Determination of distribution constants between a liquid polymeric coatingand water by a solid phase microextraction technique with a flow-through standard water system

This paper describes an optimized experimental system for determining water /polymer coating distribution constants and discusses the mechanism of extr action of high molecular weight compounds by poly(dimethylsiloxane) (PDMS). The proposed flow-through standard water generator eliminates errors assoc iated with both losses of analytes to the system surfaces and limited sampl e volume. In addition, the errors caused by partial precipitation or poor d issolution of highly hydrophobic analytes during spiking of water when prod ucing calibration standards are also eliminated. The target analytes are a range of polycyclic aromatic hydrocarbons (PAHs). The results demonstrate t hat absorption partitioning is the predominant mechanism of extraction of a nalytes into PDMS-coated fibers for all PAHs investigated regardless of mol ecular weight. There is a strong correlation between determined PDMS/water distribution constants (K-fw) and literature K-ow values for all PAHs.