LC–ESI-Q-TOF-MS for faster and accurate determination of microcystins and nodularins in serum

Abstract

Microcystins (MC) and nodularins (Nod) are cyclic peptide hepatotoxins and tumour promoters produced by cyanobacteria. This study deals with liquid chromatography–mass spectrometry (LC–MS) analyses of 9 major cyanobacterial peptide toxins, starting with a comparison of six small particle size reversed-phase HPLC columns, from which one, Phenomenex Synergi Hydro-RP, was chosen for further chromatography with accurate mass MS studies in a complex biological fluid, serum. The instrumentation used for the serum sample analysis included a Bruker micrO-TOF-Q-MS coupled to an Agilent 1200RR LC system. Total analysis run time per sample was 8.5 min. The Q-TOF-MS instrument was operated on auto MS–MS mode to obtain fragment ions (such as the characteristic fragment m/ z 135 from Adda amino acid residue) for toxin identification purposes. Detected mass errors in serum samples were in the range of from 0.3 mDa to 9.1 mDa. The narrow mass window (±20 mDa) for mass chromatograms used in quantitation gave benefits by background noise reduction. We conclude that a LC–ESI-Q-TOF-MS instrumentation is a powerful tool for identification and quantitation of cyanobacterial peptide toxins in a biological matrix.