Applicability of polydimethylsiloxane (PDMS) and polyethersulfone (PES) as passive samplers of more hydrophobic...

The uptake calibration of three passive samplers, stir-bars, MESCO/stir-bars and polyethersulfone tubes (PES_t), was assessed in seawater at different salinities for 17 organic compounds including organochlorine compounds, pesticides, phthalates, musk fragrances and triclosan. The calibration procedure was accomplished by exposing the samplers to a continuous flow of fortified seawater for up to 14days under laboratory conditions. Prior to the exposure, stir-bars and MESCO/stir-bars were loaded with a known amount of deuterated PAH mixture as performance reference compounds (PRC). For most of the studied compounds, the sampling rates (Rs, mL·day^-1) were determined for each sampler at two salinities (15 and 30‰) and two nominal concentrations (25 and 50ng·L^-1). Among the tested devices, though PES can be an outstanding cheap alternative to other passive samplers, naked or free stir-bars provided the best results in terms of uptake rates (i.e., the Rs values ranged from 30 to 350mL·day^-1). Regarding the variation of the salinity, the Rs values obtained with naked stir-bars were statistically comparable in the full range of salinities (0-30‰) but the values obtained with MESCO/stir-bars and PES_t were salinity dependent. Consequently, only stir-bars assured the required robustness to be used as passive samplers in intertidal estuarine environments. Finally, the stir-bars were applied to estimate the time-weighted average concentration of some of those contaminants in the feeding seawater of the experimental aquaria at the Plentzia Marine Station (Basque Country) and low levels of musks fragrances (0.1-0.2ng·L^-1) were estimated.