MULTI-RESIDUE MATRIX SOLID-PHASE DISPERSION METHOD FOR THE DETERMINATION OF 6 SYNTHETIC PYRETHROIDS IN VEGETABLES FOLLOWED BY GAS-CHROMATOGRAPHY WITH ELECTRON-CAPTURE DETECTION

An effective multi-residue matrix solid-phase dispersion (MSPD) extraction and gas chromatographic-electron-capture detection method for the determination of six synthetic pyrethroids (fenpropathrin, cyhalothrin, permethrin, cypermethrin, fenvalerate and deltamethrin) in 5 g of vegetables (West Indian gherkin, eggplant, pak-choi, cabbage and garden peas) is described. The method uses a Florisil-based MPSD column for direct in-line clean-up with n-hexane-acetone (9:1). Recoveries calculated at 0.1 and 0.5 mu g/g fortification levels were between 92 and 113%. The method detection limits were between 5.1 and 91.5 ng/g. The method compared favourably with the traditional method in terms of the sample size, analysis time and overall cost. The method may serve as a screening protocol for the determination of pyrethroids in vegetables.