Hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) for determination of domoic acid in Adriatic shellfish

A new method for sensitive, specific and direct determination of domoic acid (DA), the causative toxin of amnesic shellfish poisoning (ASP) syndrome, in shellfish is proposed herein. It is based on combination of hydrophilic interaction liquid chromatography with mass spectrometry (HILIC-MS). The high percentage of organic modifier in the mobile phase and the omission of ion pairing reagents, both favoured in HILIC, result in enhanced detection limits with MS detection. The new method was set up either on a ionspray (ISI)-ion trap MS instrument operating in MS and MS/MS scanning acquisition modes, or on a turboionspray (TSI)-triple quadrupole MS system operating in selected ion monitoring (SIM) and multiple reaction monitoring (MRM) acquisition modes. Positive and negative ion experiments were performed. Multiple reaction monitoring experiments are recommended for screening contaminated shellfish tissue and for quantitative analyses due to highest sensitivity and selectivity. The minimum detection levels for the toxin in tissue were found to be 63 and 190 ng/g in positive and negative MRM experiments, respectively, which are well below the regulatory limit of DA in tissue (20 ug/g). Application to shellfish samples collected in the Adriatic Sea (Italy) in the period 2000-2004, demonstrated for the first time in Italy the presence of domoic acid as a new toxin that has entered the Adriatic Mytilus galloprovincialis toxin profile.