PARENT SESSION

3. Algal Toxins
Hall 6
8:30 AM - 5:30 PM, Wednesday, 30 April 2003
Chair: Pflugmacher, S.¹, ¹
Co-chair: Wiegand, C.², ²

(WE4/6) Detection and quantification of microcystins.

McElhiney , J.¹, Lawton, L.¹, ¹ Robert Gordon University, School of Life Sciences, Aberdeen, United Kingdom

ABSTRACT- Concern regarding the presence of microcystins (cyanobacterial hepatotoxins) in drinking water and their possible contamination in food (e.g. salad vegetables, fish and shellfish) has resulted in the need for reliable methods for the detection and accurate quantification of this class of toxins. A number of different analytical methods have been developed with high-performance liquid chromatography using photodiode array detection (HPLC-PDA) being one of the most readily adopted. Other much more sensitive assay based methods have also proved extremely useful, specifically antibody detection such as ELISA and the enzymes assay for protein phosphatase inhibition. One of the key difficulties hampering the accurate identification and quantification of microcystins is the availability of a wide range of purified microcystins. Although over sixty variants have now been reported only a very small number are commercially available and no calibrated standards have yet become obtainable. This has led to the common practice of reporting microcystin-LR equivalence regardless of which variant is present. The increased availability and use of HPLC with online mass spectral analysis (HPLC-MS) may in part help in the identification of microcystin variants but it must be remembered that a number of microcystins share the same molecular mass making definitive identification difficult. Another area of difficulty in microcystin analysis is sample concentration and clean-up. To facilitate HPLC analysis of microcystins at environmental concentrations it is necessary to enrich the sample typically by solid phase extraction (SPE). This method can also be utilised to remove matrix interference from more complex samples such as plant material. However, since both the immunological and enzyme-based assays can detect microcystins at several orders of magnitude lower, concentration and clean-up are not always necessary.

Key words: cyanobacterial hepatotoxins, microcystins