Polymer-water partition coefficients of butyl rubber and polydimethylsiloxane passive samplers for polycyclic aromatic hydrocarbons using the co-solvent method.

Polycyclic aromatic hydrocarbons (PAHs), as ubiquitous hydrophobic pollutants, pose serious risks to aquatic ecosystems and human health due to their bioaccumulation and toxicity. Polymer-water partition coefficients (Kpw) are crucial for calculating the freely dissolved concentrations of these pollutants in water during passive sampling. This study experimentally determined Kpw values for the novel butyl rubber passive samplers (BR) for the first time and also for the polydimethylsiloxane (PDMS) as a reference passive sampler using the co-solvent method with methanol as co-solvent for 15 PAHs. The determined log Kpw values for PDMS samplers ranged from 3.6 to 6.4, while single-network BR (SN10) and triple-network BR (TN) samplers showed narrower ranges of 3.0 to 4.6 and 3.0 to 3.7, respectively. First- and second-order regression analyses revealed that molecular weights better represent the partitioning behavior of PAHs rather than octanol-water partition coefficients. The second-order regression equations, with correlation coefficients (R2) from 0.83 to 0.98, facilitate the estimation of Kpw values for BR samplers for other organic pollutants and provide validation data for future model studies.