Anatoxin-a in Irish freshwater and cyanobacteria, determined using a new fluorimetric liquid chromatographic method.

A new sensitive high-performance liquid chromatographic (HPLC) method was used to determine anatoxin-a in freshwater, following blooms of cyanobacteria (blue-green algae). Anatoxin-a was converted into a highly fluorescent derivative using 4-fluoro-7-nitro-2,1,3-benzoxadiazole and HPLC analysis gave good linear calibrations even at low concentration ranges (1-10 micrograms/liter, r = 0.997). The detection limit for anatoxin-a was 0.02 ng/ml, and this new HPLC method should prove useful for the routine analysis of potable waters. Anatoxin-a was discovered in three major lakes in Ireland using this method and identification was confirmed using gas chromatraphy-mass spectrometry (GC-MS), following acetylation. Anatoxin-a was found in Anabaena, a planktonic cyanobacterium, as well as in a benthic Oscillatoria species. This is the first identification of anatoxin-a in Irish freshwater and this toxin was also implicated as the causative agent in incidents of fatal canine neurotoxicosis.