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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Gas chromatography/mass spectrometry techniques uslng chemlcal lonlratlon and electron Impact have been employed to conflrm the presence of ethylene dlbromlde In frults and gralns determlned by electron capture detection gas chromatrography. Interferences from both the solvent and coextractables have been mlnlmlzed to permlt a determlnatlon uslng only two Ions detected In the correct experlmental lntenslty ratlo belonging to the monobromoethylene carbonlum fragment Ion. A complementary measurement under negative Ion methane chemlcal lonlratlon has determlned the bromide Ion to be present.