Study on Enrichment of Semi-Volatile Organic Pollutants from Ground Water Samples Collected at Non-Fixed Experimental Sites by Adsorption on SPE Membranes, and Its Time of Preservation and Mode of Transportation under Stable State

C₁₈ membranes with silica gel as adsortent were selected to be carriers for enrichment of semi-volatile organic pollutants from sample of ground-water (1.0 L) at a flow-rate of 100 mL·min^-1. 19 Compounds, including organochlorine pesticides, polycyclic aromatic hydrocarbons, poly-chlorinated biphenyls and phthalates were tested. The C₁₈ membrane with the adsorbates was transferred to and sealed in a 10 mL brown glass bottle, and the adsorbates on the membrane could be kept stable for 30 days at temperatures below 6℃, and transported under this condition. The adsorbates were eluted ultrasonically from the C₁₈ membrane with 2.0 mL of n-hexane at ca. 25℃ for 10 min, and 0.50 mL of the eluate was taken and used for GC-MS analysis. Several groups of ground water samples taken from various areas in our country were analyzed by the proposed method and 3 samples were selected to be used as matrixes in tests for recovery by standard addition at 3 concentration levels, the results of recovery found were in the range of 75% to 112%. Seven samples with addition of 0.020 μg·L^-1 of the substitute standard in each sample were analyzed by the proposed method, giving values of RSDs (n=7) in the range of 4.9% to 13%. By using the conditions given in this method, the time of presevation of the adsorbates on the C₁₈ membrane in their stable states were extended to 30 days, which was not only advantageous for storage and transportation of the analytes, but also facilitative for long-term field scientific works.