both methods of residue analysis appeared to the Commission to be accept able. 3. Organotuercary Fungicide Residue Analysis Regulatory methods for organomcrcury 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 iikel.v to be cheaper and iust as sensitive, did not- distinguish the form in which the mercury was bound. In the United States, Use Food and Drag Administration made 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. Orga rioehiorine Pesticide Residue Analysis (a) Evaluation--by J, William Cook (Division of Food Chomhiry, Food and Drug Administration, Washington, C,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 nusaber 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, aidrin, dkldrin, heptaehlor, endriu, chlorclaae, endosulfam, and many other chemicals. There are a few hundred pesticide chemicals In xm; some of rhes* consist of mom than MON-MT-008565 TOWOLDMON0003239 WATER_PCB-00000261 10 JOV8NAL OF THE A.0.A.C. {Yol. 30, No. 5, 1067) one compound and some 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 multkleioetiou method of analysis. Whether or not the}- are significant as residues, their presence must be 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 tile 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 but some important achievements in flint 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 tip 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, e.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 the total procedure have also had to be made. The choices may not necessarily have been the best ones, but as the total procedure developed, the more difficult ib became to undertake ;my substitutions. Many of the steps add to the certainty of the identity of Urn 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 packing, liquid phase, temperature of operation, kind of detector, and operatine parameters--are all highly important when one is attempting ro 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 all of many chemicals. The collaborative study of multideteciion 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 rnitltkletectioa pro cedures. It has 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 studifes ou those methods. 11 was decided that & special referee for collaborative studies would be appointed; he would work wish the specialist in method ology for the orgauochlorines, (Monophos phates, herbicides, etc., to come up with total procedures which are ready for collaborative, study if possible, and than describe those procedures, obtain collaborators, submit samples, receive arid tabulate data, etc. It was proposed and accepted that if members of irPAC were available to participate in this collaborative effort they would ho wel comed by AOAC. It is anticipated that this program will become effective early ia 19(17. 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 thcruiioniv detector on a split stream or in tandem so that a separate but simultaneous readout for both orgauochlorines and organophosphates will be made. The simultaneous readout from the two detectors adds to the certainty of the identity of the compounds. For instance, p&rsthion gives a large re spouse on the thermionic detector due to the phosphorus and a much smaller response on the IRC detector due to the AOs group. The presence and ratio of these two peaks along with retention time are quite characteristic. Likewise, trithion gives response by bath 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 y f : 1 A 4 | fj ,1 | .;|j f| i Ia TOWOLDMON0003240 WATER_PCB-00000262 M'FAG COMMISSfOX OX iJlSTRODJ* OF PESTICIDE RBSIDl' ASAhYglS 100* * (b) Possible Interference by Chlorinated Biphenyls---hy G. Widmark (Institute of Analytical Chemistry, University a} Stockholm, Ratlugsvagen 90, Stockholm SO* Sweden) A large number of unknown but ehlorinecontainmg compounds have been detected in addition to the ordinary pesticides in tin* .'sriairsis of samples, using both the electron capture and the mierocoulamefric 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 compounds are polychlorinated biphenyls, potent intori somewhat in nature towards those of higher degree of ehloriimtiun. A large number of samples have been examined. Polychlorinated bipbemls are found especially in fell and in ,,rn birds, but also in conifer needle?! mid in some samples of human depot fat. Two hun dred samples of soil and water amt twenty samples of terrestrial mammals contained no detectable flinoimfs of chlorinated biphenyls. Typical GLC traces are given by Jensen and Widmark (i's. By vising a nitration method, most, of the ordinary pesticide can be re moved from extracts and the polychlorinated biphenyl trill be unaffected. In this way, it has been shown that two of lite major chlorinated biphenyl peaks overlap the peaks of p,p'~T)T)T and 0,p'-DDT, respec tively. This overlap is found with SF-H6 columns, most frequently used for the quan titative residue analyses reported tsi litera ture, bur. not with QF-3 columns. (c) Confirmation of Identity-- by K. E. Elgar (Shell Research jLtd., Woodstock Agriculture Research Centre, Siidngbourne, Kent, England) Multidetaction methods would seem to bo essential for the analysis of organoehlorine residues because of the number of chlorinated components which can be present in any one sample. However, there are problems of interpretation even when techniques are uml with the resolution and sensitivity of electron capture GLC. For example, the resolution of the GLC column may not be sharp enough to separate components; or impurities present in the leduiiwtl pesticide or other natural products present in the ex tract may complicate the analysis; or some insecticides may thermally or catalytieally decompose during the analysis. For these reasons, residues of organochiorine 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 in 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 Mf of pesticides in various TLC or paper chromatographic systems are highly correlated. Further more, Ri values in paper chromatography arc closely correlated with R> 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, rut Rf value from TLC or paper chromatography for a p-value), a GLC retention rimti of a derivative formed by chemical reaction, and pestieklai activity against a susceptible organism are considered to be independent parameters giving signifi cant evidence of identity. 5. Ovgamophosphorus Insecticide Residue Analysis Hie Commission concluded that while the regulatory methods were adequate for para tteen and malatMon, clarification of the terminal residue situation would be welcome in some instances. However, more work on the cleanup stage for malsthion residues in eggs, milk, and dried fruit was indicated. 6. DtchlorvosS Residue Analysis By R. A, E. Galley (Shell Research Ltd., Woodstock Agricultural Research Centre. Sittingboume, Kent, England) Five different approaches have been de veloped for the determination of traces of dielilorvos: total phosphorus (4, 5), coiorim- MON-MT-008567 TOWOLDMON0003241 WATER_PCB-00000263 1070 JOVHNAL Of TUB A.O.A.C. (Vol. 50, Xo. 5,1967) etry using dixiiirophenylhydrazine (6), alka line resorcinol {7, 8), specific bioasssj* (9), cholinesterase inhibition (10-12), and gasliquid chromatography with the thermionic detector (13) and the miemcoulometric detector (14). On the basis of sensitivity, selectivity, speed, and possibility of multidetecriori, the most suitable technique is GLC. Its sensi tivity (in the nanogTatn range with the more sensitive detectors) is approached only by the cholinesterase inhibition procedure, and it, is unmatched on the 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 decoroposition of dichlorvos on the GLC column, md the selection of the best detector from (a) electron capture, (ft) thermionic, (c) microcoulonietric, and (d) flame photometric. The other sensitive method which i* in widespread use (and which, together with GLC, offers additional evidence of identity) is the cholinesterase inhibition procedure. This is a genera! method for anticholinester ases; to analyze mixtures of inhibitors, separation before the analysis is required. However, the volatility of dichlorvos is such that it can be steam distilled front 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 the 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 are available. Dichlorvos may be quantitatively removed from air lay 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 inaterkls. 7, Pipemnyl Rmoxidc Residue Analysis The Commission recognized the need for reliable methods for residues of piperonyl butoxide and certain allied materials such as alJelhrin and AIGIv 245. 8. Ktidloavtivaliau Methods of Analysis The Commission was informed that the International Atomic Energy Agency (IAEA) had indicated that it would be prepared to (a) provide facilities for co-ordinating col laborative studies of existing radioactivation methods, (ft) assist organizations in the use of activation techniques lor 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 residue an.di-sis was hr more suitable. Bbjkrk.vces (1) Jensen and Wklraark, AtlaChem. SeamL. ia press. (2) Robinson, J., Richardscm, A., and Elgar. K. E., "Charlies! Identity in UltramicroAnatym* presented at the I82ud Mmhng of the Americas Chemical Society. Sep tember 1966, at Mew* York Ciiy. (3) Bowman, M. C-, and Berosa, M,. Vki* Journal 48, 943-152 (1965). (4) Laws, E, CJ, and Weblev. T). J,, AnalyU 36,240 -255 (I960. () Salitnan, 1*. M., Anal. Chem. 36, 113-tM (1964). () TIughes, J. T,, Arnlyxl 88, 318-319 US83). (7) Geiger, M., and Purer, R,, Z. Aim!, (them. 174, 401-407 (1800). (8) Bitchier, W., Hcisler, V., and Furor, R.. ibid. Z13, 28-80 (1965). (9) Sun, Y.-P., and Johnson, E. R., This Journal46, 524-430 (1963). (10) Giang, P. A., and Hall, S. A.. Anal. Chon. 23, 1830-1834 (1951). (11) Giang, P. A., Smith, F. P., and Hail. S. A.. /. Agr. Pood Cham. 4, 821-522 (1956). (12) Porter, P. E., "Vapona Insecticide MON-MT-008568 TOWOLDMON0003242 WATER_PCB-00000264 H 1MC COMMISSION' ON METHODS OF VBSTICIIJE HEStUCK ANALYSIS 3071 CDDVF)", in Analytical Methods for Pesticidm, Plant Growth Regulators, and Fuad Additives, Vol. II, G. Zwcig (Ed.), Academic Press, New York, 1964, pp. 561-579. <1B) El-Refai, A. R., ami Ghifirkia, Laura. This Journal 48, 374-379 (1065). CM) Boone, G. H,, ibid. 48, 748-752 (1965). (15) "Radioisotopes 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, 1966. IUPAC Commission on Terminal Residues By II. EGAN, Secretary to the Commission. (Laboratory of the Government Chemist, Corn wall House, Stamford St., London, 8.E.1, England) The first meetings of the above Commis sion of the Pesticides Section of the Applied Chemistry Division of IUPAC were held in Geneva in November 1986 under the chair manship of Dr. II. Ilnrtig. The following ac count of the proceedings is based on the minutes of the meeting and mi 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 grow]) to further this knowledge with particular re gard to the uses of carbamates in food production. (a) Evaluation--by J. William Cook (Division of Food 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-naphthoi was small and difficult to sep arate from carbaryl. Thus, if was considered that, I-naphthol need nut be measured separately front carbaryl. Tolerances for carbaryl established in the lamed States are based on the assumption that the major part of the residue is the intact carbamate. Since riic establishment of the initial toler ances for carbaryl, work hag been done which may have some bearing ou the quanti tative and qualitative aspects of the residue. Light, including artificial light and sun light, changes carbaryl. In the formulated state it slowly degrades under the influence oi ultraviolet and sunlight to give several unidentified products 0). Crosby ct d. (2) reported that ethanol or hexane solutions of some methylcarbatuate insecticides, includ ing carbaryl, gave a variety of cholinesterascmhibiting derivatives when exposed to either artificial light or sunlight. The products were separated but not identified. Abdel-Wahoh 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 photodeeomposition of carba mates have been established, the significance of these studies in relation to current and future tolerances for carbaryl must await further study. Whitehurst et al. (4), using the colori metric method of analysis sensitive to car baryl, l-naphfhol, 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 TOWOLDMON0003243 WATER_PCB-00000265