Determination of naproxen, ibuprofen and triclosan in wastewater using the polar organic chemical integrative sampler (POCIS): A laboratory calibration and field application

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In this study, the occurrence in wastewater of two non-steroidal anti-inflammatory drugs (NSAIDs), naproxen and ibuprofen, and one personal care product, triclosan, was assessed using the polar organic chemical integrative sampler (POCIS). The samplers were initially calibrated in the laboratory to obtain sampling rates (Rs ) for each target compound followed by deployment in the influent and effluent of Goudkoppies and Northern Wastewater Treatment Plants (WWTPs), South Africa. Exposure was done for 14 days in 2012. High performance liquid chromatography (HPLC) system with ultraviolet (UV) and fluorescence (FLD) detectors was used to analyse POCIS extracts. Laboratory calibration of POCIS yielded R values for the three compounds that were between 0.087 and 0.383 ℓ-d-1 in quiescent conditions, and 0.125 and 0.936 ℓ-d-1 in stirred conditions. From the accumulated amounts in field-deployed samplers, estimated freely dissolved concentrations of the studied compounds in wastewater influent ranged from 55.0 to 78.4 µg-ℓ-1 and 52.3 to 127.7 µg-ℓ-1 in Goudkoppies and Northern WWTPs, respectively. Average concentrations of these compounds in the treated effluent ranged from 10.7 to 13.5 µg-ℓ-1 in Goudkoppies WWTP, and 20.4 to 24.6 µg-ℓ-1 in Northern WWTP. Analyte removal efficiencies varied between 68 and 86% in Goudkoppies WWTP and 61 and 82% in Northern WWTP. Grab samples processed by SPE method yielded higher analyte concentrations (up to three-fold) as compared to POCIS-derived estimates. This discrepancy was attributed to SPE's ability to extract both the free dissolved, and particle sorbed fractions of the contaminants.