Multiresidue analysis of 36 pesticides in soil using a modified quick, easy, cheap, effective, rugged, and safe method by liquid chromatography with tandem quadruple linear ion trap mass spectrometry

A new method for simultaneous determination of 36 pesticides, including 15 organophosphorus, six carbamate, and some other pesticides in soil was developed by liquid chromatography with tandem quadruple linear ion trap mass spectrometry. The extraction and clean-up steps were optimized based on the quick, easy, cheap, effective, rugged, and safe method. The data were acquired in multiple reaction monitoring mode combined with enhanced product ion to increase confidence of the analytical results. Validation experiments were performed in soil samples. The average recoveries of pesticides at four spiking levels (1, 5, 50, and 100 mu g/kg) ranged from 63 to 126% with relative standard deviation below 20%. The limits of detection of pesticides were 0.04-0.8 mu g/kg, and the limits of quantification were 0.1-2.6 mu g/kg. The correlation coefficients (r(2)) were higher than 0.990 in the linearity range of 0.5-200 mu g/L for most of the pesticides. The method allowed for the analysis of the target pesticides in the lower mu g/kg concentration range. The optimized method was then applied to the test of real soil samples obtained from several areas in China, confirming the feasibility of the method.