Polymer-Water Partition Coefficients of Hydrophobic Compounds for Passive Sampling: Application of Cosolvent Models for Validation

摘要

Polymer-water partition coefficients (K_(pw)) of hexachlorobenzene, 41 polychlorinated biphenyls (PCBs), and 26 polyaromatic hydrocarbons (PAHs) were determined for low-density polyethylene (LDPE) and five different silicone rubbers. Partition coefficients were determined in ultra pure water and in a range of methanol-water mixtures. Different cosolvent models for the effect of methanol concentration on the polymer-mixture partition coefficient (K_(pm)) were used to validate the K_(pw) in pure water. Linear regression of IogK_(pm) against the mole fraction (x) methanol over range 0 < x < 0.3 yielded the best results. The obtained logK_(pw)s were best described by a correlation with molecular weight for PCBs in combination with the fraction of chlorine atoms in the meta and para positions (standard deviations of ～0.08 log units). Correlations with log K_(ow) were less good (standard deviations of ～0.21 log units), partly as a result of uncertainties in the log K_(ow) estimates that were used. Similar K_(pw)s were found for different batches of silicone rubber from the same supplier. Differences in logK_(pw)s for silicone rubbers obtained from different suppliers ranged from 0.16-0.58.