Simultaneous Detection of 14 Microcystin Congeners from Tissue Samples Using UPLC- ESI-MS/MS and Two Different Deuterated Synthetic Microcystins as Internal Standards

Stefan Altaner , Jonathan Puddick , Valérie Fessard (1) , Daniel Feurstein , Ivan Zemskov , Valentin Wittmann , Daniel R Dietrich

1 Laboratoire de Fougères - ANSES

Cyanobacterial microcystins (MCs), potent serine/threonine-phosphatase inhibitors, pose an increasing threat to humans. Current detection methods are optimised for water matrices with only a few MC congeners simultaneously detected. However, as MC congeners are known to differ in their toxicity, methods are needed that simultaneously quantify the congeners present, thus allowing for summary hazard and risk assessment. Moreover, detection of MCs should be expanded to complex matrices, e.g., blood and tissue samples, to verify in situ MC concentrations, thus providing for improved exposure assessment and hazard interpretation. To achieve this, we applied two synthetic deuterated MC standards and optimised the tissue extraction protocol for the simultaneous detection of 14 MC congeners in a single ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) run. This procedure was validated using plasma and liver homogenates of mice (male and female) spiked with deuterated MC standards. For proof of concept, tissue and plasma samples from mice i.p. injected with MC-LR and MC-LF were analysed. While MC-LF was detected in all tissue samples of both sexes, detection of MC-LR was restricted to liver samples of male mice, suggesting different toxicokinetics in males, e.g., transport, conjugation or protein binding. Thus, deconjugation/-proteinisation steps should be employed to improve detection of bound MC. Key Contribution: The use of deuterated microcystin standards and an improved extraction procedure using UPLC-MS/MS analytics, provides for the simultaneous detection of fourteen microcystin congeners. Thus, it allows more accurate quantitation of total microcystin load of a given sample in complex matrices like blood or tissue, and therefore better hazard interpretation.

Keywords: cyanobacterial toxin; deuterated MC standards; microcystin; blood; liver tissue; UPLC-MS/MS; quantification; detection; toxicology; toxicity; human; contaminant; cyanobacteria; congener

Keywords: cyanobactérie; microcystine; sang; foie; tissue; UPLC-MS/MS; détection; toxicologie; toxicité; humain; contaminant; congénère

Domains: Toxicology

Stefan Altaner, Jonathan Puddick, Valérie Fessard, Daniel Feurstein, Ivan Zemskov, et al.. Simultaneous Detection of 14 Microcystin Congeners from Tissue Samples Using UPLC- ESI-MS/MS and Two Different Deuterated Synthetic Microcystins as Internal Standards. Toxins, 2019, 11 (7), pp.388. ⟨10.3390/toxins11070388⟩. ⟨anses-02347418⟩