Analysis of cyanobacterial hepatotoxins in water samples by microbore reversed-phase liquid chromatography–electrospray ionisation mass spectrometry

A method based on liquid chromatography coupled to mass spectrometry with positive electrospray ionisation was developed for the analysis of cyanobacterial hepatotoxins in environmental samples. The chromatographic separation was performed using two microbore columns, 2 mm and 1 mm I.D. columns, which allowed the coupling of liquid chromatography to mass spectrometry with no flow splitting. Analytes were eluted using two different water–acetonitrile, both acidified with formic acid gradients. Mass spectrometric parameters were optimised in order to maximise sensitivity. Detection limits for the 2 mm I.D. column ranged from 0.077 to 2.057 ng in full scan and from 0.021 to 1.153 ng in SIM mode. However, limits of detection as low as 60–340 pg in full scan and 6–72 pg in SIM mode were achieved for the 1 mm I.D. column. Finally, the proposed method was applied to the analysis of microcystins and nodularins in real samples.