A new configuration of polar organic chemical integrative sampler with nylon membranes to monitor emerging organophosphate ester contaminants in urban surface water

Abstract

Organophosphate ester contaminants, including organophosphate pesticides (OPPs) and organophosphate flame retardants (OPFRs) are ubiquitous in surface water and pose a significant risk to aquatic organisms, thus it is important to develop effective methods for long-term monitoring of these emerging compounds. Polar organic chemical integrative sampler (POCIS) has become a promising monitoring tool for waterborne contaminants, yet recent studies found that the commonly used polyethersulfone (PES) membrane strongly sorbed some moderately hydrophobic compounds, resulting in long lag-phase for chemical accumulation in POCIS. In the present study, 0.45-μm nylon membranes was selected as POCIS diffusion-limiting membrane to design a new POCIS-Nylon configuration for analyzing moderately hydrophobic OPPs and OPFRs in water. The POCIS-Nylon had negligible lag-phase due to low sorption of OPPs and OPFRs to nylon membrane. Meanwhile, linear accumulation time and sensitivity for target contaminants using POCIS-Nylon retained similar to the traditional POCIS. Water velocity and chemical concentration had little impact on sampling rate (Rs), validating that the POCIS-Nylon was suitable for various water conditions. Finally, the occurrence of OPPs and OPFRs in urban waterways of Guangzhou, China was evaluated using the POCIS-Nylon with Rs values that were calibrated in the laboratory. The average concentration of OPPs was 4.97 ± 1.35 ng/L (range: 2.64 ± 1.28–6.54 ± 0.18 ng/L) and the average concentration of OPFRs was 400 ± 88 ng/L (range: 316 ± 24–615 ± 36 ng/L) across nine sampling sites. The present study provides a way to resolve the inherent challenge of accumulating hydrophobic substances by POCIS.