Bag-SPE--a convenient extraction method for screening of pharmaceutical residues in influent and effluent water from sewage treatment plants.

Bag-SPE is a solid-phase extraction (SPE) technique here applied to sample pharmaceutical residues in wastewater. The device, consisting of 20 mg polystyrene-divinylbenzene (PS-DVB) enclosed in a woven polyester fabric was immersed into a 20-mL sample. Extraction of the analytes was performed under gentle rotation (25 rpm) until distribution equilibrium was achieved (4 h). The extraction efficiency for thirteen pharmaceuticals was evaluated for the bag-SPE sampler compared to a conventional SPE cartridge (Oasis HLB). All analyses were determined on an ultra-performance liquid chromatography (UPLC) coupled to a quadrupole time-of-flight (QToF) mass spectrometer. The detection limit of the bag-SPE technique for the analytes in wastewater ranged from 15-100 ng/L with recoveries between 20.7% and 58.2% and ion suppressions between 2.2% and 53.2%. Although the extraction efficiencies were lower with the bag-SPE sampler compared to the SPE technique, the two methods showed similar detection limits due to the lower ion suppression experienced with the bag-SPE. The results demonstrate that bag-SPE is an attractive alternative to the more, in terms of manual handling, demanding SPE technique.