Domoic acid (DA), the amnesic shellfish poisoning toxin (ASP), is an excitatory amino acid that can accumulate, under certain environmental conditions, in shellfish, finfish, birds, and mammals, by direct filtration or by feeding on contaminated organisms (Mos 2001). This potent neurotoxin with three carboxylic groups, responsible for its high polarity and hydrophilicity, is a cyclic amino acid and a secondary amine with a molecular weight of 311 Daltons. DA belongs to a neurotransmitter class of compounds with a structure very similar to an important neurotransmitter excitatory, acid glutamate, and indeed mimics glutamate in its interaction with some of its receptor subtypes. DA can damage the neurons by activating R-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate receptors, causing an influx of calcium, and then be the cause of several symptoms such as nausea, disorientation, temporary amnesia and, in more serious cases, persistent memory loss and/or coma, and ultimately even death (Costa et al. 2010). This toxin was originally isolated from a red microalga Chondria armata by Japanese researchers (Takemoto and Daigo 1958) and is now reported to be produced in several species of marine diatoms from the genus Pseudo-nitzschia. DA was identified as the causative agent of the well-known tragic intoxication event observed in 1987 (Prince Edward Island from Cardigan Bay in Eastern Canada). More than one hundred people became ill and three victims died, by septic shock or pneumonia, 11-24 days after intoxication. Whereas most victims recovered within 10 days, after a period of confusion and nausea, the others continued to show signs of selective short-term memory loss (Bates et al. 1989). Additional consequences of the DA presence included the temporary closure of shellfish aquaculture industries and a strong impact on tourism activities (Pistocchi et al. 2012;Trainer et al. 2012).The detection limit of the method generally considered as the reference for particulate DA quantification in marine organisms (high-performance liquid chromatography with ultra-violet detection at λ = 242 nm, HPLC-UV) ranges between 13 and 250 nM depending on the detector (Quilliam 2003). This sensitivity threshold is often insufficient to follow the dynamics of both dissolved and particulate domoic acid
AbstractDomoic acid (DA), a toxin produced worldwide by some species of the genus Pseudo-nitzschia, is responsible for contamination of marine molluscs, mammals, birds, and for human intoxication, and when detected in high levels results in closures of shellfish farms, thus causing severe economic losses to aquaculture. Studies on algal production of DA in cultures and field samples require sensitive methods capable of measuring trace concentrations of domoic acid. Measuring domoic acid concentrations at trace levels is still a significant challenge. A sensitive and reliable double derivatization using o-phthaldialdehyde-mercaptoethanol/9-fluorenylmethylchloroformate (OPA-MeSH/FMOC-Cl) followed by high-performance liq...