GC-MS Determination of Residual Amounts of 19 Pesticides in Drinking Water with Enrichment by Liquid-Liquid Extraction

GC-MS with enrichment by liquid-liquid extraction was applied to the determination of residual amounts of 19 pesticides in drinking water. The pesticides in sample were extracted thrice with dichloromethane (20, 10, 10 mL), the extracts were combined and evaporated rotationally to 1.0 mL, from which 1.0 μL was taken for GC-MS analysis. The HP-5MS capillary column was used for separation, and EI source with SIM mode was used in MS determination. Phenanthrene-d10 was added as internal standard, and values of peak area were used in quantification. Linearities for the 19 pesticides were obtained in definite concentration ranges, with values of detection limits (3S/N) ranged from 0.002 to 0.10 mg·L-1. Values of recovery found by standard addition method were in the range of 81.1%-103.0% with RSD′s (n=6) ranged from 0.25% to 7.7%.