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-CLPⅡcolumn and the Rtx- 1701 column) was adopted for identification of the OCP's by comparing values of t_R with reference materials,and quantification of the OCP's was performed by using the Rtx-CLPⅡcolumn 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 1-80μg·L~(-1),with detection limits(3s/k) in the range of 1.5-5.6μg·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%.