Untargeted analysis of contaminants in river water samples: Comparison between two different sorbents for solid-phase extraction followed by liquid chromatography-high-resolution mass spectrometry determination.

[Display omitted] • Optimization of Oasis HLB and GCB SPE sorbents for water contaminant extraction. • Comparable extraction recoveries observed for the 2 SPE sorbents (both used) • Untargeted analysis of river water samples by SPE and LC-high resolution (HR)MS. • Tentative identification of 241 compounds (mainly drugs) by match in HRMS database. • Different contamination levels depending on sample collection point of Rome municipality. In this work, an untargeted approach based on ultra-high performance liquid chromatography coupled to high-resolution tandem mass spectrometry (UHPLC-HRMS/MS) was employed for the analysis of contaminants in surface water samples, possibly deriving from an ineffective removal by wastewater treatment plants or illicit release. First, solid-phase extraction (SPE) conditions for 30 target compounds were optimized for two different sorbents, namely the commercial Oasis HLB and graphitized carbon black (GCB), by Box-Behnken designs of experiments. Upon identification of optimal conditions, the two SPE materials yielded comparable extraction recoveries, ranging between 52 and 110% and 55–100% for Oasis HLB and GCB, respectively. Thereafter, river water samples collected in five locations near Rome (Italy) were extracted using both sorbents and then analyzed by UHPLC-HRMS/MS in both positive and negative electrospray (ESI) ion polarities. The retrieved raw data files were submitted to Compound Discoverer software and compound identification was tentatively assigned by matching their tandem mass spectra with the mzCloud mass spectral library and manual validation, resulting in a total of 241 identified compounds (211 and 40 in positive and negative ESI mode, respectively), mainly belonging to pharmaceuticals. [ABSTRACT FROM AUTHOR]