Evaluation of poly(ethylene-co-vinyl acetate-co-carbon monoxide) and polydimethylsiloxane for equilibrium sampling of polar organic contaminants in water.

The aim of the present study was to develop a passive absorptive equilibrium sampler that would enable the determination of the concentrations of polar organic compound (POC) in water more efficiently than existing techniques. To this end, a novel plastic material, poly(ethylene-co-vinyl acetate-co-carbon monoxide) (PEVAC), was evaluated and the results were compared with an existing silicone-based passive absorptive equilibrium device. Seven compounds (imidacloprid, carbendazim, metoprolol, atrazin, carbamazepine, diazinon, and chlorpyrifos), a mixture of pharmaceuticals, and pesticides with a logarithmic octanol-water partition coefficient ranging from 0.2 to 4.77 were selected as model substances for the experiments. The results showed that six of the seven selected POCs reached distribution equilibrium within 4 d in the two materials tested. A linear relation with a regression coefficient of more than 0.8906 between the established logarithmic absorbent-water partition coefficient and the calculated logarithmic dissociation partition coefficient of the selected compounds in the two polymers was observed. The correlation between these two coefficients was within one order of magnitude for the compounds that reached equilibrium in the two polymers, which demonstrates that both materials are suitable for mimicking biological uptake of POCs. The PEVAC material showed an enhanced sorption for all selected compounds compared to the silicone material and up to five times higher enrichment for the most polar compound. Fluorescence analysis of the sampler cross-section, following the uptake of fluoranthene, and proof that the sorption was independent of surface area variations demonstrated that the PEVAC polymer possessed absorptive rather than adsorptive enrichment of organic compounds.

The ability of a novel sorptive polymer to determine the freely dissolved fraction of polar organic compounds in the presence of fulvic acid or sediment.

A novel plastic material, poly(ethylene-co-vinyl acetate-co-carbon monoxide) (PEVAC), was evaluated as an absorptive passive equilibrium sampler for determination of the freely dissolved fraction of seven polar organic contaminants (POCs) in the presence of fulvic acid and sediment. The seven compounds selected were imidacloprid, carbendazim, metoprolol, atrazin, carbamazepine, diazinon and chlorpyrifos, i.e. a mixture of pharmaceuticals and pesticides having logarithmic octanol/water partition coefficients (log K(OW)) ranging from 0.2 to 4.77. The experiments demonstrated that the PEVAC sampler is well suited for determination of the freely dissolved fraction of chemicals in aquatic environments. Generally, the freely dissolved fraction of the POCs decreased with increasing hydrophobicity. However, strong interactions with functional groups of the organic matter seemed to dominate the partitioning for imidacloprid and carbendazim, having logarithmic dissociation partition coefficient log D < 1.47, and for metoprolol, which is positively charged at neutral pH.