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

A multiresidue extraction method based on matrix solid-phase dispersion (MS PD) and capillary gas chromatography-electron capture detection for quantif ication of five widely used organophosphorus insecticides (diazinon, malath ion, 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 ma ss spectra. Different parameters were optimized, such as the solid phase an d dispersant used, amounts, type of eluant and volume, and sample amount. T he best results were obtained using a silica gel cartridge column and Flori sil as dispersant. The eluant was ethyl acetate. Analysis of fortified frui t (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 l-g samples. The linearity, repeatab ility, and recoveries of the method are presented. This MSPD method was com pared with solid-phase extraction (SPE) for cleanup, using an alumina-silic a gel (1:1) cartridge column and ethyl acetate as eluant. Analysis of forti fied fruit (n = 3) shows an average recovery of 104.9% for cashew nut and 1 06.8% for passion fruit at 0.1-0.6-mg/kg levels. Detection limits ranged fr om 0.2 to 0.6 pg for the compounds studied using 25-g samples. The combined use of C-18 and silica (or Florisil) makes this extraction system unsuitab le 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 pesti cides and permethrin in 1 g of fruit. It is advantageous because it uses et hyl acetate as the only solvent, is faster and uses less solvent than SPE m ethods, and requires only small sample sizes. (C) 1999 John Wiley & Sons, I nc.