Matrix solid-phase dispersion extraction of organophosphorus and synthetic pyrethroid pesticides in cashew nut and passion fruit

Abstract

A multiresidue extraction method based on matrix solid-phase dispersion (MSPD) and capillary gas chromatography–electron capture detection for quantification of five widely used organophosphorus insecticides (diazinon, malathion, parathion, methidathion, and pyrazophos) and one synthetic pyrethroid (permethrin) in Brazilian fruits is described. Cashew nut and passion fruit are plants native to South America. Capillary gas chromatography with mass selective detection was also utilized to confirm the pesticides through mass spectra. Different parameters were optimized, such as the solid phase and dispersant used, amounts, type of eluant and volume, and sample amount. The best results were obtained using a silica gel cartridge column and Florisil as dispersant. The eluant was ethyl acetate. Analysis of fortified fruit (n=3) shows an average recovery of 101.4% for cashew nut and 97.8% for passion fruit at 0.3–1.0-mg/kg levels. Detection limits ranged from 0.2 to 0.4 pg for the compounds studied using 1-g samples. The linearity, repeatability, and recoveries of the method are presented. This MSPD method was compared with solid-phase extraction (SPE) for cleanup, using an alumina–silica gel (1 : 1) cartridge column and ethyl acetate as eluant. Analysis of fortified fruit (n=3) shows an average recovery of 104.9% for cashew nut and 106.8% for passion fruit at 0.1–0.6-mg/kg levels. Detection limits ranged from 0.2 to 0.6 pg for the compounds studied using 25-g samples. The combined use of C18 and silica (or Florisil) makes this extraction system unsuitable for these fruits matrixes. The cleanest extracts are obtained using two polar (Florisil and silica) solid phases. In conclusion, the proposed MSPD method described here can be applied to extract five organophosphorus pesticides and permethrin in 1 g of fruit. It is advantageous because it uses ethyl acetate as the only solvent, is faster and uses less solvent than SPE methods, and requires only small sample sizes. ©1999 John Wiley & Sons, Inc. J Micro Sep 11: 367–375, 1999