Determination of 7 Common Pesticides Residues in Soil by Gas Chromatography-Tandem Mass Spectrometry Coupled with Accelerated Solvent Extraction and Gel Permeation Chromatography Purification

A method of gas chromatography tandem mass spectrometry (GC-MS/MS) coupled with accelerated solvent extraction (ASE) and gel permeation chromatography (GPC) purification for the determination of 7 pesticides (quintozene, paclobutrazol, procymidone, metalaxyl, ethofenprox, acetamiprid and prochloraz) residues in soil was established. Soil samples were randomly collected and passed by 2 mm sieve after drying at 35 ℃and crushing. Screened soil sample of 10 g was placed in the accelerated solvent extraction tank, and extracted repeatedly 3 times by ASE with extraction solvent of a mixture of acetone and hexane at volume ratio of 1∶1. The extracted solution was purified by GPC and blown to nearly dryness by nitrogen. The residue was dissolved by hexane of 1 mL and filtered by 0.45 μm microporous membrane, then MRM mode was adopted in GC-MS/MS analysis, and external standard was used for quantification. As found by results, linearity relationships between mass concentrations of 7 pesticides and their peak areas were kept in the range of 0.04-4.0 mg·L^-1, with detection limits (3S/N) in the range of 0.002-0.007 mg·kg^-1. Recovery test was made on blank samples at 3 concentration levels, giving recovery of 7 pesticides in the range of 88.9%-104%, and RSDs (n=6) of the determined values less than 4.0%. The method was used for the analysis of actual samples, and promolide and acetamiprid were detected, with detection amounts of 0.010, 0.005 mg·kg^-1, respectively.