Document 2RnQMdyqvkNEkd01R6XyXvwb7

.*A V ntpAC fOMMiRKifix ox MinnooR or l-Ksncmr: iikmdiik analysis ... ........ PESTICIDE RESIDUES _ 1007 IDI'AC CoinmiKKion on the Development, Improvement and Slniidar<!i/.nljoii of Me.lliods of Pesticide Residue Analysis Jly 11. KG AN, Secretary to lhe Commission (buboratory of the Government Chemist, Com- wnll 11 Stamford Sl.t Iximlon, S.E.l, England) The find. imTlingi. of the above Commisninn of tile I'rslicide.s Secl-iim of the AJ>|iliecl ('lieinislry Division of HJJ'AC were held in Grncvn in November 1900 tinder the chair manship of Dr. li. A. K. G.'illey. 'J'he followiiiC account. of Uir proceedings is Imsed on the minutes of the meeting nod on the ap pendixes prescrib'd l>y the. members nntl HKSorinte members of the Commission ns imlicnled. . 1. I'niniioilil KccmImc Annlyntn Tin: ColiiniiKsion agreed llml. it tvns deisirnhie to develop rapid, sensitive multidctec (inn systems of nn.-ilysis for residues of j fiinnpnnls tmeli ns methyl bromide, ethylene dihroinidr, ethylene diehloride, ethylene oxide, acrylonitrile, carbon tctrneldoride, rmbon disulfide, nud plmspliinc. A study of the application of gas-liquid chrmnntogrnphio methods wns thought to Is-, worth while. A need for simple nnd relinhle "on ; site" test equipment wns also discusser) nnd ntleiiliou wns dnitvii to limilntinns in the use of roiimiereinl indicator tubes for me.'isorement of residueR in (.rented produce. 2* Diphenyl IlcMtlttr Analysi* l. The Commission discussed progress in Lite ' study of methods of sampling nnd nnnlysis of citrus fruit, for residues of diphenyl. A preliminary report ofThu Netherlands Cen tral Institute for Nutrition nud Food Jtc search T.N.O. indicated thnt, of Uie two inrlliods studied, the gns chromatographic melliod wns the fester nud more ne.rurnte; however, the thin Inver chromnlogrnpliic method followed by ultraviolet spcr.irn, photometry wns also suitable. Work on , sampling boxed fruit had been eomplr.lcd nud investigation of sampling procedures for shiploads nnd other consignments wns in progress, both methods of residue nunlysis appeared to the Commission to be Accept able. 3. Orgunomcrcury Kunpicidr llr-sidur. Anaiyaia Hcgulatory methods for orgntiomcrcury residue analysis were discussed; it wnn in dicated thnt while radioaclivation facilities for this were adequate in Scandinavia, gasliquid chromatography offered considerable promise, both for high sensitivity and high sjKcifuity. Tlic neutron activation methods were probably the l>est where fiicilitics were nvnilnblc but, like the newor cold vapor nloinic absorption techniques which were likely to bo chcnpcr and just as sensitive, did not distinguish the form in which the mercury was bound. Jn the United States, the Food and Drug Administration mndc a direct comparison between cold vnpnr atomic absorption and neutron activation tech niques; the Association of Official Analytical Chemists had recently appointed n new referee for mercury residue analysis. "t. Orgnnochlurine I'ratiridr llcaiduc Aaialynia fa) Krainatiun--fry /. William Conk (Dirttinn of FwkI Chemistry, Komi and Drug Administration, Washington, V.C. 20204)........... . Much progress has been made in Uie de velopment and refinement of methods of analysis by which any or all of a large num ber of jicstir.ide residue chemicals can be detected and measured in one genera) opera tion. llicy have come to bo known aa. "multidetcction" methods of analysis. The following discussion includes DDT, y-HHC, aldriu, dicldriu, hcplachlor, endrin, clilor- dane, cndosulfan, and many other chemicals. There arc a few hundred pesticide chemicals in use; some of these consist of more than i.t, "V" . T:j;> rj?-' - ; ' WATER PCB-SD0000024947 1 . Ji 'j 1 : .r-f. A 3 10f>R .lOt.KKAI. OS Till. H.IU.C; t Vol. .`id, ,\o. | otic compound and sonic convert to a senes of alteration products whirlt may appear m residue analysis. Therefore, there is a large outulter of chemicals which chit show iip in a nioltideleetioii iiie.thod of analysis Whether or mil they me .signifirHnl ns residues, 1 heir pre-sencc must lie recognized in order not to confuse them with eipnifieanl pesticide chcmi- eals. Ideally, a general method of analysis whirl) would measure, and identify all of the significant, residues in all food products with a minimum of analytical effort and time would he desirnhle. 'Jliis is not possible at the present lime but eontc important achievement* in that direction hove been obtained to date. The developments so far have made it possible to extrart, clean up, tncnstm: quan titatively, and give a high degree of certainty to the identity of the compounds for up to 100 pestirule residue chemicals obtained from a great variety of food crops and products all in one grncrnl operation. This has been done with either extracts from individual prndurts or composites nf a large, mmilier of produels, c.g., "total diet" or "market basket." samples. The development of such proeetlures lias required a tremendous amount of e/Torl. At each point nlong the way choices had to hr. made.. As ft eonse- <iuenre of these choices, adjustments in the Intnl procedure have also had to he made. The choices nitty not necessarily httve been the best ones, hill ns the total procedure developed, (lie more difficult it Uranic tu nmlcrtnke any substitutions. Many of the steps add to the certainty of the identity of the chemicals ns well ns to the quantitative measurement. The extraction and (lie clean up procedures roust 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 operat ing parameters--arc all highly important when one is attempting to obtain quantitative response from a number of chcmirnls. Condi tions whirlt may lie satisfactory for quanti tative results on an individual rlirmirnl or n small number of chemicals nmv not yield adequate quantitation for all of many chemicals. . The collaborative study of miillidetv methods is not as straightforward a< "wet" methods, of ..analysis. 'Hie -Trial, simple procedure that has hern usru AOAC and other groii|is for de.-igu exerution oT collaliotalive studies is gi-ni not applicable to these timltidi-lectioo eetlnres. It has been the exia-rieoee of 1 and some other groups that if the ih nf the procedure are not described twa and if they are not. followed closely, g viirialions in the analy1.ira! results are tabled. At the last AOAC meeting, a spr conference was held to discuss the jimli involved in rollalmrative studies on tl methods. ]t was decided that u special reft for collaborative studies unuld lie appmiii he would work with (Ik- sju-i-i.-tlist in melt ologv- for the org.-morlilonnes, oig.inupl plintes, herbicides, rtr,, to roine op with ti procedures which are ready for rnllaborai study if possible, and then desf.rilie tl. procedures, obtain collaborators, snl.i sninplrs, receive mid tubulate data, etc. was proposed and accepted that if mrmii of llU'AC were available to piiiTieipate lltis collaborative elTort they would he w Cornell by AOAC. It. is aoliripaled tli.it I program will heeoine elleelive early in J!iH will prohnhlv include ext rael mu, elcaiu thin layer chromatography, and gas <-hi ma1ngra]ihy. Cas chromatography will involve die u of an electron capture deli-elor nml n tin niionic detector tin a split, stream nr in ta detn so that a separate but siniultaneo readmit for both organoe.hlorinrs amt organ phosplintcs will be made. The aimultanein readout from the two dclrrlnrs adds to t! certainty of the identity of the oninpomnl l-'or instance, parathion gives a large ispouse on the. thermionic, detector dm- to tl phosphorus and ft much sinalle.r response o the ICC detecUir due to the NO- group, 'll presence nod ratio of these two jienks ahii, with retention time are quite charnrlrn.-ii. Likewise, trilliion gives resj>onse by but detectors because, of the phosphorus and th chlorine in the molecule. Again the retail tin lime and ratio of the two responses eidiam itlentitiralion of the compounds Ih-io Analyzed. HittljjUMnf iiffjjjhi! ... ' - \ i,- fy tv Min wtMmimJUt TRAN 056027 WATER PCB-SD0000024948 JL. itnit tt'I'AC COMMISSION ox MKTIIOPK III' I'KSTICI I IK IIKSIIUH'. ANALYSIS If Mitt .(h) l'OAAit.tr I nl rr/rrrnrr hy Chlorinated llifibcnrh--hy C. U'iilntntk (Infliinle i>/ Atudytirnl l.hrrn i.(ry, IJri it'rrA il y of .SWIr/wf/wi, ICoAlngAengi:n PP, StAAchhidm SO, .SirrJrM ) A large immher of unknown hut chlorinerniitamiug cnmpoundn have limi detected in mlditinn In I In- ordinary pesticides in llir ihimIvmk of samples, using both (lie electron rapture. mill I In* mierneniilninctrir detector. Mass spectra of some of tbe.se. compound* olil.'iini'il mill ;i rnmhiord gas chromatngriiph-otiiss spectrometer (1,K 1 i-f)00(>) indi ruled tlml. most of the unkwnni compounds nre polyrhlnriimted biphenyls, pnlcnti.'iled Koinewii.'il- in mi Mire towards l.liow of higher ilegrct: of chlorination. A large iiiniilier of samples have lieen examined. I'olyrhlnrinsted biphenyls nre found esprciidly in fish nnd in sen birds, lull- also in conifer needles nnd in some samples of Iniinnii depot fat. Two bun dled samples of soil mid water nnd twenty samples of terrestrial mammals contained no detevtithh* nniounlK of cliloriluted biphenyls. Typical (51A'. (rures nre given by Jensen nnd Widmnik (I). Ity using it iiitviilinn method, most of the ordinary jirstirides van be re moved from extracts nnd tin* |iolyrliloriunted biphenyl will la* uimfTrrled. In thin way, it Jus lam slioivn that (wo of the major chlorinnted hijthenyl peaks overlap the peaks of ji.ji'-l >UT nnd n,;'-])))')', rrspcvtively. Hiis overlnjt is fotnul with PF-hG rohnniis, most- frequently used for the quaiititnlivc residue analyses reported in litera ture, lull, not with QF-J columns. (r) ton/irin orion o/ Identity-- . hy K. K. HIitnr (Shell Itrtrnreh Ltd., WtHulnork Agrieulture Itrinareh Centre, .SiltingfmHrap, Kent, England) - Multidelcction methods would seem to la* essential for the analysis of orgxiiochlnriiic residues liccausc of the nuiidier of chlorinated e.oniponenls which ran la*, present in any one sample. However, lliere tire problems of interpretation even when lee}inii|nes nre used nitli the resolution and sensitivity of electron capture HI Ah For example, the . resolution of the G1A'- eiilunm may not he sharp enough to Kcjnnate eoinjioiieiils; or impurities piescnt in the tcrlmieul pesticide or other natural products present, in the ex tract may compliestc the. analysis; or some inseelieides tuny thermally or catalytically decompose dining the analysis. For these reasons, residues of organochlorine eompmmds should be confirmed hy other annlyIir.nl methods. If enough material can be. isolated, infrared spectroscopy or mass s|>eetriiRr.opy can give powerful evidence of identity. However, with other methods in common use the physical basis underlying separation is very similar. KobiiiBon et al. (2) reported highly significant conr.onlnnre between the "p-valucs" for pesti cides in the various partition systems deserihed bv Jie.roxa nnd llownmn (3). Similarly, retention times on different GLC stationary phases and It/ of pesticides in various TIXJ or paper chromatographic systems are highly correlated. Further more, It/ values in paper chromatography are. closely correlated with Rf values in TLC and with p-valucs. It is possible to do a great deal of work with the in tention of establishing the identity uf a compound, but very little additional evidence wifi be gained because the results front the methods used were not independent. G1XJ retention time, an Ji( value from TIjC or paper chromatography (or a p-va)ue),_a GJXJ relent ion time of a derivative formed by chemical reaction, and pcslicidal nativity against a susceptible organism arc considered to be independent parameters giving signifi cant evidence of identity. 5. Organvplionphorus Insecticide llesiditr " Analysis The. Commission concluded that while the regulatory methods were adequate for pnraIhicm - and malnthion, clarification of the lenninal residue situation would be welcome in some instances. However, more work on the cleamtji stage for malnlliinn residues in eggs, milk, mid dried fruit was indienled. 6. Dirlilorvos Hc-sidue Analysis Ity It. A. K. Colley (Shell Krtroreh Lid., WiHHlttork Agricultural ltcirnrch Centre, Sitiingbourne, Lent, England) Five different approaches have been de veloped for the determination of tracts of diehltirvos: totul phosphorus (4, 5), cohiriin- k' A ' \ ' **' : / tSnAsaaii M TRAN 056028 nrr 77F" i i iiiV(tasWit4sssMa<aksMLisai>a^Mijldi<Mi'iiirfMifiAiii'>ita; WATER PCB-SD0000024949 Y . .1 ' i *' * 't ...............- ^ ? * / i ...I . *>J\ ' . > 1070 JOlUtNAI. Of TIIK A.O.A.C. ( Vol. 50, No. I ctrv using dinil niphoriylhydrazuie (G), alkn- Jitio resorcinol (7, 8), spcrafic hibassny (9). cholinesterase inhibition (10-12), and pas- liquid chromatography with the thermionic detector (13) and the lnicnicoululiiclrir detector (14). On the basis of sensitivity, selectivity, speed, and possibility of multidrlcclinn, the most suitable technique is CPC. Its sensi tivity (in the nanogrnm range with the. mure sensitive detectors) is nppronchod only by (lie cholinesterase, inhibition procedure, and it is unmatched on the other counts. How ever, there are two assets in the niintysis of traces of diehlorvos bv 01X7 in which improvements are needed. These are the sup pression of decomposition of diehlorvos on (lie GI>C column, and the selection of the best detector froin'(o) electron enptnrr, (b) thermionic, (c) niierocoulometrie, and (d) Hume photometric. The other sensitive method whirh is in widespread use (and which, topether with GIX7, offers additional evidence of identity) is the cholinastera.se inhibition procedure. This is a generaf method for anticholinester ases; to analytic mixtures of inhibitors, separation before Mir analysis is required. However, the volatility of diehlorvos is such that it can be 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 the analysis for diehlorvos by cholinesterase in hibition by incorporating a steam distillation step before the determination. _ Procedures for the collection1 of diehlorvos vajior from the air, extraction of residues from crops and tissues, and cleanup are available. Diehlorvos may be quantitatively removed from air by bubbling through dis tilled water. Chloroform, methylene chloride, and benzene have been used to extract di- chlorvoa residues. Partitioning from an organir solvent into water, column chroma tography on silica gel, and sleam distillation provide adequate cleanup from fatty and iionfntty materials. 7. ri|ienai)f Htiluxide lleidtUie- Amdy-i- 'Die Commission recognized the need for ich.'ihlc methods for residues of pi]>erony] biitoxide and certain allied innlriialsMi. flllctlirin ami KICK 245. 0. ItuiliillK liviilion Mrllxnl- of Aimb-, The Commission was informed that liiloniiitiounl Atomic Energy Agency I l.ll had indicated that it would be prepaid (a) provide facilities for cu-oiilinatmg Inborativo studies of existing ladinnrtivm methods, (b) assist organizations in the of activation techniques for the evaluai of Analytical methods in general, and help laboratories wishing to establish i:u. chemical techniques (15). It. was iigiecd ti while raiiioeliemiral im-Minds of .an.ih were useful for mercury and for brum, residue detenniu.'ilions, they were veiy . pensive and not. necessarily mure sensiiivr more Bjicciftc than some other irietlnMoreover, although they were often in in metnbolie. or field residue trial studs rndiochrinirnl methods were in general i ajipropriate to regulatory niclfinds of atml sis; tlie development of variona other met laof regulatory residue nnulysis was far in>, sui table. Jtesi.nKKcKK . fl) Jensen and Widnmrk, Aria ('him. Si ami in press (2) KobillHOn. J,, Itillmrdwm, A., mid l'.ts-e K. 15., "Cliemieid Identity in ll|inu>nei>i Analysis," presented at the 152nd Mn inu of the American Chemical Kurn-tv, Sep tember JUC0, at New Vork City. (3) ISowumM, M. f'.., and Horor.u, M.. Tht.* Journal 48. 013 052 (lUOa). (1) Jaws, E. Q., and Wflitcy, J). J., .t uniin.I 86. 2111-255 (lttr.l). (5) Sftlmmn, P. M.. Anal Ulirni. 36. J13 III ()8M). ......... -- (6) llngheN, J. T., Auali/hl 88, :tlK Itl'i (IMi (7) Geiger, M,, and Purer, It., 7.. A mil Cham. 171.401-1(17 (1'JCO). (8) Itiie.lder, \\\, Jhizlor, tV., mid i'iini, It. ibid. 213, 28-30 (1005). (9) Sun, Y. ami JoIiiikmi, p. It., Tins Journal 16. 621.530 (19C3). (10) Giang, P. A., and Hall. S. A . Anal, t'l-im 23,1831MKH (Htfl). (ID Giang, J*. A., Smith, P. p., and Hall. X. ,\ . J. Apr. Food Chain. 1, 02I-C22 <l!i.'il',i (J2) Porter, 1'. 17., "Vsjioim 1um->-ii< id. . . >'V-* ' > i+ysf. `4'> *y * r {-v;. IRAN 056029 ' '"y*.4 'Ci'jb'iZT *v " . ' , T' 1 " . . . . . . ** WATER PCB-SD0000024950 * .X- l r* W'---.. l. mni'>rtnmii. ru. uh'ac: commission on mktiioiis on rnsneuiK nnstmiE anai.ysis 1071 (UnVl*)", in Analytical-Mf.thodt far l'cntirirfcA, I'larit Growth Ilcgutatarf, am/ Foot/ Ailtlitirwt, Vol. J], C. 7,wcig (K.rJ.), Aeiidciiiic I'rcjw, New York( JtlM, pp. Mil-5711. (13) El-ltrfni, A. 11., mill GiulTrida, Diura, Thu Journal <8, 374-379 (19G5). (To Boone, G. H., ibid. 48. 748-752 U9C5). (15) "KiiilmimLopes in tlie Detection of JVM i- ritlc Ucaiducs", proceeding# of the I'niiti on tlie Usee of HnHioiMilopcs in tlie Delrr.tion of Pesticide ItosiHims, Inter national Atomic Energy Agcnry, Vienna. April 12-15,19GG. V> Pt l . Illl'AC CnimniiiMon on Terminal Residues Hv II. MOAN, Sccrrt.nrii In flic Commintion (laboratory of the Government Chemist, Comwill! IlmiAM*, Kt,ninfnrfl f>t-, I^mrlrm, R.Ii.l, ^Odglnncf) Tlie first meetings of tlie above Commis sion of l.lie 1'eslir.idee Section of the Applied Chemistry Division of Illl'AC were held in (lenevii in Novrmlier 10(1(1 under the ch.iirmiiushiji of Dr. 31. Uurtig. The following nceonnt. of (ho prurrcdingK is based on the iniimU'K of the meeting and on I lie ap pendixes drawn up by memlicrB nml nssoniale members of the Coinniission ns indicated. ' ' 1. Terminnl Curhninnlc Itruliinc Tito commission discussed tlie present position regarding knowledge of the nature of the. torniinnl residues of carbamates, iu- elndiiip eiirbaryl, ns indientcd in the cvnlun- tious lielmv, nml set up a tvorkinp proup to further this knmvledpc with particular re gard to the uses of carbamates in food prmluctiuu. '. (1 hralliminn--lr /, ITilliom Cook fflit'lilim of Nmwl Chrmittry, food and ' l>ru( Ailmininralion, Watli/n*toh, P.C. 2020f) ~ ' ' lu the earlier studies on enrhnryl residues, holh earharyl and its hydrolytic prodnrl, l-naphthol, were considered. Kesidue studies oil many crops showed (hat the quantity of I-na]>hthol was small and difficult to $e)ininie fiom earharvl. Tims, it was considered llint 1-imjilitlm] need not lie measured separately fiom earharyl. Tolerances for cnrlinrvl e.-tablishcd in the United Stales arc based on the assumption that tlie major part of the rraidne is tlie intact carbamate. Since the establishment of the inilinl toler ances for carbnryl, work has been done which may have sonic bearing on the quanti tative and qualitative aspects of tlm residue. bight, including artificial light and sun light, changes carbnryl. 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 cllianol or hexane solutions of some niclhylcArbnmate insertir.ides, includ ing carbnryl, pave a variety of choliiirslerase- inhibiting derivatives when exposed In either artifieinl light or sunlight. The producls were separated but not identified. Abdcl-Wahrb and eoivorkers rcjxtrted that the nature of the surface, the light, and the compound affected the rate of conversion of earharyl and other carbamates in vitro in the solid state. ......... . ... .' . / ' Since neither the qualitative nor quantita tive aspects of pholodecomposition of carba mates have born established, the significance of these studies in relation to current and future tolerances for earharyl must await further study. Whitehurst, et al. (4), using the colori metric method of analysis sensitive to ear- baryl, l-naphthol, and J-nnphtho) conjugates, concluded that when cows were fed a diet containing earharyl, no residues, to the limit of the method, were found in milk. This was . , 1 ~ ' I. i. !!. . ,560X0 V. TSPatp" r:v > at.Art. T't'.m/k -yjfiUgBjj-'HyW j 1111 .UMlf r, siyvin WIIF.I ayi Min'ir iiifi i axsfasAnai a. :if.i . WATER PCB-SD0000024951