Identification and quantification of domoic acid by UHPLC/QTOF tandem mass spectrometry,with simultaneous identification of non-target photodegradation products

Amnesic shellfish poisoning is a potentially lethal human toxic syndrome which is caused by domoic acid (DA), a neurotoxin produced by marine phytoplankton, principally from Pseudonitzschia genus. In this report, a method to identify and quantify the DA toxin, with simultaneous identification of its photodegradation products, has been developed. It uses an ultra high performance liquid chromatography coupled to a quadrupole-time-of-flight tandem mass spectrometer (UHPLC–QTOF) after solid-phase extraction (SPE). An unambiguous identification of DA was carried out by considering both the retention time of DA in UHPLC and the exact mass of protonated DA molecule ([M + H]⁺ = 312.1447 m/z) and of the most intense fragment ion (m/z 266.1391). The quantification was conducted using protonated DA molecule with protonated Glafenin as internal standard, obtaining a limits of detection of 0.75 µg L^?1. Large screening with UHPLC–QTOF could also give structural information about degradation products of DA present in samples after UV-irradiation. This method was applied for the determination of DA in complex liquid samples after SPE and is applicable for environmental monitoring of this toxic substance in the aquatic environment.