Abstract: Domoic acid （DA） is a kind of neurotoxin produced by Pseudo-nitzschia diatom that can accumulate in shellfish. Consuming shellfish products contaminated by domoic acid can cause memory loss, dizziness, coma and even death. In this paper, a method was established for the simultaneous determination of domoic acid （DA） in shellfish by liquid chromatography-orbitrap mass spectrometry. Oyster and clam samples were extracted with methanol and purified with QuEChERS technology. The analytes were isolated by Hypersil GOLD C₁₈ column and gradient eluted with acetonitrile-2 mmol/L ammonium formate solution （0.2% formic acid）. DA were determined by orbitrap mass spectrometry through positive ion scanning, full scan mode and data dependent scan mode. The experimental results indicated that the retention time of DA was all within 6min. The limits of quantification （LOQ） was 0.01 mg/kg. The calibration curves showed good linearity within the concentration range of 25~500 μg/L, R²=0.999 8. The average recoveries was between 90.5%~106.3% and the relative standard deviations （RSD） were less than 6.0% （n=6）. This method was easy, rapid and sensitive, and could be applied in the determination of domoic acid in shellfish.

Key words: amnesic shellfish toxin, domoic acid, high resolution mass spectrometry