Solid-phase extraction clean-up of ciguatoxin-contaminated coral fish extracts for use in the mouse bioassay

Florisil solid-phase extraction (SPE) cartridges were used for purifying ciguatoxin (CTX)-contaminated coral fish extracts, with the aim of removing extracted lipid but retaining optimal level of CTXs in the purified fractions. The CTX-containing fraction (target fraction) in fish ether extract was isolated and purified by eluting through a commercially available Florisil cartridge with hexane–acetone–methanol solvent mixtures of increasing polarity (hexane–acetone (4:1, v/v) < acetone–methanol (7:3, v/v) < 100% methanol). Application of Florisil SPE using acetone–methanol (7:3, v/v) condition facilitated the separation of 4.2 ± 0.4 mg (mean ± standard error of the mean (SEM)) of purified target fraction from 20 mg ether extract with good retention of CTXs. The mouse bioassay was used to demonstrate that the average CTX recovery of the target fraction from CTX-spiked samples was 75.8% ± 3.3%, which was significantly increased by 96.7% ± 15% when compared with CTX recovery from ether extracts (44.8% ± 5.2%...