Polyethylene-Water and Polydimethylsiloxane-Water Partition Coefficients for Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyls: Influence of Polymer Source and Proposed Best Available Values

Abstract

For most passive sampling applications, the availability of accurate passive sampler–water partition coefficients (Kp-w) is of key importance. Unfortunately, a huge variability exists in literature Kp-w values, in particular for hydrophobic chemicals such as polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). This variability is a major source of concern in the passive sampling community, which would benefit from high-quality Kp-w data. Hence, in the present study “best available” PAH and PCB Kp-w values are proposed for the two most often applied passive sampling materials, that is, low-density polyethylene and polydimethylsiloxane (PDMS), based on (1) a critical assessment of existing literature data, and (2) new Kp-w determinations for polyethylene and PDMS, with both polymers coming in six different versions (suppliers, thicknesses). The experimental results indicated that Kp-w values for PDMS are independent of the source, thus allowing straightforward standardization. In contrast, Kp-w values for polyethylene from different sources differed by up to 30%. Defining best available Kp-w values for this polymer therefore may require standardization of the polymer source. Application of the proposed best available Kp-w values will substantially improve the accuracy of freely dissolved concentration results by users and the potential for comparisons across laboratories. Environ Toxicol Chem 2022;41:1370–1380.