Determination of Volatile Chlorinated Hydrocarbons in Soil Using Sampling Vials for Storage and Extraction by Means of Water-hexane Extraction Method.

Abstract

For the investigation of the contamination mechanism of underground water with 1, 1, 1-trichloroethane (MC), trichloroethylene (TCE), tetrachloroethylene (PCE) and carbontetrachloride (CTC), it is necessary to determine them in the soil. Since these compounds are volatile, sample storage is difficult. Moreover, it is difficult to extract them, which were strongly adsorbed on the soil, with nonpolar organic solvents. An attempt was made to use the 100 ml vial with a metal sealed cap, as storage and extraction bottles, and the determination of the above contaminants were performed by the water-hexane extraction method. Soil samples were examined by this method according to the following procedures ; About 5 g of soil samples was weighed in the field. The sample was poured immediately into the vial, which had been added with about 40 ml of purified water beforehand. Then, more water was added to the level mark of 80 ml. The vial was sealed with a PTFE seal, silicone rubber septum and aluminum crimp cap. The vial was shaken for 15 min and kept at 5°C until use. For the examination, the cap of vial was opened, and 20 ml of n-hexane was added to the vial. After the top was sealed again, the vial was shaken vigorously in lateral direction for 30 min. The hexane extract was injected into a ECD-GC. CV in repeated examinations was within 10% and reproducibility was supported. As the results of trials, the use of vials for storage and extraction was indicated to be a simple, practical and satisfactory method.