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. Preliminary experiments were performed to study the extractability of these pesticides from glass wool and different water absorbent materials. Spiked tomato and pepper samples were extracted with supercritical carbon dioxide assessing different extraction conditional The chosen SFE conditions were 300 atm, 50 degrees C, 200 mu L of methanol static modifier, 1 min static time, dynamic extraction with 15 mL of CO2, and collection in 3 mL of ethyl acetate. Except for imidacloprid, which was not recovered under any of the assessed conditions, pesticide recoveries were greater than 80%. Incurred residues of chlorpyrifos, endosulfan, and methiocarb in a number of pepper and tomato samples were as efficiently extracted with SFE as viiith conventional extraction methods.