Liquid chromatography-mass spectrometry method to detect Tetrodotoxin and Its analogues in the puffer fish Lagocephalus sceleratus (Gmelin, 1789) from European waters

The presence of tetrodotoxin (TTX) and its analogues, 4-epiTTX, 4,9-anhydroTTX, 5-deoxyTTX, 11-deoxyTTX, 5,6,11-trideoxyTTX, 11-norTTX-6(S)-ol, and 11-norTTX-6(R)-ol was investigated for the first time in five different tissues (liver, gonads, gastrointestinal tract, muscle, and skin) of six specimens of the marine puffer fish Lagocephalus sceleratus from European waters (Aegean Sea, Greece) by using liquid chromatography coupled to electrospray ionisation mass spectrometry operating in the conventional mode in addition to low-energy collision dissociation tandem mass spectrometry (CID-MS/MS).Two isomers of 5,6,11-trideoxyTTX were detected in all specimens as the major TTX analogues, followed by 11-deoxyTTX, 11-norTTX-6(S)-ol, and TTX. However, minor amounts of 4-epiTTX, 4,9-anhydroTTX, 5-deoxyTTX, and 11-norTTX-6(R)-ol were also found in most of the tested tissues. In all puffer fish specimens, gonads, gastrointestinal tract, and liver contained the highest toxin levels, whereas muscle and skin contained lower amounts. Toxin distribution within the tissues of the six L. sceleratus specimens was different depending on fish size, area, and season where fish were caught. The LC-ESI-CID-MS/MS analysis employed is proposed as a suitable technique for determination of TTX and its analogues with a low detection limit (0.08 μg/g).