Determination of polyoxymethylene (POM)--water partition coefficients for oxy-PAHs and PAHs.

Oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs) are a class of ubiquitously occurring pollutants of which little is known. They can be co-emitted with PAHs or formed from PAHs in the environment. The environmental fate and risk of oxy-PAHs are difficult to assess due to a lack of methods to quantify their pore water concentrations. One sampler that can be used to determine freely dissolved concentrations of organic contaminants is polyoxymethylene (POM). In this study, POM - water partition coefficients (KPOM) were determined for 11 oxy-PAHs. KPOM values of 8 PAHs with similar hydrophobicities as the oxy-PAHs were determined for comparison. Results showed that logKPOM values ranged from 2.64 to 4.82 for the PAHs (2-4 rings), similar to previously determined values. LogKPOM values for investigated oxy-PAHs ranged from 0.96 to 5.36. The addition of carbonylic oxygen on a parent PAH generally lowered KPOM by 0.5 to 1.0 log units, which is attributable to the presence of carbonylic oxygens increasing water solubility. The KPOM values presented here will facilitate simultaneous assessments of freely dissolved water concentrations of oxy-PAHs and PAHs in environmental media.