A POCIS-based approach for the monitoring of pharmaceuticals in wastewater treatment plants: Calibration and deployment challenges

The impact of pharmaceuticals in aquatic environments requires complementary monitoring techniques to the more conventional grab sampling approach for an improved sample representativity. This study explores the application of Polar Organic Chemical Integrative Samplers (POCIS) in the analysis of a wide range of pharmaceutical residues in wastewater effluent, highlighting its advantages over grab sampling. Passive sampling techniques, extending sampling duration several days or weeks, provide continuous and representative data, improving the punctual nature of grab sampling. Despite their advantages, achieving quantitative results remains a challenge. Calibration through precise determination of sampling rates (R_S) is recommended to convert the accumulated contaminant mass on the adsorbent to water concentrations. In the present work, 78 pharmaceuticals were preselected for stability suitability for POCIS passive sampling. R_S were experimentally determined for 49 stable compounds: 33 of them had not been previously reported and most the other 16 agree with previous published literature. These R_S were used to determine the concentration of pharmaceuticals in a wastewater treatment plant (WWTP) near to Barcelona, Spain over 3 weeks. High concentrations of 1,7-dimethylxanthine (2897 ng L⁻¹), 4-acetamidoantipyrine (191 ng L⁻¹), acetaminophen (165 ng L⁻¹) and rasagiline (152 ng L⁻¹) were found. This study examines POCIS deployment strategies, calibration, and analysis methods for 49 pharmaceutical compounds in an WWTP effluent. This research establishes a robust methodology for quantitative passive sampling of pharmaceuticals in aquatic environments, providing critical insights for more accurate monitoring of pharmaceuticals of environmental concern.