Simplified method for the determination of chlorinated fungicides and insecticides in fruits by gas chromatography

A fast, reliable method fur the determination of more than twenty chlorinated fungicides and insecticides in a variety of fruit samples is presented. The pesticides are extracted from chopped samples with magnetic stirring, after adding 13 ml of acetone-phosphate buffer-brine solution (12:1, v/v) with 5 mi of n-hexane. The continuous module employed allows sequential decolourization of the organic phase, solvent changeover and solid-phase extraction for clean-up and preconcentration purposes. A 1-mu l aliquot of the pesticides in ethyl acetate (eluent) is finally injected into the gas chromatograph for separation and identification. The method provides excellent clean-up despite the complexity of the matrices involved. Fruit samples (5-20 g) containing 0.1-1250 ng/g pesticides were analysed with a high precision (4-6%). After contamination of the fruit samples for 12 h, average recoveries >90% at fortification levels of 5-25 ng/g were obtained for most of the pesticides. Positive findings of these pesticides in fruits purchased at local markets were confirmed by GC-MS. (C) 2000 Elsevier Science B.V. All rights reserved.