Determination of Microcystins and Nodularin in Drinking Water by UHPLC-MS/MS using a Luna Omega 1.6 µm Polar C18 (EPA Method 544)

Microcystin congeners like Microcystin-LR and Microcystin-RR are a class of toxins produced by cyanobacteria. They are cyclic heptapeptides that can cause serious damage to the liver (hepatoxic) once ingested. As environmental conditions change and encourage harmful algal blooms, drinking and irrigation water testing becomes highly important to ensure safety. In this application note we highlight a UHPLC-MS/MS method that analyzes six microcystin toxins and the cyclic pentapeptide nodularin. With the wide range of compound polarities present within this class of cyclic peptide toxins, a stationary phase with a balanced combination of polar and non-polar selectivity is needed to ensure adequate separation. The Luna Omega 1.6 µm Polar C18 was selected because of its enhanced polar retention alongside the hydrophobic non-polar selectivity of its C18 group. Additionally, the high efficiency and greater particle inertness of this column allows for greater resolution and higher sensitivity. Acknowledgement: We would especially like to thank David Schiessel and Babcock Laboratories for their support and use of their method, system, and standards for this application.