An improved Chemcatcher-based method for the integrative passive sampling of 44 hydrophilic micropollutants in surface water - Part A: Calibration under four controlled hydrodynamic conditions.

When monitoring water quality with hydrophilic integrative passive sampling devices, it is crucial to use accurate sampling rates (R) that account for exposure conditions such as hydrodynamics. This study aims at calibrating Chemcatcher-like passive samplers - styrene-divinylbenzene reverse phase sulfonate (SDB-RPS) extraction disk covered by a polyethersulfone (PES) membrane - at four water flow velocities (5 to 40 cm s) in a channel system. First, the four hydrodynamic conditions were characterized by measuring the mass transfer coefficients of the water boundary layer (k) at the surface of the samplers using the alabaster dissolution method. Then, fifty-six samplers were deployed in the channels and exposed for 7 different intervals varying from 1 to 21 days. Thus, R were determined at four different k for 44 hydrophilic compounds, ranging from 0.015 to 0.115 L day. Relationships were established between k and R using models for mixed rate control by the membrane and the water boundary layer. The estimated parameters of those relationships are suitable for the determination of accurate R when k is measured in situ, for example by co-deploying silicone disks spiked with performance and reference compounds (PRC) as implemented in Part B.