Quantitative Analysis of Microcystin Cyclopeptides Using Ultra-Fast Triple Quadrupole LC-MS/MS: EPA Method 544

Cyanobacteria found in eutrophic or hypereutrophic freshwater may accumulate in surface water supplies as "blooms" or as "scums." Some species of cyanobacteria produce toxins, one of which are hepatotoxins called microcystins. At least 50 congeners of microcystins are known, and several of these may be produced during a bloom depending upon a variety of conditions. The chemical structure of microcystins includes two variable amino acids and an unusual aromatic amino acid, ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid). Different microcystins have different lipophilicities and polarities, which could affect their toxicity. In this application note, microcystins-RR, YR, and LR were measured using a Nexera UHPLC with a LCMS-8050 triple quadrupole MS detector with ESI ionization in accordance with EPA Method 544.