GC Determination of 22 Organochlorine Pesticides in Water with Pretreatment of Samples by Liquid-liquid Extraction

Gas chromatography with electron capture detector was applied to simultaneous determination of 22 organochlorine pesticides (OCP′s) in water.OCP′s was separated and enriched from the water sample by extraction with n-hexane.The extract was concentrated and diluted to 1.0 mL with n-hexane.The double capillary chromatographic column practice,i.e.use of 2 columns of different polarity (the Rtx-CLP Ⅱ column and the Rtx-1701 column) was adopted for identification of the OCP′s by comparing values of tR with reference materials,and quantification of the OCP′s was performed by using the Rtx-CLP Ⅱ column with external standard method.Linear relationships between values of peak area and mass concentration of the 22 OCP′s were found same in the range of 1-80 μg·L-1,with detection limits (3s/k) in the range of 1.5-5.6 μg·L-1.Recovery of the method was tested,giving values of average recovery ranged from 73.3% to 107.9% and RSD′s (n=7) ranged from 2.9% to 14.8%.