GC Determination of OCP′s and PCB′s in Polluted Soil with Dual Chromatographic Columns and Dual ECD

GC with dual capillary columns and dual ECD was applied to the determination of 23 OCP′s and 7 groups of aroclor in polluted soil. 20 g of soil sample were extracted ultrasonically thrice with CH2Cl2, and extracts were concentrated at 40 ℃ by N2blowing and converted into nhexane solution with its volume concentrated to 1 mL. The concentrate was purified by conc. H2SO4 (for detn. of aroclor only), or by florisil column or silica gel column (for detn. of OCP′s only). For determination of both aroclor and OCP′s, the concentrate was purified by stepwise elution with silica gel column. Macromolecular impurities were removed by GPC. The purified solution, after concentrating to 1 mL, was used for GC analysis. Identification of OCP′s was made by referring to the retention time of the referential standards on the columns and quantification was made by external standard method. Qualification of aroclor was made by fitting with the spectra of primary standards and quantification was made on the base of average values of the calibration peaks (3-5 peaks should be chosen in the test). Detection limits found for OCP′s and aroclor were 0.001 mg·kg-1, 0.002 5-0.005 mg·kg-1 respectively, and values of av. recovery found were in the ranges of 82.1%-103% (for OCP′s) and 83.5%-94.7% (for aroclor).