An Accelerated Solvent Extraction-Solid Phase Extraction-Gas Chromatography/Mass Spectrometry Method for Determination of 18 Pesticides in Paddy

A gas chromatography/mass spectrometry(GC/MS) method was established for the determination of 18 pesticides in paddy based on the accelerated solvent extraction (ASE) method:in the 30 mL extraction pool under a pressure of 10.34 MPa, heating for 5 min at 80℃, and static extracting with acetonitrile for 3 min, cycling for 2 times, then washing the extraction pool with acetonitrile of 60% of the pool volume, then purging for 100 s with nitrogen. And then a solid phase extraction (SPE) column with an extraction rate of 1 drop/second was used for the purification of sample. In this method, the samples were first extracted with acetonitrile, and then purified by SPE column and evaporated to dryness in a rotary evaporator. The pretreated samples were re-dissolved in n-hexane to a constant volume for the determination by GC/MS. Linear relationships between values of peak area and mass concentration of 18 pesticides were found in the range of 0.05~1.0 μg/mL, all of their linear correlation coefficients were more than 0.99. The limits of detection were 0.104~0.647 mg/kg, and the minimum quantitative limits were 0.276~1.724 mg/kg. The spiked recoveries were between 82.5%~105.1%, and the RSDs were between 1.5%~6.4%. The method is suitable for the determination of 18 pesticides in paddy.