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.