Multiresidue analysis of 24 Water Framework Directive priority substances by on-line solid phase extraction-liquid chromatography tandem mass spectrometry in environmental waters

•An on-line method for 24 priority substances from EU Directive was developed.•A high loaded octadecyl phase is proposed for the on-line solid phase extraction.•Good performance (accuracy, precision and limits of detection) was obtained.•The method is proposed to analyze drinking, surface and effluent wastewaters.•16 priority substances were detected in surface waters and effluent wastewaters.

This paper reports the development of a fully multiresidue and automated on-line solid phase extraction (SPE) - liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the determination of 24 priority substances (PS) belonging to different classes (pesticides, hormones or pharmaceuticals) included in the Directive 2013/39/UE and the recent Watch List (Decision 2015/495) in water samples (drinking water, surface water, and effluent wastewaters). LC-MS/MS conditions and on-line SPE parameters such as sorbent type, sample and wash volumes were optimized. The developed method is highly sensitive (limits of detection between 0.1 and 1.4 ng L−1) and precise (relative standard deviations lower than 8%). As part of the method validation studies, linearity, accuracy and matrix effects were assessed. The main advantage of this method over traditional off-line procedures is the minimization of tedious sample preparation increasing productivity and sample throughput.The optimized method was applied to the analysis of water samples and the results revealed the presence of 16 PS in river water and effluent water of wastewater treatment plants.