Rapid extraction combined with LC-tandem mass spectrometry (CREM-LC/MS/MS) for the determination of ciguatoxins in ciguateric fish flesh

Ciguatera is a significant food borne disease caused by potent polyether toxins known as ciguatoxins, which accumulate in the flesh of ciguateric fish at risk levels above 0.1 ppb. The management of ciguatera has been hindered by the lack of analytical methods to detect and quantify clinically relevant levels of ciguatoxin in easily prepared crude extracts of fish. Here we report a ciguatoxin rapid extraction method (CREM) that allows the rapid preparation of fish flesh extracts for the detection and quantification of ciguatoxin by gradient reversed-phase liquid chromatography-tandem mass spectrometry (LC/MS/MS). CREM-LC/MS/MS delivers a linear response to P-CTX-1 spiked into fish prior to extraction. A similar response was obtained for P-CTX-1 spiked after extraction, indicating >95% extraction efficiency was achieved overall and 85% at the limit of quantification (0.1 ppb). Using this approach, levels ≥0.1 ppb P-CTX-1 could be detected and quantified from an extract of 2 g fish flesh, making it suitable as a confirmatory assay for suspect ciguateric carnivorous fish in the Pacific Ocean. The approach is designed to simplify the extraction and analysis of multiple samples per day.