Uptake and release of polar compounds in SDB-RPS Empore™ disks; implications for their use as passive samplers

Demand for sensitive monitoring tools to detect trace levels of pollutants in aquatic environments has led to investigation of sorbents to complement the suite of passive sampling phases currently in use. Styrenedivinylbenzene-reverse phase sulfonated (SDB-RPS) sorbents have a high affinity for polar organic compounds such as herbicides. However, the applicability of the performance reference compound (PRC) concept as an in situ calibration method for passive samplers that use this or similar sampling phases has yet to be validated. In this study, laboratory based calibration experiments were conducted to compare the uptake kinetics of several key pesticides with the release of three pre-loaded PRCs in Chemcatchers™ using SDB-RPS Empore™ disks deployed with a membrane and without (naked). For compounds with log KOW values ranging from 1.8 to 4.0, uptake into samplers with a membrane and without was linear over 30 d and 10 d, respectively. While uptake was linear and reproducible, PRC loss was not linear, meaning that the dissipation rates of these PRCs cannot be used to estimate field exposure conditions on uptake rates. An alternative in situ calibration technique using PRC loaded polydimethylsiloxane (PDMS) disks deployed alongside the Empore™ disk samplers as a surrogate calibration phase has been tested in the current study and shows promise for future applications.