GC-MS/MS Determination of Residual Amounts of 15 Pesticides in Water Samples with Low-Temperature Enrichment Liquid-Liquid Extraction

Based on the fact that pesticides reach a new mass transfer balance between the water and organic phases at freezing temperature, a novel sample enrichment method was established for simultaneous determination of 15 pesticides (organochlorine, organophosphorus and pyrethroid) in water combining gas chromatography-triple quadropole mass spectrometry with low temperature enrichment liquid-liquid extraction. The following conditions were optimized, the extraction solvents, freezing temperature and time: extraction solvent was toluene (2.0 mL), the freezing temperature was -40 ℃, and the freezing time was 1 h. The detection limits (3S/N) and lower limits of determination (10S/N) found were in the ranges of 0.005-0.02 μg·L-1 and 0.02-0.07 μg·L-1, respectively. The proposed method was applied to the analysis of water sample, giving values of recovery and RSD′s (n=5) in the ranges of 78.8%-124% and 0.9%-9.1%, respectively.