Amnesic shellfish poisoning toxins in bivalve molluscs in Ireland

In December 1999, domoic acid (DA) a potent neurotoxin, responsible for the syndrome Amnesic Shellfish Poisoning (ASP) was detected for the first time in shellfish harvested in Ireland. Two liquid chromatography (LC) methods were applied to quantify DA in shellfish after sample clean-up using solid-phase extraction (SPE) with strong anion exchange (SAX) cartridges. Toxin detection was achieved using photodiode array ultraviolet (LC-UV) and multiple tandem mass spectrometry (LC-MS(n)). DA was identified in four species of bivalve shellfish collected along the west and south coastal regions of the Republic of Ireland. The amount of DA that was present in three species was within EU guideline limits for sale of shellfish (20 microg DA/g); mussels (Mytilus edulis), <1.0 microg DA/g; oysters (Crassostrea edulis), <5.0 microg DA/g and razor clams (Ensis siliqua), <0.3 microg DA/g. However, king scallops (Pecten maximus) posed a significant human health hazard with levels up to 240 microg DA/g total tissues. Most scallop samples (55%) contained DA at levels greater than the regulatory limit. The DA levels in the digestive glands of some samples of scallops were among the highest that have ever been recorded (2,820 microg DA/g).