Simultaneous Analysis of Microcystins, Cylindrospermopsin, Anatoxin, and Nodularin in Lake Water by Liquid Chromatography-Tandem Mass Spectrometry

Objective To establish a method for simultaneous determination of trace levels of microcystins, cylindrospermopsin, anatoxin, and nodularin in lake water based on liquid chromatography-tandem mass spectrometry (LC-MS/MS).

Methods After being adjusted to alkaline conditions and mixed with six internal standards, the water samples were enriched using dual HLB and ENVI-Carb cartridges. The eluates were then evaporated under nitrogen, reconstituted, and subjected to instrumental analysis. Both water and acetonitrile containing 0.1% formic acid were used as mobile phases. An ACQUITY UPLC® BEH C₁₈ column (150 mm × 2.1 mm, 1.7 μm) was selected to separate the target cyanotoxins. Multiple reaction monitoring was applied for data acquisition, and quantification was accomplished using internal standard methods.

Results Within certain concentration ranges, all 14 cyanotoxins examined in the study showed good linearity, with all correlation coefficients greater than 0.998. When the water volume was 100 mL, the limits of detection and quantification for the 14 cyanotoxins were 0.1-0.9 ng/L and 0.3-2.9 ng/L, respectively, and spiked recoveries and relative standard deviations were 81.7%-132.9% and 1.2%-14.9%, respectively. In the 10 lake water samples analyzed, cylindrospermopsin, anatoxin-α, and multiple microcystins were detected.

Conclusion The method developed in the study has high-throughput capacity, as well as high sensitivity, accuracy, and reliability. The method can be applied in the simultaneous detection of microcystins, cylindrospermopsin, anatoxin, and nodularin in lake water.