Determination of 31 Organochlorine Pesticides in Water by SPE-Online GPC-GC-MS/MS

A method was developed for the determination of 31 OCPs in water by SPE-online GPC-GC-MS/MS, and applied to the analysis of water samples from different regions in Fujian province. Water sample was introduced into SPE column at the rate of 10 mL·min^-1, then the column was blown for 10 min with nitrogen to remove the water. Then 5 mL of dichloromethane was used to elute analytes at the rate of 1.0 mL·min^-1. Sample bottles were drained overnight, and washed twice with 5 mL of dichloromethane. The washing solution was combined with the eluate, then the mixture was blown to 0.5 mL with nitrogen, purified by online GPC and analyzed with GC-MS/MS. In online GPC analysis, GLNpak EV-200 column and mixed solvent composed of acetone and cyclohexane with volume ratio of 3:7 were used. In GC analysis, SH-Rxi-5Sil MS capillary chromatographic column was used as stationary phase under temperature programmed condition. In MS/MS analysis, EI was used to deionize and MRM mode was used to detect. Working curves were made by using matrix matching mixed standard solution series, and external standard method was used for quantification. Linearity relationships between mass concentrations of 31 OCPs and their respective peak areas were all kept in definite ranges, with detection limits in the range of 0.3-8.3 ng·L^-1. The spiked recovery test was made on actual water samples at 3 concentration levels, giving recoveries in the range of 67.0%-123%, and RSDs (n=6) of determined values ranged from 3.9% to 20%. The proposed method was used in analyzing water samples (including sea water, surface water and industrial wastewater) during the dry season from 11 regions of Fujian province, and the results showed that the detected amount of OCPs in water body was in the range of 5.2-125.6 ng·L^-1, and more OCPs (11 species) were detected in the seawater of Sandu'ao in Ningde. The detected amount of OCPs was lower than the previous data in Fujian Province, all lower than the limit specified by the standards from ching or authoritative organization.