Development of an LC-MS/MS method to simultaneously monitor maitotoxins and selected ciguatoxins in algal cultures and P-CTX-1B in fish.

Ciguatera fish poisoning is a serious human health issue that is highly localized to tropical and sub-tropical coastal areas, affecting many of the indigenous island communities intrinsically linked to reef systems for sustenance and trade. It is caused by the consumption of reef fish contaminated with ciguatoxins and is reported as the most common cause of non-bacterial food poisoning. The causative toxins bioaccumulate up the food web, from small herbivorous fish that graze on microalgae of the genus Gambierdiscus into the higher trophic level omnivorous and carnivorous fish predating on them. The number of Gambierdiscus species being described is increasing rapidly and the role of other toxins produced by this microalgal genus in ciguatera intoxications, such as maitotoxin, remains unclear. Ciguatoxins and maitotoxin are among the most potent marine toxins known and there are currently no methods of analysis that can simultaneously monitor these toxins with a high degree of specificity. To meet this need a rapid and selective ultra-performance liquid chromatography tandem mass spectrometry method has been developed to rapidly screen Gambierdiscus cultures and environmental sample device extracts for ciguatoxins and maitotoxins. A fast sample preparation method has also been developed to allow sensitive quantification of the potent ciguatoxin fish metabolite P-CTX-1B from fish extracts, and this method has been subjected to a small validation study. Novel aspects of this approach include the use of alkaline mobile phase for chromatographic separation and specific monitoring of the various toxins. This method has good potential to help evaluate ciguatera risk associated with Gambierdiscus and related microalgal species, and to help promote method development activities for this important and analytically challenging toxin class.