Mass spectrometric detection of nodularin and desmethylnodularin in mussels and flounders

Samples of mussels and flounders from the Baltic Sea were analysed for nodularin content on two different LC–MS instruments (triple quadrupole and ion trap). The triple quadrupole instrument was well suited for the quantitative analysis. The limit of detection in the selected ion recording mode was 5 pg and in the multiple reactant monitoring mode 500 pg on column for extracts of Nodularia spumigena. The fragmentation patterns of nodularin-R and desmethylnodularin-R were recorded and shown to be similar to those of microcystins. LC–MS proved to be an excellent tool for the analyses of cyanobacterial hepatotoxins in complex matrices.