A rapid, multiresidue procedure utilizing the minimal cleanup necessary for gas-liquid chromatographic (GLC) analysis is presented. The samples are extracted with acetone and partitioned with methylene chloride-petroleum ether to remove water. The organophosphorus and organonitrogen compounds are then quantitated by GLC, using a KCI thermionic detector. A Florisil cleanup of the extract is performed prior to the determination of organochlorine compounds by a GLC electron capture detector. Carbon-hydrogen compounds such as biphenyl and o-phenylphenol undergo the Florisil cleanup and may also be quantitated by GLC. Quantitative recoveries for 15 organophosphorus, 9 organochlorine, 5 organonitrogen, and 2 hydrocarbon pesticides show the range in polarities of pesticides recovered, from Monitor to biphenyl. The method is simple and fast with a great potential for the analysis of many more compounds.

The multiresidue procedure of Luke et al., which uses extraction with acetone and partition with petroleum ether and methylene chloride, was simplified and shortened by eliminating the Florisil cleanup. Double concentration with petroleum ether in the Kuderna-Danish evaporator following the initial concentration removed the last traces of methylene chloride. The extract was then injected into a gas chromatograph, using a Hall electrolytic conductivity detector for organohalogen, organonitrogen, and organosulfur pesticides or a flame photometric detector for organophosphorus pesticides. Recoveries of 79 pesticides are presented.

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Previous studies using the ion trap as a potential replacement for an array of element-sensitive detectors indicated that only semi-quantitative results at the 50-100 ppb range could be obtained for 245 pesticides because of interfering endogenous sample matrix compounds. The development of a new clean-up procedure for a wide range of fruits and vegetables, specifically for use in an ion trap, has been undertaken to improve recoveries at the low ppm level to within analytically acceptable ranges (80-120%). This clean-up involved the use of three solid-phase extractions. The use of a C-18 SepPak column removed the majority of hydrocarbon-like molecules while the anion-exchange column (QMA) removed all colored compounds and flavors, and finally the use of an aminopropyl column removed all sugars. Preliminary results from this study using 24 selected pesticides in four different sample matrices have indicated an acceptable improvement over previous results.