Multi-residue methodology for pesticide screening in wines

A multi-residue solid-phase microextraction/gas chromatography/electron-cap ture detection method for pesticide screening (nine organochlorine, eleven organophosphorous and a tiadiazine insecticides, a benzoylurea acaricide an d a halogenated sulfamide fungicide) in wine was developed. Fiber coating, extraction time and temperature, exposure of the fiber to the headspace or to the liquid phase and the ethanol effect on pesticides extraction were th e parameters studied. The best results were obtained for a 100 mu m Poly(di methylsiloxane) fiber, with 30 min immersion, in a 3 mi sample, at 45 degre es C. Pesticides extraction yield from aqueous spiked solutions was studied , for different ethanol concentrations (9%, 12.5% and 20%, v/v), which are representative of the main types of Portuguese wines. Calibration curves fo r extracted standards gave linear responses for all the pesticides, except dichlorvos, mevinphos, disulfoton and methidathion. Average detection Limit s were fewer than 5 ppb and no significant interference from the matrix was found in the conditions studied, except for buprofezin. (C) 2000 Elsevier Science B.V. All rights reserved.