Anal. Chem. 1993, 65, 40R-54R
Pesticides Joseph Sherma Department of Chemistry, Lafayette College, Easton, Pennsylvania 18042 Review Contents Introduction Books and Reviews General and MulticlasslMultiresidueMethods Sampling, Extraction, and Cleanup Gas Chromatography and Supercritical Fluid Chromatography High-Performance Liquid Chromatography Thin-Layer Chromatography Miscellaneous Techniques Organochlorine Pesticides Organophosphorus Pesticides Carbamate and Carbamoyl Insecticides Herbicides and Plant Growth Regulators Fungicides Pyrethrins and Pyrethroids Fumigants Miscellaneous Pesticides Industrial Chemicals Related to Pesticides References
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INTRODUCTION This review covers the literature on pesticide analysis abstracted and/or published in the period between December 1, 1990 and December 1, 1992. The major sources of information were the primary abstracting journals Chemical Abstracts and Analytical Abstracts. Journals that were searched directly includeJourna1 of the AOAC International, Journal of Agricultural and Food Chemistry, Bulletin of Environmental Contamination and Toxicology, Analytical Chemistry, Analyst, Chromatographia, and Journal of Chromatography (including its bibliography issues). The review is devoted mainly to methods for the determination of residues of pesticides in a wide variety of sample matrices. Areas that are included are listed in the Review Contents. Some coverage is given to the analysis of related industrial chemicals, such as PCBs dioxins, and furans, but pesticide formulation analysis is not reviewed. The attempt was made to choose only the most important publications describing significant advances in methodology, instrumentation, and applications that would be readily available to readers of this journal. Abstract citations are given for references from the more obscure journals and those not published in English. Abbreviationsused throughout this review are listed in Table I. Pesticide abbreviations, common names, and trade names are used according to the Pesticide Dictionary of the Farm Chemicals Handbook '92,Meister Publishing Co., Willoughby, OH. Multiresidue methods are used by federal (FDA, USDA, EPA) and state regulatory and monitoring laboratories to analyze a range of pesticide classes in a variety of sample matrices. Multiresidue and single residue methods generally consist of the followingbasic steps: extraction of the analyte(s) from the sample matrix; cleanup to remove interfering coextractants; conversionof the analyte to a readily analyzed derivative (if needed); separation of the analytes from each other and any remaining interferences, usually by GC or HPLC; detection; quantification by comparison of the detector response of the sample to that of standards; and confirmation of results using an ancillary method, such as MS. Among the more widely used MRMs and SMRMs (which are suitable for pesticides of only a single class) are those of Mills; Mills, Onley, and Gaither; Storherr; Luke; and Krause (I). The Luke method, which involves an aqueous acetone 40R
Joseph Sherma received a B.S. in chemistry from Upsala College, East Orange, NJ, in 1955 and a Ph.D. in analytical chemistry from Rutgers University in 1958. His thesis research in ion exchange chromatography was under the direction of the late Wm. Rieman 111. Dr. Sherma joined the faculty of Lafayette College in Sept 1958 and is presently John D. & Frances H. Larkin Professor and Head of the Department of Chemistry and is in charge of three courses in analytical chemistry. Dr. Sherma independently and with others has written or edited over 370 papers, chapters, books, and reviews covering chromatographic and analytical methods. His current research interests are in quantitative TLC, mainly applied to lipid analysis, pesticide residues, and food additives. He is editor for residues and elements of the Journal of AOAC International.
universal extraction method, minimum cleanup, and deter- . mination by GC with specific detectors, allows determination of the largest number of pesticides and is probably the MRM that is most widely used by regulatory agencies. SRMs, many of which are developed by pesticide manufacturers for submission to EPA as part of the pesticide registration process, are used to analyze pesticides or samples not covered by the multiresidue methods. During the past two years, significant progress and/or promise of future developments and increased use was noted in the following areas of pesticide residue analysis: simplification, miniaturization, and improvement of sample extraction and cleanup methods: e.g., universal microextraction procedures,SPE on cartridges or disks to replace liquid/liquid extraction, selective extraction with SFE, and increased use of sweep codistillation; capillary and wide-bore capillary columns to replace packed columns, temperature-programmed injectors, and ion trap MS, FTIR, multielementspecific atomic emission, chemiluminescence, and MS/MS detectors for GC; HPLC for thermally labile and/or polar pesticides and metabolites, wider use of ion and ion-pair chromatography, development of additional postcolumn derivitization techniques, and improvement of HPLC detectors (e.g., laser fluorescence, electrochemical, photoconductivity), and HPLC/MS interfaces (thermospray, electrospray, ion spray); increased use of flexible and user-friendly automation and robotic systems (2,3)for sample preparation and application and chromatographic and spectroscopicdata handling; SFC with different modified supercritical fluids and improved detectors for analysis of nonpolar and polar analytes and the on-line combination of SFE and SFC; capillary zone electrophoresis for the highly efficient separation of ionizable analytes; expanded research on the development of reliable enzyme immunoassayprocedures for pesticides and metabolites, especially in the areas of sample preparation, validation, multiresidue capability, and commercial kits and methods for field screening; and biosensors, which generally involve an immobilized enzyme or antibody as the basis of selectivity, for use as portable pesticide probes. Immunoassayis especially valuablefor the sensitive, selective, and rapid screeningof samples, followed by confirmation and quantitative analysis by a method such as GC/MS for those samples that screen positively. Trends in pesticide analytical methods were reviewed by Cairns (4),Seiber (5),and Conaway (6).
A number of informative feature reports relating to pesticide analysis have been published in the past two years. Ames (7)discussed pollution, pesticides, cancer, and the
QQQ3-27QQ/ 93/Q365-QQ4QR$l2.QQ/Q 0 1993 American Chemical Society
PESTICIDES Table I. Abbreviations ACS AFID AMD c-8 C-18 CGC
CI CIEIA CN
EEC ECD E1 EIA ELCD ELISA EPA ETU FAB FDA FIA FID FIIA FPD FT GC
GPC HPLC HPTLC HR i.d. IR ITD MRMs
MS
American Chemical Society alkali flame ionization detector automated multiple development Ce alkyl-bonded silica gel Cls alkyl-bonded silica gel capillary (column)gas chromatography chemical ionization competitive inhibition enzyme immunoassay cyano-bondedsilica gel European Economic Community electron capture detector electron impact enzyme immunoassay electrolytic conductivity detector enzyme-linkedimmunosorbent assay Environmental Protection Agency ethylenethiourea fast atom bombardment Food and Drug Administration flow injection analysis flame ionization detector flow injection immunoanalysis flame photometric detector Fourier transform gas chromatography (gas/ liquid chromatography) gel permeation chromatography
high-performance liquid chromatography high-performance thin-layer chromatography high resolution internal diameter infrared ion trap detector multiresidue methods mass spectrometry
MSD NI
mass selective detector negative ion nuclear magnetic resonance
NMR NPD
nitrogenlphosphorus-selective (thermionic) detector
oc
ON
OP OPA PAH PCB PCD PCDD PCDF PCP PI ppb PPm
PPtr PT PTFE PTV RIA RP SEC SFC SFE SIM SMRMs SPE SRMs TCDD TLC USDA
uv
organochlorine organonitrogen organophosphorus o-phthalaldehyde polycyclic aromatic hydrocarbon polychlorinated biphenyl photoconductivity detector polychlorinated dibenzo-p-dioxin polychlorinated dibenzofuran pentachlorophenol positive ion parta per billion parta per million parta per trillion programmed temperature poly(tetrafluoroethy1ene)
programmed temperature vaporizer radioimmunoassay reversed phase size exclusion chromatography supercritical fluid chromatography supercritical fluid extraction selected ion monitoring selective multiresidue methods solid-phase extraction single residue methods tetrachlorodibenzo-p-dioxin
thin-layer chromatography United States Department of Agriculture ultraviolet
esticide regulatory process and stated that FDA food assays Kave found residues of 105pesticides and industrial chemicals the United States intake of which averages0.09 mg per persod per day, about half of which is composed of noncarcinogenic compounds. He compared this to an intake of 1500 mg of natural pesticides from food, including many rodent carcinogens, and called for a rethinking of current regulato policies and pesticide screenin programs. Clement (8) Xscussed advances in ultratrace ioxin and dibenzofuran analysis over a period of 30 years, including a description of the compounds, history and evolution of analytical methods, validity of the numbers produced by the analyses, and future prospects. Graham (9)described study design, types of studies, protocol development, and data interpretation in groundwater and well water monitoring for pesticides. Three pa ers (10-12) considered the relationshi between analytic$ chemistry, environmental science, a n i t h e “environmental revolution”. Topics such as analytical techniques and the role of the analytical chemist, public policy and perception, uncertainty of results and limitations of environmental analysis, the concept of “zero concentration”, and dose/response relations and cancer risk assessment are covered in these thouehtprovoking publications. An article in The New York Times (July 17,1991,.p D1) reported on the first EPA approval for genetically engineered bacterial pesticides, the number of which will certainly increase in the future. Undergraduate and aduate schools are currently not producing nearly enough cfemists with the training necessary for the analysis of chemical pesticides, and these new biotechnologically produced products will make the problem more severe by requiring analysts to have skills in biology and biochemistry as well as traditional trace residue analysis.
critical fluid extraction methods), multiresidue approaches (analysisof fruits and vegetables;determination of carbamate, OP, and ON esticides; two-dimensional CGC; headspace methods for d%hiocarbamates), and emerging technologies (fiber optic spectrosco y, enzyme-linked com etitive immunoassay, ion trap M{ hyphenated metho& HPLC/MS, immunochemical methods) (AI). The second volume, Comprehensive Analytical Profiles of Important Pesticides, includes chapters with information on general properties, formulation analysis, and residue analysis for pyrethroids, hexaconazole, pyrifenox, abamectin, alachlor, clomazone, fluazifop-p-butyl, isoxaben, oryzalin, flur rimidol, and fumigants (A2). Volume 2 of the Manual of gesticide Residue Analysis (A3) and books containing mass spectral and GC data of pesticides, pollutants, and metabolites (A4);compilations of EPA’ssampling and analysis methods and database (A5, A6); EPA’s fact sheet database (An; a book on the toxicology and use of OP and carbamate compounds in relation to wildlife (A&; and a guide to environmental sampling and analysis (A91 were published. Volumes 442 and 461 (1990) of the ACS Symposium Series contained a large number of papers on the immunoassay of pesticide residues. The Journal o Pesticide Science (Elsevier) began publication of an Englisdlanguage international edition commencing with volume 17 (1992). Two general reviews of pesticide immunoassays (A10,A l l ) and two reviews of GC/MS in environmental analysis (A12, A13) were published. The analysis of pesticides at low levels in drinking water (A14) and the occurrence, handling, and chromatographic determination of esticides in the aquatic environment (A15) were reviewed. &her reviews on specific methods or applications are cited in the appropriate sections below.
BOOKS AND REVIEWS
GENERAL AND MULTICLASS/ MULTIRESIDUE METHODS
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The F i t two volumes in a new seriestitled Modern Me tho& for Pesticide Analysis were published by CRC Press. The first volume, Emerging Strategies for Pesticide Analysis, contains sections on extraction and cleanup (microextraction methods, solid-phase partition column technology, super-
The use of certified reference materials for pesticide residue determination in foods (81)and the hardware and software for computer-aided analysis of pesticides (82) were described. Detection and determination limits for residue analysis were ANALYTICAL CHEMISTRY, VOL. 65, NO. 12, JUNE 15, 1993
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derived according to a new approach published by Deutsche Forschungsgemeinschaft (B3). An overview of quality assurance in environmental trace analysis (B4)and application of the quality control chart principle to routine pesticide residue determination in water (B5) were published. The following multiclass/multiresidue determinations in water were reported: 50 pesticides by mixed-adsorbent SPE (2-18 SPE with ca illary GC and HPLC for and GC/MS (B6); 12 triazole and pyrimidine pesticifes in groundwater (B7); HPLC determination of polar pollutants in surface water using membrane extraction disks for on-line trace enrichment (B8);atrazine, alachlor, and carbofuran in well water by immunoassay (B9);89 pesticides in groundwater and river 35 water b liquid-solid extraction followed by HPLC (BIO); pesticiLs in drinking water using graphetized carbon black 45 N- and P-containing cartrid e extraction and HPLC (B11); pesticiies at 6 concentration levels in finished drinking water by CGC with NIP detection (collaborative study) (BIZ);39 types of pesticides by GC/MS-SIM (B13);22 pesticides in drinking water by SPE and HPLC with diode array detection (B14);54 polar pesticides in river water by on-line trace enrichment on a resin precolumn and HPLC (BI5); 20 pesticides in surface water by GC with CIMSiion trap over 100 analytes from the EPA National detection (B16); Survey of Pesticides in Drinking Water Wells by HPLC with postcolumn photolysis and fluorescence,electrochemical, and photoconductivity detection (BI7);and triazines and OP pesticides by C-18 SPE CGC (BIB). Multiresidue analysis of pesticides by diode array detector HPLC after SPE was reviewed (B19). Strategies for pesticide control in groundwater and drinking water (B20)and methods development and implementation for the EPA National Pesticide Survey (B21) were discussed. The following multiclass/multiresidue methods for fruits and vegetables were published: comparison of ethyl acetate and acetone extraction (B22);simultaneous determination of clofentezine, fenoxycarb, and hexythiazox on apples and pears by C-18 Sep-Pak cleanup and C-18 HPLC (B23); benodanil, bromopropylate, chlorobenzilate,chloropropylate, dichlofluanide, procymidone, and propachlor in onions and leeks by two-dimensional CGC and enzyme inhibition prior to sample cleanup (B24);folpet, carbaryl, dimethoate, azinphos-methyl, methyl parathion, fenitrothion, phosalone, and chlorpyrifos in citrus fruits by HPLC with diode array detection (B.25);a rapid screen for 110 pesticides in produce by GC with ECD, AFID, and FPD and HPLC with fluorescence detection (B26);Florisil column extraction of carbamate, OC, OP, pyrethroid, triazine, urea, and miscellaneous pesticides prior to GC (B27);21 OC, OP, and carbamate pesticides in 6 representative fruits and vegetables by acetone blending, cleanup by RP solid extraction, and GC and HPLC determination (B28);143 compounds in 13 crop samples by GCI MS screening after acetonitrile extraction and partitioning with saturated aqueous NaCl solution (B29);19 nonvolatile and thermally labile pesticides by thermospray HPLC/MSSIM (B30);GUMS and HPLCiMS after a single extraction step for determination of 20 pesticides with oncogenic potential in 9 cro s (B31);21 pesticides by extraction with acetone, GPC, anfGC/MS (B32);23 N-containing pesticides by acetone extraction, hexane partitioning, GPC, and CGCI MS (B33);and 9 halogen-containing pesticides on peppers and cucumbers by extraction with ethyl acetate and sodium sulfate, Florisil cleanup, and CGC-ECD (B34). General screening methods for esticides in soils involved methanol/acetone sonication and 8GC-FID and HPLC-diode array UV (B35)or Soxhlet extraction, evaporation, filtration, preconcentration on a (2-18 cartridge, and GC-NPD or GC/ MS (B36). C-18 HPLC-UV(2OOnm) after C-8 SPE was used for determination of 15 pesticides in wine (B37). Seventeen OC and OP pesticides in anhydrous lanolin and lanolincontainin pharmaceutical preparations were determined by utilizing 8 P C cleanup with wide-bore capillary GC-ELCD and -FPD and confirmed by GC/MS (B38). Nine polar pesticides were determined in cereals using RP-HPLC column switching for cleanup and determination, with programmable UV detection (B39). A GPC cleanup method for determining organohalides in animal fats was evaluated, and 13additional compounds were approved for inclusion in the method for use in the USDA Domestic Residue Monitoring Program (B40). 42R
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SAMPLING, EXTRACTION, AND CLEANUP Trends in techniques for the extraction of dru s and pesticides from biological specimens were reviewed (81).An earlier method involving acetone extraction and charcoal/ silica gel microcolumn cleanup was modified to reduce sample, time, and solvent requirements (C2). The stability and recovery of 84 pesticides and 12 PCBs during cleanup procedures using sulfuric acid and Florisil were studied (C3). Leaf-punch, whole leaf, and surface wipe methods were compared for sampling pesticide residues on leaf surfaces (C4). Sorption and elution characteristics of selected pesticides on 10 sorbents were studied (C5). Drying with anhydrous MgS04 instead of nonpolar solventswas introduced into the on-line extraction method using the binary solvent system water plus acetone to reduce solvent use and disposal (C6). A safer and less tedious procedure for preparing diazomethane for methyl esterification of samples prior to GC was described (0.Studies of 147 EPA National Pesticide Survey analytes demonstrated the stability of 121 compounds in stored well water samples and general stability in stored sample extracts (C8). Centrifu al vacuum concentrators were successfully applied to resifue analysis (C9).A computer program was developed for the rational optimization of automated sample cleanup with column switching in residue analysis (CIO). One of the clearest trends in the past two years was the greatly increased use of solid-phaseextraction or solid-matrix partition using cartridges and disks to replace conventional liquidiliquid extraction. The following studies of these methods for pesticide analysis were reported: separation of OC residues from fatty materials by partition between hexane and acetonitrile on Kieselguhr disposable cartridges ( C I 1 ) ; the use of SPE to simplify and standardize GC environmental analysis ( C I 2 ) ; C-8 SPE for extraction of carbaryl and malathion from pond and well water (C13);extraction of phenylurea herbicides (C14) and OP pesticides (C15) from water on C-18 cartridges; replacement of Attagel by SPE cartridges in cleanup procedures for OC pesticides in raw (3-18SPE of seven synthetic pyreagricultural crops (CI6); throids (CI 7 ) and eight triazine herbicides (C18)from human urine and plasma; use of solid bonded-phase extraction as an alternative to liquid/liquidpartitioningfor crop analysis (C19); and cleanup of some OC and pyrethroid insecticides by automated SPE coupled to CGC-ECD (C20). There was also much more use of supercritical fluid extraction in pesticide residue analysis during the past two years. The following applications were described: SFE of polar analytes using in situ chemical derivatization (C21); on-line coupling of SFE with multidimensional microcolumn HPLCiGC (C22); assay of residues in meat products b combined SFE-enzyme assay (C23);SFE separation of 08 pesticides from fats based on alumina or silica column adsorption with COZ or methanol/COz supercritical mobile phase (C24);comparison of supercritical fluids for extraction of PCBs and PAHs (C25); enhanced SFE with COz of pesticides from foods using pelletized diatomaceous earth (C26);in situ SFE and derivatization of pentachlorophenol from soils (C27); studies of the SFE of 41 OC and 47 OP pesticides in environmental analysis (C28);development of a flexible, on-line SFE-GC system (C29);comparison of SFE with classical sonication and Soxhlet extractions for selected pesticides (C30);postextraction solvent flush of the pressure restrictor in SFE of plant tissue samples (C31);and analysis of 4-nitrophenol and parathion in soil using SFE and immunoassay (C32). The following studies of GPC or SEC were published: miniaturization of SEC by use of a 2-mm-i.d. column for OC pesticide cleanup ((233);a displacement pump procedure to load extracts for automated GPC (C34);development of online SECiGC (C35, C36); reducing solvent consumption in automated GPC by modification of the AutoPrep 1002 ((237); and two cooperative trials of a GPC method for isolation of pesticides from fats and oils (C38). The following procedures for pesticide residue determination in water samples were reported: SPE for OC pesticides (C39,C40);C-18 SPE of atrazine from small sample volumes ( C 4 I ) ; application of a one-step extractor/concentrator in environmental testing (C42);multiresidue determination of triazine herbicides and OP insecticides by C-18SPE and GCI
PESTICIDES MS (C43); investi ation of the concentration efficiencies of macroreticular an8 Ambersorb resins (C44);erformance of the Gouldenlar e-sample extractor (C45); on&e continuousflow system utifizin? heptane extraction and a PTFE membrane separator, wlth HPLC-UV and HPLC/MS (C46); extraction of insecticides with unloaded polyurethane foam columns (C47);SPE with membrane disks (C48,C49);and automated sample reparation using supported li uid membranes for HPLC Betermination of sulfonylureaRerbicides ((250).
A variety of sorbents were tested for trapping efficiency of pesticides from air (C51,C52). Reported methods for sample preparation in pesticide soil analysis included extraction from soil leachate using sorbent disks (C53);SPE (C54);an automated extraction system (C55); enzymic pretreatment for extraction of starch-encapsulated pesticides (C56);and resin extraction of alachlor, atrazine, and metribuzin (C57).
GAS CHROMATOGRAPHY AND SUPERCRITICAL FLUID CHROMATOGRAPHY The primary method for residue analysis continues to be GC with a Selective detector, and use of capillary column GC (capillary GC) is being reported ever more frequently. Extraction, cleanupb solvent partitioning and li uid column chromatography, andy derivatization, when nee ed, remain normal steps for sample preparation. SFC is bein applied for residue analysis to an increasing degree but is stit a minor method. A GC system for identification of halogenated pesticides by linear temperature-programmed retention indexes using n-alkanes as standards was described (01). A screenin program based on retention indexes of 170 commonly use pesticides on an OV-1 column was reported (02). Temperature-programmed GC separations of pesticides were optimized usink a central composition design (03). Relative retention times versus chlorpyrifos were measured for 58 pesticides on 8 liquid phases, and RRT diagrams were effectively used to establish efficient operating conditions for pesticide analyses (04).Retention times relative to aldrin were reported for 38 OC pesticides and PCBs on three widebore capillary and two packed columns (05). T h e sensitivity of GC/MS determination of pesticides and PAHs in water was improved by usin a cold injection system (06). Optimization of sample intro uction was studied for pesticide determinationsby capillary GC using a two-column, two-detector system (07). The long-term stability of CGC res onses to pesticides in a complex food matrix was studied w i t , three injection techni ues: programmed-temperature vaporizer, hot-splitless, an cold on-column (08).Largebore capillary columns were shown to be a plicable for accurate and precise pesticide analyses (09,&0). The followin detection methods were ap lied for pesticide analyses: F T d using a liquid nitrogen co d-tra pin techni ue (011); tandem mass spectrometry (GC/M&M& with cohionally activated dissociation and multireaction monitorin? (012);electrolytic conductivity detector for determination of toxic N-containingfood contaminanta separated b open tubular column GC (013);a new sulfur-selective ciemiluminescence detector offering hi h sensitivity, linear response over 5 orders of magnitude, an!I equimolar response for S compounds (014);and the multielement-selective microwave induced plasma atomic emission detector (015017). PCBs and pesticides were determined with a dual CGCdual detector (ECD and NPD) system (018).Procymidone was determined in wine by double-polarity GC with simultaneous double detection (D19).A dual-channel evaluation system was used for quality assurance in high-resolution GC of pesticides in environmental and drinking water (020). Residue analysis in foods was performed by two-dimensional The advan GC with three selectivedetectors (021,022). and disadvantages of coupled HPLC/HPLC and HPLC/ C were evaluated (023). The following papers described SFC techniques and applications related to pesticide analysis: solvent-vented injection in the analysis of esticides b capillary SFC (024); the use of modified mob& phases (Lb); acked-ca illary coupred SFE-Sk! for SFC using P-selective detection (026); determinationof fenitrothion, esfenvalerate, and diniconazole
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in soil and plants (027);and SFC with sulfur chemiluminescence detection (028).
HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY Use of a C-18 column and UV detector is the predominant approach for HPLC analysis of esticide residues, but applications of systems involvin m3tiple columns and other detectors, includ' HPLC/M$ are growing rapidly. The increased use of #LC is main1 the result of ita suitability for determining thermally labig and polar pesticides that require derivatization prior to GC and ita compatibilitywith on-line precolumn cleanup and postcolumn reaction systems. A review of the analysis of pesticide residues in foods by HPLC contains 242 references (El). Phenoxy acid herbicideswere determined in surface water by cleanup and analysis on dual polymeric HPLC columns (E2).HPLC with column switching was shown to enhance the sensitivity and selectivity of pesticide residue analysis and to have a high potential for automation (E3),as was illustrated by the automated determination of flucycloxuron in crop and environmental matrices with a column switchin system consisting of an internal surface RP column, a pheny bonded precolumn, and a C-18 analytical column (E4).A method for optimization of ternary mobile- hase gradients was illustrated for the RP separation of phenyyurea herbicides 035). An HPLC postcolumn derivitization integrated retention detection system was used for the determination of carbaryl and ita hydrolysis product, 1-naphthol 036). The UV photolysis of several classes of N-pesticides was examined with a view toward develo ing a method for hotoinduced fluorescence detection in PIA and HPLC (Ep7). A sulfurselective chemiluminescence detector was interfaced with packed capillary column HPLC and used for analysis of thermally labile thiocarbamate pesticides (Et?). Anilines derived from pesticides were determined by HPLC with an electrochemicaldetector (E9).Amperometric detection in the reductive and oxidative modes was compared with UV detection for HPLC analysis of nitrophenol pesticides (ElO). The different approaches to HPLC/MS for enhapcin structural information in sticide analysis were renewed (Ell).The influence of g f e r e n t eluenta in positive and negative ion modes of thermospray HPLC/MS was studied with carbamates,chlorotriazines,phenylureas, henoxyacids, and OP and quaternary ammonium compounis (E12).One hundred compoundsfrom the EPA National Pesticide Survey list were analyzed by particle beam HPLC/MS, four different commercial nebulizers were compared, and pesticide fragmentation patterns were described (El3).
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THIN-LAYER CHROMATOGRAPHY A general review of esticide analysis by TLC (Fl)and reviews of modern HPbLC pesticide analysis using AMD (F2)and analyticalfield screening by TLC (F3)were reviewed. The following sticide detection reagents were re orted: dapsone for cartamate arsenic trichlori6sulfuric acid (F4); sodium hydroxide/cupric acetate/phosphinsecticides (F5); omolybdic acid for pyrethroid insecticides containinga nitrile group (F6);cobalt acetate and o-tolidine for endosulfan and diazotized p-nitroaniline and diazotized phosphamidon (F7); p-aminoacetophenone for carbaryl (F8);and zinc chloride/ diphenylamine for OP and carbamate insecticides (F9). The following pesticide TLC or HPTLC separations and determinationswere published: specific detection of carbaryl by formation of the oxime, treatment with @naphthol, oxidation with nitric acid, and silica gel TLC (PI0);separation of ethalfluralin, benfluralin, and trifluralin by double development on alumina layers with hexane mobile phase (FlI); metrifonate and DDVP in rat blood, brain, and liver homocarb 1in water by silica gel TLC, detection genates (FI2); with p-nitrobenzen%azonium fluroborate, and spot area measurement (F13);separation of carb 1 from related compounds by multi le development on x c a gel G lates (F14); separation of Eerbicides on mixed silica gel/c cium sulfate plates (FI5); separationof deltamethrin,cypermethrin, and fenvalerate on silica gel plates F t h hexane/acetone/ethyl acetate mobile phase and 2,4-dinitrophenylhydrazineand
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phosphomolybdate chromogenic reagents 0716);and separation of phenylurea and triazine herbicides by overpressured layer chromatography with a binary mobile phase (FI7).An optimized screening system for 170 pesticides was based on TLC detection in combination with GC and UV spectroscopy as independent techniques (FI8). Over 100pesticides, mostly fungicides and insecticides, were determined in standard solutions by HPTLC employing modern spottin and evaluation techniques; R, values in standardized mokle phases and sensitivity limits for three detection reagents were tabulated (F19). It was shown that HPTLC is suitable for confirming GC analyses of fruits and vegetables (F20). The following quantitative HPTLC determinations with densitometric scanning were reported: chlorpropham, propham, and thiabendazole residues in potatoes on C-8 layers (results compared well with HPLC) (F21); abscisic acid produced by cyanobacteria, with cleanup on a C-18 Sep-Pak cartridge, silica gel HPTLC with toluene/ethyl acetateiacetic acid (25:15:2) mobile phase, and fluorescence labeling (F22); OP insecticides in water usin C-18 SPE, silica gel HPTLC, and detection with N,2,6-tricdorobenzoquinoneiminereagent prior to scanning (F23);and 18 OP pesticides by HPTLC with detection at 0.1-5-ng levels by enzyme inhibition (F24). Computer-assisted methods were reported for optimization of mobile-phase selectivity in the HPTLC of N-containing pesticides (F25). Automated multiple development, one of the most promising modern instrumentalized HPTLC procedures, was described and applied to the determination of crop protection agents in drinking water (F26-F28). Optimized mobile-phase gradients were designed for the AMD separation of OC pesticides and phenols (F29). The sensitivity of thiazafluron determination in water by Hill photosynthesis reaction inhibition was 20 times greater than that of the standard TLC method; chloroplast homogenate preparation and the TLC procedure were described (F30).
MISCELLANEOUS TECHNIQUES A Lotus 1-2-3spreadsheet template was designed to make time-dependent adjustments in standard regression lines used for calculatin esticide concentrations in order to compensate or! HPLC detector responses ( G I ) . A visible for drifting & spectrophotometric method based on formation of an orange polymethine dye was applied to the determination of kelthane in water, milk, and ve etables (G2). Spectrofluorometry was used to determine asu am in peaches following fluorescamine fluorogenic labeling (G3) and azinphos-methyl in soils (C4) and quinalphos in citrus fruits (G5)following generation of a fluorophore by alkaline hydrolysis. Trace analysis of fluorinated pesticides in food products was carried out by F-19 FT-NMR (G6),and OP insecticide residues in crops (G7) and soil (G8) by P-31 FT-NMR. A review with 172references covered environmental applications of GC-FTIR spectrometry, including analysis of pesticides, PAHs, PCBs, and dioxins (G9), and the applicability of cryotrapping GC-FTIR in environmental analysis was studied (G10). The following aspects of pesticide analysis by MS were published: positive and negative ion californium-252plasmadesorption MS of polar a rochemical metabolites (G11); spectral characteristics a n d data precision in the methane chemicalionization of pesticides by ion trap technology (G12); improvements in ion trap chemical ionization performance by application of a modified scan function for rejection of undesired ions formed at the beginning of the reaction ionization period (G13);detection of 2,4-D and malathion on plant leaf surfaces by use of a molecular primary beam secondary ion MS instrument (G14);a review and discussion of applications of FT-ion cyclotron resonance MS in pesticide analysis ((215);fast capillary electrophoresis-ion spray MS determination of sulfonylureas (GI6);effect of mobile-phase variations in thermospray HPLCiMS of carbamate and chlorotriazine pesticides (GI 7); use of positive and negative ion thermospray MS for determination of OP pesticides and their oxygen analogs (G18); automated pesticide screening by use of a macroprogram to compare spectra acquired during GUMS with those in designated spectral libraries containing a limited number of target compounds (GI9);and detection of 1,3,5-triazine derivatives in crop samples by thermolysis atmospheric pressure ionization tandem MS (G20).
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The number of immunoassay rocedures reported for pesticide analysis increased si igantly during the latest two-year period, and many of t g s e methods are included in the following sections devoted to specific pesticide classes. Three papers reported the use of FIIA for determination of triazine herbicides in water ( G 2 1 4 2 3 ) . A cholinesterase inhibition assay was devised for screening carbamates and OP insecticides in water (G24)and a chloro last bioassa for determining herbicides in water (G25). A) review w i d 34 references dealt with various biosensor devices for pesticide analysis in water (G26),and a piezoelectric immunobiosensor for atrazine in drinking water was developed (G27). Glyphosate and its metabolite, (aminomethy1)phos honic acid, were determined in serum usin capillary electropRoresis (G28), and high-performance capiiary electrophoresis was optimized for separation of nine plant growth regulators using an overlapping resolution mapping scheme (G29). Polarography was used to study the adsorption of acifluorfen and thiram on lignin (G30).
ORGANOCHLORINE PESTICIDES The section below on herbicides contains information on the determination of chlorinated herbicides. Packed and capillary column GC with electron capture detection has been reported most often for residue analysis of OC insecticides, with occasional application of the electrolytic conductivity detector. As with all pesticide classes, MS is the primary confirmatory method. General Procedures. Fifteen OC pesticides were determined in blood serum by petroleum ethedacetone (91) The extraction, treatment with H2S04, and GC-ECD (HI). detection limits for determination of OC pesticides and PCBs in blood serum were optimized to subnanogram per milliliter levels for epidemiologicalstudies involvinglow-level exposures (H2). Matrix solid-phase dispersion extraction with GC-ECD was used to screen nine OC pesticides in catfish muscle tissue (H3)and beef fat (H4). OC pesticides in milk were determined H6). by extraction, C-18 SPE, and capillary GC-ECD (H5, Forty-five OC pesticides listed in EPA method 8081A were chromatographed on two pairs of GC columns connected to an inlet splitter and se arate ECDs, and 13 additional compoundswere evaluateffor suitabilit as internal standards (H7). EPA method 1625 was extendeBfor determination of low pptr concentrations of 4,4’-DDT, -DDD, and -DDE in A study waters and soils by isotope dilution GC/MS (H8). was made to optimize the temperature program and flow rates for dual CGC analysis of EPA method 608 pesticides (H9). A system was developed for low-level screening of 31 OC pesticides using simultaneous injection on two dissimilar capillary columns with electron capture and electrolytic conductivity detectors (HIO). OC pesticides and metabolites were extracted and concentrated from serum usin C-18 SPE, followed by capillary OC and 8 P pesticides were determined in GC-ECD (HII). lanolin by capillary GC with detection by electron capture, flame photometric, MS, and atomic emission techniques (HI2). OC and OP pesticides in cocoa beans were determined by GCIMS-SIM after treatment with H2S04 and hexane extraction or extraction with the Unitrex apparatus (H13). The CGC determination of OCs in vegetables and soilinvolved cleanup on SPE cartridges filled with silica, deactivated Florisil, and sodium sulfate (HI4).OC residues in honey were determined by hexane extraction, Florisil Sep-Pak Mussels were analyzed for cleanup, and CGC-ECD (H15). OCs and PCBs by acetonitrile extraction, artitioning with hexane, cleanup on a Florisil Sep-Pak, and 8GC-ECD (H16). Residues of 15 OC residues were determined in animal feed An immunoassay by (2-18SPE and dual-column GC (H17). kit was used to screen cyclodiene residues in apple, tomato, and lettuce at 0.01-0.03 ppm levels (H18). Specific Procedures. Chlorpyrifos and its metabolite, 3,5,6-trichloropyridin-2-01, were determined in dates by acetoneiwater (101) extraction, cleanup by solvent partitioning, and GC-NPD and -Hall ELCD (H19). Chlorpyrifos was isolated from contaminated fish by silica gel column extraction prior to GC-ECD (H20). Chlorpyrifos-methyl was determined at ppb levels in wheat by SFE and on-line couded microcolumn GC/LC (H21).
PESTICIDES The followinganalyses of toxa hene were reported: in codliver oil by integration of the HgGC-ECD pattern (H22);in fish by pentane/methylene chloride (1:l)extraction, cleanup on deactivated alumina and silica columns, and GC/ne ative ion CIMS (H23);in fish oils by HRGC-ECD or HRGC/&IMS (H24); and in aqueous samples by SPE and HRGC-ECD with PTV injection (H25). Diflubenzuron was determined in leaves by GUMS using deuterated diflubenzuron as internal standard (H26). Mirex was quantified in human blood serum containin PCBs b packed column GC, with confirmation by HRdC/HRMg (H27).Chlorsulfuron in milk was determined by blending with C-18 bonded silica which was packed into a column, elution with methylene chloride, and PTGC-NPD (HZS). Trichlorfon insecticide was extracted from soil and turfgrass, cleaned u by SPE, measured by GC-ECD, and confirmed by GUMS ( 5 2 9 ) . Chlorothalonil was determined by cellulose filter collection and HPLC-W for assessment of occupational exposure in eenhouse carnation culturing (H30). Chiral PT-HRGC&D/HRMS was used to determine low picogram levels of a-hexachlorocyclohexane enantiomers in environmental samples (H31).
(116). Dialkyl phosphate metabolites were determined in urine as pentafluorobenzylderivatives by GC-ECD for studies of human exposure to malathion (117). SpecificProcedures. The followi OP pesticide residue analyses were reported phosmet an? azinphos-methyl in apples by sonicationof whole fruit with methanol and analysis of the extract by (2-18HPLC-UV (118);profenfos in vegetable and fruit cro s b chloroform extraction, cleanup with charcoal, and 8-8 dPLC-UV (254 nm) (119);ethyl fenthion in tissues and organs of birds by methylene chloride/acetone (1:l)extraction, silica gelcolumncleanup, and GC-NPD (120); acephate and its principal metabolite, methamidophos, in treated leaves by ethyl acetate extraction,cleanup in a carbon minicolumn, and PTGC-NPD (121); separation of fenitrothion, ita oxy analog fenoxon, and the sulfones and sulfoxides of each by HPLC in a C-8 column with 50% aqueous acetone mobile phase (122); fenthion and ita oxidative metabolites from olive oil by conversion to their sulfones
ORGANOPHOSPHORUS PESTICIDES General Procedures. GC with packed and capillary columns and nitrogen/phosphorus thermionic, electron capture, flame photometric, and mass spectrometry detectors is the most common techni ue for OP pesticide residue determination. The use of H%LC with a UV detector set at a wavelength accordin to the particular pesticide to be determined and coupfed HPLC/MS is increasing rapidly. Microcolumn HPLC of some chiral OP pesticides was studied using Chiralcel OD packing and simultaneous UV and P-selective on-line thermionic detection (11). An XAD-2 resin was used for trace enrichment of diazinon, azinphosmethyl, and fenthion in an unsegmented flow solid-phase preconcentration system coupled on-line with HPLC-UV (220 nm) (12). A cholinesterase inhibition test was used to screen water for OP and carbamate pesticides preconcentrated by SPE (13). A flow in'ection system incorporatin an acetylcholinesterase sinde bead string reactor anC f pH electrode detector was describedfor determination of OP and carbamate pesticides (14). An enzyme sensor for OP and carbamate insecticideswas based on the coimmobilization and sequential enzymic reactions of acetylcholinesteraseand cholineoxidase (15). Postcolumn reaction HPLC detection of OPs and carbamates was also based on inhibition of immobilized acetylcholinesterase (16). ELISAs were developed for quantification of fenitrothion, chlorpyrifos-methyl,and pirimiphosmethyl in wheat grain and flour-milling fractions (17). Twent nine OP pesticides were simultaneouslydetermined in foods %y acetone extraction, methylene chloride/hexane (28) partition, and CGC-FPD (18). Paraoxon, methyl parathion, ethyl parathion, guthion, and fenitrothion were determined in fruits and tap and river water at sensitivity levels 2-10 times lower than EEC legal limits (19). Acetone or acetonitrile extraction, hexane artition, and coagulating cleanup with phosphoric acid an ammonium chloride was used for the simultaneous CGC-FPD determination of seven OPs in crops and fruits (110). A multiresidue method for OP insecticides in four rou s of foods involved extraction and cleanu methods taifore8to a particular food type and widebore C8C-FPD (111).A multiresidue screen for quantitative determination of 43 OP insecticides in 5 of plant and animal tissues included extraction withmethano /methylene chloride (1:9), cleanup by automated GPC with hexane/ethyl acetate (64) eluent and in-line silica gel minicolumns, and GC-FPD (112). A method for nine OPs in vegetables used acetonitrile extraction, cleanup on C-18 and diol cartridges and by li uid partitioning, and GC-NPD (113). C-18 SPE cartriiges effectively cleaned up acetonitrile extracts of 3-g samples of fats and oils for the determination of OP pesticides by GCFPD ( C I 4 ) . Screenin and identification of OP esticides in blood from patients sdferin from acute agricugural chemical toxicity were established t y HPLC/atmos heric pressure CIMS (115). Representativesof four groups of pesticides and carbamate pesticides were determined in blood, lung, and liver by HPLC
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f
8P
acetylcholinesterase (128);acephate in aqueous extracts of agricultural soils by C-18 HPLC-UV (215 nm) (129); dimethoate in chrysanthemums and soil by GC-NPD (130); and terbufos sulfoxide and ita hydration product by GUMS (131). The performance and specificities of mono- and polyclonal antibody-based assays for fenitrothion in grain were studied, and measured concentrations were compared with those obtained by GC (132).
CARBAMATE AND CARBAMOYL INSECTICIDES General Procedures. Since methyl carbamate insecticides have a tendency to decompose during GC, the main approach for their determination involves HPLC with an alkaline hydrolysis or photodegradation reaction to generate a primary amine, postcolumn derivatization, and fluorescence detection. The original fluorometric labeling HPLC procedure of Moye et al. was improved and applied to 26 carbamate residues (JI). Carbofu~an,chlorpropham,carbaryl, propoxur, pirimicarb, and oxamyl were assayed in soils by use of solvent extraction with an acetone-containing solvent or methanol, Florisil or aminopro yl-silica chromatographic cleanup, and HPLC with UV d i d e array detection (J2). A collaborative study was conducted for the determination of N-methylcarbamates and N-methylcarbamoyloximesin finished drinking water by direct aqueous injection HPLC with postcolumn derivatization (J3). A flow-thro h sensor for determination of carbofuran, propoxur, and car aryl based on retention of the corresponding dyes, formed by hydro1 sis and couplin to diazotized sulfanilic acid, on C-18 bon&d hase packe! in a flow cell was developed (54). The therm2 degradation of aminocarb, bendiocarb, carbaryl, and dioxacarb during use of different GC injection techniques was evaluated (J5). Atmospheric pressure ionization techniques were studied for the MS analysis of N-methylcarbamate pesticides (J6). PIEI, PICI, and NICI mass spectra of nine carbamate pesticides were presented, along with procedures for isolation of the carbamates from biolo 'cal samples by use of C-18 Sep-Pak cartridges with chloroErm eluent (J7). Specific Procedures. The following determinations of carbaryl were reported: with 1-naphthol in apples and strawberriesby combinedGC/fluorescence spectrometry (J8); in honeybees using GC-NPD with confirmation by formation of a chemicalderivative (59);with entachlorophenolin water by hexane extraction and G C / S d M S (JIO);withcarbofuran in water by direct derivative spectrometry (Jl1);and in pond water and serum by C-18 HPLC-UV (210 nm) (512). Studies of carbaryl extraction from rice, maize, peas, and sunflower seeds prior to chromatographic analysis showed that acetone and methanol were the best solventa (J13). Three GC columns were compared for the direct determination of carbofuran by GC-NPD, and 2% OV-1Olshowed the highest responseand correlation coefficient for cahbration graphs (514).Carbofuran residues were determined in rice
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paddy water using C-18 SPE and gradient elution HPLC-UV with a cyclohex 1 column (515)and in tomato by GC-NPD and C-18 HPL8-UV (280 nm) (516). Four methods were compared for analysis of aldicarb residues in citrus soil, leaves, and fruit, and GC-NPD was the best choice (517).Aldicarb and ita sulfoxide and sulfone were determined in soil and sugar beets by GC-AFID of ethyl acetate extracts (518) and in water at ppb levels using a magnetic particle-based solid-phase ELISA (519). Promecarb extracted with acetone from mixed cellulose ester air filters was determined by fluorogenic labeling with dansyl chloride (520). Occupational exposure to propoxur was assessed by determination of ita metabolite, 2-isopropoxyphenol, in urine by CGC and mass selective detection (521). Oxamyland methomyl were determined in fruit, leaves, insects, and water by a method involving isolation by matrix solid-phase dispersion and HPLC with a single-stage postcolumn derivatization reaction and fluorescence detection (522).
HERBICIDES AND PLANT GROWTH REGULATORS As usual, papers devoted to herbicide analytical methodology dominated the applications literature during the past two years. This is in line with estimates that herbicides represent 70-80’3 of the total amount of pesticides used on crops in developed countries. General Procedures. Immunoassays to detect and quantify herbicides in the environment were reviewed (K1). A general method for developing immunoassays for chloroacetanilide herbicides was described ( K 2 ) . The use of ion trap MS in E1 and CI modes for herbicide analysis was discussed (K3). Thiolcarbamate herbicides were determined in natural water by C-18 Sep-Pak SPE and HPLC with spectrophotometric detection (K4). Atrazine and acetanilide herbicides were determined in water by liquid/liquid microextraction and GC-NPD (K5). A modified quality control chart was applied in the monitoring of herbicides in drinking water at the le a1 German tolerance level of 0.1 kg/L ( K 6 ) . A variety of herkcides were determined in soils and water by C-18 HPLC with acetonitrileiwater gradient elution and UV detection a t 230 nm (K7). A collaborative study was reported for determination of 10 herbicides in drinkin water using preconcentration b SPE and analysis by GC-EeD, GC-NPD, GC/MS, RP-HPL6, or TLC (K8). An HPLC method was developed for the determination of herbicides in drinking water according to DIN (German Industrial Standard) regulations (K9). Herbicides were determined in estuarine waters by GUMS and HPLC-diode array UV with a twostep methylene chloride liquid/liquid extraction (KIO).Bacterial biosensors were evaluated by three laboratories for Herbicide residues were screening herbicides in water (K11). determined in soil in the presence of OC insecticides by acetonitrile extraction and GC-NPD (K12). Five dinitroaniline herbicides were determined in soil and water by HPLC (K13). The sugar beet herbicides chloridazon, metamitron, and phenmedipham were determined in soil by use of acetone extraction and (2-18 HPLC with methanoliwater mobile phase (K14). The following multiresidue determinations of chlorophenoxy acid and/or ester herbicides were reported four phenoxy acids and picloram from surface wipes at US. Army pest control sho s by methylationand GC-ECD (K15);12 henoxy acids and gentazon in drinking water by SPE a n i HPLC with diode array detection (K16, K17);phenoxy ester herbicides by GC-FID and by HPLC after h drolysis to the free acids (K18);phenoxy acids in water w i d similar weak acid herbicides by SPE and HPLC with diode array detection (K19);phenoxy acids in soil by simultaneous extraction/ methylation and GC (K20); henoxy acids and esters in soil and water by HPLC/partici beam MS (K21, K22); interlaborator comparison of thermospray and article beam H P L C / d for 10 phenoxy acid herbicides (K)23);phenoxy acids in drinking water by HPLC with on-line ion-pair extraction and fluorescence detection (K24);GC analysis of 19phenoxy acids with intrainjector formation of methyl esters (K25);and screening for phenox acids in groundwater by HPLC of 9-anthryldiazomethane dlerivatives and fluorescence detection (K26). Phenoxyacetic and phenoxypropionic acids 46R
ANALYTICAL CHEMISTRY, VOL. 65, NO. 12, JUNE 15, 1993
were determined in water by extraction with QAE Sephadex A-25 and PTGC-ECD as their 2,2,2-trifluoroethylesters (K27). Nine acidic herbicides were analyzed in water and soil by extraction, cleanup on a Florisil microcolumn, methylation with diazomethane, and CGC-ECD (K28). A trifluoroanilide derivitization method was described for the GC-ECD and GUMS determination of propionic acid herbicides in water (K29). A procedure for determination of 13acidic herbicides in water, including monochlorinated ones, involved acidification to pH
