Caribbean ciguatoxin profile in raw and cooked fish implicated in ciguatera

► Cooked meal remnant and uncooked portion of CFP implicated fish examined. ► Demonstrated a tiered method for composite toxicity and confirmation of ciguatoxin. ► Similar cytotoxicity and ciguatoxin profiles observed in both samples. ► Several ciguatoxin analogues identified contributing to composite toxicity. A cooked meal remnant and uncooked portion of a Caribbean barracuda suspected in ciguatera fish poisoning were examined for the presence of ciguatoxins (CTX). Samples were analysed using a tiered method of CTX analysis consisting of in vitro cell (N2a) assay to assess composite toxicity and liquid chromatography-tandem mass spectrometry (LC–MS/MS) for structural confirmation. Meal remnant and uncooked fish extracts were cytotoxic by N2a cell assay and Caribbean ciguatoxin congener C-CTX-1 was structurally confirmed. Sample extracts were fractionated by LC and fractions analysed by the cell assay. The cytotoxicity profiles of cooked meal remnant and uncooked fish were similar. Cytotoxicity-guided LC–MS/MS analyses identified several CTX congeners contributing to the composite toxicity of the samples. C-CTX-1 was a major contributor, supporting its utility as a biomarker of Caribbean ciguatoxic fish.