Calibration and field validation of POCIS passive samplers for tracking artificial sweeteners as indicators of municipal wastewater contamination in surface waters.

Abstract

Polar organic chemical integrative samplers (POCIS) are widely used to track contaminants in surface waters. However, POCIS have not been used previously to monitor for artificial sweeteners as an indicator of wastewater pollution. In this study, we report for the first time the POCIS sampling rates (Rscal) for four artificial sweetener compounds, acesulfame (0.001 L/day), sucralose (0.114 L/day), cyclamate (0.001 L/day), and saccharin (0.002 L/day). We also prepared a modified POCIS with Strata X-AW anion exchange resin as a sorbent (i.e., ax-POCIS) and determined the sampling rates for sucralose (0.060 L/day) and acesulfame (0.128 L/day). Rscal values were adjusted according to the rate of loss of the performance reference compound, metoprolol-d6 from deployed POCIS to yield field sampling rates (i.e., Rsfield). Field validation of the monitoring method was conducted in Presqu'ile Bay on the north-central coast of Lake Ontario that is impacted by discharges from a sewage lagoon. POCIS were deployed at four sites within the bay and in the lagoon discharge. The four artificial sweeteners, as well as caffeine, ibuprofen, and other microcontaminants of sewage origin, were present throughout the bay at estimated concentrations in the ng/L range, and in the lagoon discharge at estimated concentrations higher by approximately one order of magnitude. Because acesulfame is present in ionic form over the pH range of natural waters, there are uncertainties related to the sampling rates using the standard POCIS. Sucralose is recommended as the best choice for source tracking using POCIS. There was good agreement between the concentrations of sucralose estimated from POCIS and the measured concentrations in grab samples of surface water in the bay. The present study provides key data for monitoring artificial sweeteners using POCIS.