A rapid multi-residue method for simultaneous analysis of 185 pesticides in upland and paddy soil by GC-MS/MS was developed. For the sample preparation, the pesticide was extracted with acetonitrile containing 0.1% acetic acid, treated with magnesium sulfate and sodium chloride, and then the extract was centrifuged, without dispersive SPE procedures, before analysis by GC-MS/MS with SRM (selected reaction monitoring) mode. For SRM of the best specificity, two different precursor ions per compound were selected to produce product ion from each precursor on collision-induced dissociation optimization. Limit of detection was improved significantly by pressure pulsed injection (2 uL, 40 psi) compare to conventional injection in GC. Quantitation was performed using matrix matched calibration curves at concentration ranging from 0.002 mg kg-1 to 0.2 mg kg-1. Correlation coefficients (R2) of calibration curves was >0.99 for all target compounds. Limit of quantitation were in the range of 0.001-0.050 mg kg-1. To evaluate validity of the method, recovery tests were carried out with soil at spiking levels 0.01 and 0.05 mg kg-1. The accuracy and precision results satisfied 70-120% (RSD =20%) for 95.0 %(upland soil) and 88.5 % (paddy soil) of the 185 pesticides at fortification level 0.01 mg kg-1. At higher fortification level of 0.05 mg kg-1, 96.5% (upland soil) and 90.5% (paddy soil) of 185 pesticides were in the range of 70-120% (RSD =20%). The established method was applied to 9 different samples of soil from pesticides treated areas to detect 7 pesticides. As a result, the present method was proved to be efficient and rapid in multi-residue analysis of soil.

Simultaneous analysis of 185 pesticide residues in upland soil and paddy soil by GC-MS/MS

248th National Meeting (2014)

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