Accumulation kinetics and sampling rates for 56 polar organic compounds, identification and validation of 5 PRCs

communication par affiche; International audience; POCIS (Polar Organic Chemical Integrative Sampler) is a new emerging tool for sampling polar organic micropollutants in water. There is still a need of research concerning its domain of validity (e.g., molecules sampled, type of water studied, optimal exposure duration) and its performances (molecules sampling rates, repeatability, accuracy of the evaluation of time-weighted average or TWA concentrations). In order to obtain in situ TWA concentrations, POCIS needs to be calibrated in laboratory for each molecule of interest. We performed 3 different laboratory calibration experiments using a flow-through calibration system in order to evaluate the optimal exposure duration and to calculate the sampling rates for 56 polar organic contaminants, and to identify and validate performance reference compounds (PRCs). The calibration system was composed of 2 aquaria (50 L) containing i) spiked tap water (circa 3 μg/L) and non-spiked POCIS for the determination of accumulation kinetics, ii) non-spiked tap water and spiked POCIS for the determination of desorption kinetics and iii) spiked tap water and spiked POCIS for the validation of the potential PRCs. In all experiments, water temperature, pH, conductivity and dissolved organic carbon were controlled. Agitation in the aquaria was ensured via a submerged pump. The resulting flow velocity was 10±5 cm/s and was directed perpendicularly towards POCIS surface. Triplicate POCIS were analyzed at 0, 1, 3, 6 and 12 hours and at 1, 3, 7, 11, 14, 21 and 28 days. We present results for the 56 studied molecules, including the duration of linear accumulation phase, sampling rates and possible performance reference compounds (PRCs). The accumulation phase was curvilinear for almost all molecules; so, we obtained the duration of optimal linear accumulation phase using t1/2 criteria. Concerning the desorption experiments, 5 compounds showed a good potential as PRC; they enable to decrease the effect of variable environmental conditions, so they can be used to obtain more reliable in situ TWA concentrations. We also checked isotropic exchange for these molecules comparing the exchange constant ke in accumulation and desorption experiments. At last, we validated the PRC strategy by calculating TWA concentrations from the third laboratory experiment mentioned above.