Residues of cypermethrin in field-treated grapes and raisins produced after various treatments.

Residues of the synthetic pyrethroid insecticide cypermethrin in fresh grapes of cv. Thomson Seedless and in raisins were studied. The commercial formulation Cymbush10% EC was applied according to the label onto the typical seedless variety and on a seed-producing clone. Samples were collected at time zero and at 15 or 21 days post-application. The raisins were produced either by submersion for 3 min in an aqueous solution of 3% potassium carbonate and 1% ethyl oleate, and dried for 15 days under direct sunlight or were dried without chemical processing. A gas chromatographic method was used for the analysis of residues. The residues in the grapes at the recommended preharvest interval (15 days) ranged from 0.23 to 0.41 mg kg(-1), whereas those in raisins ranged from 0.25 to 0.46 mg kg(-1).