半透膜微萃取方法的建立及其在测定土壤间隙水中憎水性有机污染物的应用

提出了一种新型的基于半透膜被动采样技术的微萃取方法（semi-permeable membrane based micro-extraction, SPM-ME），并以菲为模型污染物，测试了SPM-ME用于测定土壤间隙水中自由溶解态憎水性有机污染物的可行性。结果表明，菲在该SPE-ME装置与水相间的平衡可在6 h内达到，并且随着装置中三油酸甘油酯含量的增加，单元SPE-ME对于菲的富集系数也相应增加。该装置对土壤间隙水中菲的富集在10 d内能达到平衡，整个过程主要受菲从土壤向间隙水的传质控制。该装置测得间隙水中菲的浓度与实际测得间隙水浓度十分吻合，而由传统的相平衡分配法计算所得间隙水浓度则高出实测值4-5倍。同时，该装置对体系中污染物的耗竭小于体系中污染物总量的1%。因此，SPE-ME是一种准确、有效、非耗竭式的微萃取技术。

Semi-permeable Membrane Based Micro-extraction Technique and Its Application in the Determination of Hydrophobic Organic Contaminants in Soil Pore-water

A novel semi-permeable membrane based micro-extraction technique （SPM-ME） was derived from semi-permeable membrane extraction technique, and its applicability in measuring the free dissolved concentration of hydrophohic organic contaminants in soil porewater was tested using phenanthrene as a model compound. The triolein was dissolved into chloroform and introduced into low-density polyethylene （PE） layflat tubing. After the evaporation of solvent （chloroform）, the tubing was heat sealed. Compared to the traditional SPME technique, smaller volume of triolein was added into tubing to minimize the depletion of the target compound by extraction device and to fulfill the limit for micro-extraction technique. The equilibration of phenanthrene between SPM-ME device and water phase could be achieved in 6 h, and the partitioning coefficients based on unit SPE-ME device increased with the increasing amount of triolein in the device. The equilibration of phenanthrene between SPM-ME and soil pore-water was achieved in 10 d, which was mainly controlled by the transfer of phenanthrene from soil to pore-water. Compared to the traditional partitioning model overestimating the concentration in soil pore-water by a factor of 4-5, the concentrations of phenanthrene in soil pore-water detected by SPM-ME were coincided with those determined directly in the soil pore-water. The depletion of phenanthrene by SPM-ME was less than 1% of the total mass in the system. Hence, SPM-ME is an accurate, effective and non-depletion micro-extraction technique.