Quantitation and localization of beta-blockers and SSRIs accumulation in fathead minnows by complementary mass spectrometry analyses

Beta-blockers and selective serotonin reuptake inhibitors (SSRIs) enter the environment through the improper disposal of drugs in garbage, sinks, or toilets as well as via excretion after their intended use. Beta-blockers and SSRIs are resistant to biodegradation and highly water soluble, leading to limited removal capabilities by wastewater treatment plants. As a result, these compounds can easily enter the aquatic environment in a biologically active state, posing risks to the behavior, anatomy, and physiology of aquatic organisms through exposure. However, there is insufficient research on the effects of beta-blockers on aquatic vertebrates to have a complete understanding of the impact of beta-blocker pollution on aquatic organisms. Exposing fathead minnows at environmentally-relevant concentrations allows for an accurate representation of how beta-blockers and SSRIs affect and accumulate in aquatic vertebrates. Singular exposures to two beta-blockers and two selective serotonin reuptake inhibitors (SSRIs) at seven days modeled how pollution affects aquatic wildlife during acute exposure events. After exposure, the entire organism was analyzed quantitatively by liquid chromatography mass spectrometry and qualitatively by matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Imaging allowed for the determination of the part of the organism in which the drugs were accumulating. Results showed that after seven days of exposure there was accumulation of both the beta-blockers and SSRIs in the fathead minnows. This data represents the first application of LC-MS quantitation guided by MALDI-MSI in aquatic toxicology-type research in environmental analytical chemistry. [Display omitted] •Novel application of LC-MS and MSI to aquatic vertebrate toxicology•MSI guided LC-MS led to detection of analytes below LOD in whole organism.•Beta-blockers and SSRIs quantified in whole organism and organs support MSI data.•Toxicology results for analytes in high local concentration can be aided using MSI.