Abstract: A method for the simultaneous determination of captan and folpet pesticide residues in apples was developed by solid-phase extraction and high performance liquid chromatography. The sample was extracted with acetonitrile and cleaned-up by a mixture of homemade sorbent and silica gel with hexane-dichloromethane-acetonitrile (50∶49∶1, v/v) as the eluent. The cleaned effects by using Florisil column, amino column, the mixed sorbent were compared, and the effect of the mixed sorbent was the best. The optimal analytical conditions were follow as: an methanol-acetonitrile-water (50∶5∶45, v/v) containing 0.1 mmol/L acetic-acetate buffer (pH 3.80) as the mobile phase, detection at 210 nm. The method had a good linear relationship in the range of 0.40-8.00 mg/kg for captan and folpet (r＞0.9999). The detection limits of captan and folpet were 0.27 mg/kg and 0.20 mg/kg, respectively. The relative standard deviations (RSDs) of retention time were no more than 0.60%. The average recoveries of captan and folpet from the apples spiked at three levels ranged from 69.3%-106% and 101%-108%, with RSD of 3.7%-4.7% and 1.3%-5.4%, respectively.

Key words: apple , captan, folpet, high performance liquid chromatography (HPLC), homemade sorbent, mixed sorbent, silica gel, solid-phase extraction