Effect of sampler material on the uptake of PAHs into passive sampling devices

Increasing demand for simple and reliable passive samplers for monitoring hydrophobic organic contaminants in water has led to increased frequency of use of single-phase polymeric sampling devices. In this study, we evaluate the effect of sampler material on the passive sampling of polycyclic aromatic hydrocarbons (PAHs) in two Norwegian rivers. Low density polyethylene membranes (LDPE), silicone strips and semipermeable membrane devices (SPMDs) with the exact same surface area and conformation were exposed in the Drammen River for overlapping exposures of 24 and 51 d, under identical hydrodynamic conditions. Dissipation rates of performance reference compounds (PRCs) spiked in all samplers were consistent and demonstrated no significant differences in sampler-water analyte exchange kinetics between the two exposures. The transition to fully boundary layer-controlled uptake shown by PRC dissipation rates was confirmed by investigating PAH masses absorbed by the samplers. Masses of analytes with log K(ow)>4.5 absorbed into the samplers were similar and independent of the sampler material used, generally indicating for these compounds that the boundary layer dominated the resistance to mass transfer. The very low variability in analyte masses absorbed across sampler types observed here indicates that much of the overall variability in dissolved contaminant concentrations seen in passive sampler intercomparison studies is likely the result of the uncertainty associated with sampler-water partition coefficients and PRC dissipation rates. PRC dissipation rates and ratios of masses absorbed over 51 and 24 d for these compounds demonstrated integrative sampling over 51 d and no major effects of biofouling on sampling. The equivalence of data obtained using silicone strips and SPMDs supports the use of single-phase polymeric passive sampling devices.