Continuous flow hollow fiber liquid-phase microextraction and monitoring of NSAIDpharmaceuticals in a sewage treatment plant effluent

Abstract

A method for simultaneous extraction and quantification of four non-steroidal anti-inflammatory drugs (NSAIDs) based on continuous flow hollow fiber liquid-phase microextraction (CFHF-LPME) was developed. The effect of sample flow rate, acceptor flow rate, type of acceptor flow (continuous, semi-continuous or forward–backward), type of supported liquid membrane and sample volume was studied. The extraction of the final method was linear over an environmentally relevant concentration range and yielded high enrichment factors (720–940 times) in reagent water and (270–800 times) in sewage water for all analytes within 45 min. Repeatability was best (RSD 6–15%) during the first 30 min of extraction. The optimised method was used to monitor the occurrence and fate of the four NSAIDs in a Swedish sewage treatment plant (STP) effluent, which is discharged into a system of ponds before release into a river, during the period May–September 2008. All four analytes were detected at concentrations up to 0.92 µg L⁻¹ketoprofen, 0.08 µg L⁻¹naproxen, 0.43 µg L⁻¹diclofenac and 0.25 µg L⁻¹ibuprofen. A concentration drop during the summer was observed. For diclofenac and ketoprofen significant removal in the primary recipient pond system was observed. The presence of the studied pharmaceuticals in STP effluent together with concern about their environmental effects makes monitoring of their occurrence and knowledge of their environmental fate important. The proposed method provides a basis for automation of extraction towards on-site extraction using CFHF-LPME.