Abstract
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.
Highlights
In recent years, reports of cyanobacterial blooms have increased [1]
A two-way ANOVA analysis of the latter data suggested that the recoveries determined were not significantly different from a control recovery of 100 ± 10% obtained with MC congeners in MeOH solution (Over-Spike) applied to the UPLC-MS/MS without sample matrix and prior solid-phase extraction (SPE)
For the determination of the loss of the SPE procedure, MC congeners in MeOH solution were spiked to the sample after protein precipitation and liquid-liquid partitioning, but before the SPE procedure (Middle-Spike)
Summary
Water bodies experiencing cyanobacterial bloom formation often contain toxins, like microcystins (MCs), which can pose a serious health threat to humans. This was demonstrated in Caruaru in 1996, when 76 patients. ELISA methods may differ in differ the antibodies used, andused, and their capability to detect the majority of congeners present in a given sample. MC-LF [30], co-occur in aco-occur given cyanobacterial bloom [28,29], including theincluding highly toxic [30], the present the present aimed atoquantitation establish a quantitation a wider range of congeners complex work aimed work to establish method for method a wider for range of congeners in complexinmatrices matricesthe allowing theofanalysis congener specific organ distribution.
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