Critical Review of Low-Density Polyethylene's Partitioning and Diffusion Coefficients for Trace Organic Contaminants and Implications for Its Use As a Passive Sampler

Polyethylene (PE)-water equilibrium partitioning constants, K-PEw, were reviewed for trace hydrophobic organic contaminants (HOCs). Relative standard deviations were <30% for phenanthrene, anthracene, fluoranthene, and pyrene implying excellent reproducibility of K-PEw across laboratories and PE sources. Averaged K-PEw values of various HOCs were best correlated with aqueous solubility, logC(w)(sat)(L): logK(PEw) = -0.99(+/- 0.029)logC(w)(sat)(L) + 2.39(+/- 0.096) (r(2) = 0.92, SE = 0.35, n = 100). For 80% of analytes, this equation predicted logK(PEw) within a factor of 2. A first-order estimation of K-PEw can be obtained assuming constant solubility of the compounds in the PE, such that the variation in C-w(sat)(L) determines the differences in K-PEw. For PE samplers, K-PEw values do not change with the thickness of the PE sampler. The influence of temperature on K-PEw seems dominated by solubility-changes of the compound in water, not in PE. The effect of salt is rather well understood, using a Schetschenow-style approach. The air-PE partitioning constant; K-PEa, can be approximated as the ratio of K-PEw/K-aw (the air water partitioning constant). A critical review of diffusivities in PE, D-PE, suggests that best results are obtained when using the film-stacking method. A good correlation is then found between D-PE and molar volume, V-m (angstrom(3)/mol): logD(PE) (m(2)/s) = 0.0145(+/- 0.001)V-m + 10.1(+/- 0.20) (r(2) = 0.76, SE = 0.24, n = 74).