Characterization of the Permeation Properties of Membrane Filters and Sorption Properties of Sorbents Used for Polar Organic Chemical Integrative Samplers

Polar organic chemical integrative samplers (POCIS) are promising devices for measuring time-weighted average concentrations of hydrophilic compounds in aquatic environments. However, the mechanism of POCIS uptake remains unclear. This study characterizes the permeation properties of polyethersulfone and polytetrafluoroethylene and the sorption properties of Oasis HLB (Waters), Envi-Carb (Supelco), and Oasis WAX (Waters) under identical conditions via calibration experiments of the POCIS. Plant protection products, neonicotinoid herbicides, and linear alkyl benzene sulfonates (LAS) were tested. The permeation experimental results suggested that the penetration rate constants (k_m) with high K_ow values (K_ow: octanol–water partition coefficient) were low, which indicated that the sorption of chemicals on the membrane may constitute a limiting factor for the permeation. The sorption experiments indicated that the sorption rate constants (k_s) depended on the type of sorbent instead of the K_ow values. Low k_s/k_m ratios were obtained for chemicals with low K_ow values, which implied that the POCIS uptake for highly hydrophilic compounds was controlled by both membrane and sorbent kinetics. The k_m and k_s values corresponded to the model and predicted the values of the sampling rates (R_s) for the LAS. These findings revealed the possibility of using k_s and k_m values to predict R_s values.