title: LC- and GC-QTOF-MS as Complementary Tools for a Comprehensive Micropollutant Analysis in Aquatic Systems.
abstract: Efficient strategies are required to implement comprehensive suspect screening methods using high-resolution mass spectrometry within environmental monitoring campaigns. In this study, both liquid and gas chromatography time-of-flight mass spectrometry (LC-QTOF-MS and GC-QTOF-MS) were used to screen for >5000 target and suspect compounds in the Sacramento-San Joaquin River Delta in Northern California. LC-QTOF-MS data were acquired in All-Ions fragmentation mode in both positive and negative electrospray ionization (ESI). LC suspects were identified using two accurate mass LC-QTOF-MS/MS libraries containing pesticides, pharmaceuticals, and other environmental contaminants and a custom exact mass database with predicted transformation products (TPs). The additional fragment information from the All-Ions acquisition improved the confirmation of the compound identity, with a low false positive rate (9%). Overall, 25 targets, 73 suspects, and 5 TPs were detected. GC-QTOF-MS extracts were run in negative chemical ionization (NCI) for 21 targets (mainly pyrethroids) at sub-ng/L levels. For suspect screening, extracts were rerun in electron ionization (EI) mode with a retention time locked method using a GC-QTOF-MS pesticide library (containing exact mass fragments and retention times). Sixteen targets and 42 suspects were detected, of which 12 and 17, respectively, were not identified by LC-ESI-QTOF-MS. The results highlight the importance of analyzing water samples using multiple separation techniques and in multiple ionization modes to obtain a comprehensive chemical contaminant profile. The investigated river delta experiences significant pesticide inputs, leading to environmentally critical concentrations during rain events.
authors.affiliation: Department of Civil and Environmental Engineering, University of California , One Shields Avenue, Davis, California 95616, United States.
authors.forename: Christoph
authors.initials: C
authors.lastname: Moschet
authors.affiliation: Department of Civil and Environmental Engineering, University of California , One Shields Avenue, Davis, California 95616, United States.
authors.forename: Bonny M
authors.initials: BM
authors.lastname: Lew
authors.affiliation: Department of Civil and Environmental Engineering, University of California , One Shields Avenue, Davis, California 95616, United States.
authors.forename: Simone
authors.initials: S
authors.lastname: Hasenbein
authors.affiliation: Agilent Technologies Inc., 2850 Centerville Road, Wilmington, Delaware 19808, United States.
authors.forename: Tarun
authors.initials: T
authors.lastname: Anumol
authors.affiliation: Department of Civil and Environmental Engineering, University of California , One Shields Avenue, Davis, California 95616, United States.
authors.forename: Thomas M
authors.identifier: 0000-0001-7217-4753
authors.initials: TM
authors.lastname: Young
mesh_terms: D002853:Chromatography, Liquid; D008401:Gas Chromatography-Mass Spectrometry; D010575:Pesticides; D045483:Rivers; D053719:Tandem Mass Spectrometry
chemical_list: D010575:Pesticides