Qualitative analysis of the most toxic and abundant microcystin variants (LR, RR, and YR) by using LCMS–IT–TOF

• The analysis of microcystin by using LCMS–IT–TOF technique.
• Analysis of MC variants including MC-LR, MC-RR, and MC-YR.
• LCMS–IT–TOF technique offered the lower detection limits of microcystin.
• Applied to the laboratory batch culture of Microcystis aeruginosa.

Contamination of microcystins (a family of heptapeptide hepatotoxins), in eutrophicated water bodies is a worldwide problem. Due to their acute and chronic poisoning of animal and human health even at a low concentration of ppb scale, the accurate analysis is required of all microcystin variants present in a sample. In this study, a sensitive and selective method for the analysis of microcystin-LR (MC-LR), microcystin-RR (MC-RR), and microcystin-YR (MC-YR) using the liquid chromatograph mass spectrometry–ion trap–time of flight (LCMS–IT–TOF) technique has been developed. A new approach to quantify and distinguish microcystin variants by using LCMS–IT–TOF, a novel hybrid mass spectrometer having the multistep tandem mass spectrometry (MSn) ability, excellent resolution, and mass accuracy, could provide highly accurate analysis for evaluation of the toxicity of microcystins in a sample. In addition, chromatographic and spectrometric conditions were optimized for high peak intensity and the fine peak separation of microcystin variants. The results obtained of multistep tandem MS spectra strongly verified the presence of the studied microcystin variants in samples, and offered the lower detection limits of 5 pg on a column for MC-RR, and 10 pg on a column for MC-LR and MC-YR under the given analytical conditions.