SUPERCRITICAL-FLUID EXTRACTION OF PESTICIDES FROM VEGETABLES USING ANHYDROUS MAGNESIUM-SULFATE FOR SAMPLE PREPARATION

Supercritical fluid extraction (SFE) was evaluated for the extraction of imidacloprid, methiocarb, chlorpyrifos, chlorothalonil, endosulfan I, endosulfan II, and endosulfan sulfate from pepper and tomato, using vegetable sample:anhydrous magnesium sulfate (5:7) mixtures to carry out the extractions and HPLC/DAD, GC/ECD, and GC/FPD for analysis. Pre liminary experiments were performed to study the extractability of the se pesticides from glass wool and different water absorbent materials. Spiked tomato and pepper samples were extracted with supercritical ca rbon dioxide assessing different extraction conditional The chosen SFE conditions were 300 atm, 50 degrees C, 200 mu L of methanol static mo difier, 1 min static time, dynamic extraction with 15 mL of CO2, and c ollection in 3 mL of ethyl acetate. Except for imidacloprid, which was not recovered under any of the assessed conditions, pesticide recover ies were greater than 80%. Incurred residues of chlorpyrifos, endosulf an, and methiocarb in a number of pepper and tomato samples were as ef ficiently extracted with SFE as viiith conventional extraction methods .