Determination of microcystins and nodularins in ambient freshwater and seawater by liquid chromatography-mass spectrometry including toxin screening and identification.

Background: Microcystins (MCs) and nodularins (NODs) produced by cyanobacteria occur in ambient freshwaters and across the freshwater-marine continuum, and pose health threats through drinking and recreational waters, as well as food resources. Approximately 300 MC and NOD toxins have been published, but less than 15 of them are commercially available as toxin standards. Our aim herein was to rapidly identify and quantify all toxin congeners, including those without standards, in water samples even at low abundance by reversed-phase solid phase extraction (SPE)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) to provide insights into toxin levels and potential toxicity.