Cyanobacteria (blue-green algae) are photosynthetic organisms found in both marine and freshwater environments. The occurrence of algal blooms has increased over time, and anthropogenic input of phosphorus and nitrogen into natural water bodies are contributors to this increase in toxic algal blooms worldwide. Many species of cyanobacteria produce secondary metabolites, some of which are toxic to higher organisms. Microcystins are a group of non-ribosomally synthesized cyclic heptapeptides, of which microcystin-LR (MC-LR) is the most common.

Microcystins can be introduced to tissues of organisms through the diet or by ingestion of contaminated water. Microcystins are readily water-soluble so once ingested they accumulate in the liver via the bile acid transport system. The risk to human health due to the increasing presence of these toxins is concerning.

The World Health Organization (WHO) provisional guideline value for MC-LR of 1 μg/L, which was deemed protective of total microcystins, has been adopted as a basis for national standards or guideline values for drinking water in many countries.

Detection of microcystins is a challenging problem for water testing laboratories. Many laboratories have turned to liquid chromatography- tandem mass spectrometry (LC-MS/MS) for the concurrent analysis of a range of cyanotoxins. This application note describes a method for the analysis of drinking and surface waters for 10 well-known cyanotoxins;cylindrospermopsin (CYL), anatoxin-a (ANA) and microcystins nodularin (NOD), microcystin-LR (MC-LR), MC-DeRR, MC-RR, MC-YR, MC-LY, MC-LW, and MC-LF. The method uses direct injection of 50 μL of water sample with the ACQUITY UPLC I-Class System coupled to Xevo TQ-S.

This application note describes a UPLC-MS/MS method for the analysis of 10 cyanotoxins, including important microcystins, using standard addition, without the need for extraction at concentrations well below the WHO provisional guideline of 1 μg/L.