Simple one-step extraction and cleanup by pressurized liquid extraction for gas chromatographic–mass spectrometric determination of pesticides in green leafy vegetables

A simple one-step extraction and cleanup using a pressurized liquid extraction method was developed for the gas chromatographic–mass spectrometric determination of pesticides in vegetables. The pressurized liquid extraction conditions were optimized and cleanup agents were evaluated. The investigated pesticides included six insecticides, chlorpyrifos methyl, pirimiphos-methyl, malathion, chlorpyrifos, O-ethyl O-4-nitrophenylphenyl phosphonothioate (EPN) and permethrins, a fungicide, isoprothiolane, and a herbicides, thiobencarb. The cleanup agent and a mixture of the vegetable and anhydrous sodium sulfate were separately packed in an extraction vessel. A transparent and colorless extract was obtained using graphitized carbon as the cleanup agent. The overall recoveries were 71–103% and the relative standard deviations ranged from 5.6 to 24%. The limit of detection values were 3–8 μg kg−1. This method was successfully applied to green leafy vegetables.