The increasing complexity of contaminant mixtures in surface waters has made traditional assessments of risk to human health and the environment progressively more difficult, requiring new and advanced, novel analytical approaches. For example, methods are needed to identify contaminants for which routine chemical analyses are not performed, in addition to prioritizing both detected and undetected chemicals by both biological and toxicological relevance. Tracking biotransformation products of chemical contaminants in an untargeted fashion facilitates the identification of xenobiotics taken up by the resident environmental species (e.g., fish), and can inform risk based on known detoxification pathways. As a first step, we investigated xenobiotic glucuronidation, which is generally accepted as the most biologically relevant phase II metabolic pathway for pharmaceuticals, pesticides, and other environmental contaminants frequently encountered by organisms in the environment. Glucuronidation consists of the attachment of a glucuronic acid moiety to the xenobiotic (or to its phase I metabolite(s)) to aid excretion and thus, we developed a novel untargeted mass spectrometry-based method for identifying these glucuronides in tissues and biofluids in aquatic species. The application of this method to gallbladders from fish exposed to wastewater treatment plant effluent revealed the presence of over 70 biologically relevant xenobiotic-glucuronides, the majority of which were not targets of conventional contaminant monitoring. These results highlight the need for developing novel, biologically based untargeted screening methods for evaluating chemical contaminants in complex environmental mixtures to aid in both human and ecological risk assessment.

Untargeted MS<sup>n</sup>-based monitoring of glucuronides in fish: Screening complex mixtures for contaminants with biological relevance

ACS Fall 2021

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Untargeted MSn-based monitoring of glucuronides in fish: Screening complex mixtures for contaminants with biological relevance

Untargeted MSⁿ-based monitoring of glucuronides in fish: Screening complex mixtures for contaminants with biological relevance