Analysis of microcystins in freshwater samples using high performance liquid chromatography and an enzyme-linked immunosorbent assay.

Blooms of non-toxin producing and toxin producing cyanobacteria are often observed in lakes, reservoirs and slowly flowing eutrophic freshwater. Microcystin congeners are the most important group of cyanobacterial toxins and determination of the microcystin concentration is necessary in order to assess the health risk when such waters are used for recreational purposes. The most widely used standard method for analysis of microcystins is high-performance liquid chromatography (HPLC). But this technique is time-consuming and needs a special expensive equipement. Therefore a commercially available microcystin enzyme-linked immunosorbent assay (ELISA) could be an alternative. However, when performed as recommended by the manufacturer, the ELISA is not suitable for a valid quantitative analysis. We have therefore modified the microcystin extraction method and the ELISA protocol and have been able to use the ELISA for a quantitative analysis comparable to that of the widely recommended HPLC method. The modified ELISA provides a relatively simple and highly sensitive approach for the quantitative analysis of microcystins in freshwater. Results can be obtained within two to three days after sampling.