Development of a multi-residue method for 58 pesticides in soil using QuEChERS and gas chromatography-tandem mass spectrometry

This study developed a method for simultaneous determination of 58 pesticides in soil including those from organochlorine, organophosphorus, pyrethroid, carbamate and triazole classes and others commonly used in agricultural practice. The procedure was based on the quick, easy, cheap, effective, rugged and safe (QuEChERS) sample preparation method. The choice of the buffer, type of extract solvent, shaking time and dispersive solid phase extraction (d-SPE) clean-up were optimized. The analysis was performed using gas chromatography-tandem mass spectrometry (GC-MS/MS). Validation experiments were performed in spiked soil samples. The average recoveries at 5 mu g kg(-1) and 50 mu g kg(-1) spiking levels ranged from 69% to 119% with a relative standard deviation (RSD) below 20%. The method limit of quantification (LOQ) ranged from 0.1 mu g kg(-1) to 5 mu g kg(-1). The correlation coefficients (R-2) were higher than 0.9961 in the linearity range of 0.25-500 mu g kg(-1) for all the pesticides. The optimized method was then applied to test real soil samples collected from three regions in China, demonstrating the feasibility of the method.