Sensitive profiling of trace neurotoxin domoic acid by pressurized capillary electrochromatography with laser-induced fluorescence detection

A stable, sensitive and low-reagent consumption method for the quantification of trace neurotoxin domoic acid (DA) was presented by pressurized capillary electrochromatography (pCEC) with laser-induced fluorescence (LIF) detection. Migration behaviours of DA were studied under different separation modes such as pCEC and capillary HPLC. Separation parameters including the mobile phase, applied voltage, supplementary pressure and sample loading rate were investigated. Double modes including electrophoretic migration and chromatographic retention were employed and an efficient separation of DA was achieved with a flow of 1.2 μL min⁻¹ in a capillary column. Sensitive analysis of DA was achieved with a detection limit of DA in shellfish tissue extracts as low as 10 ng mL⁻¹ (equivalent to 15 ng DA per g, wet weight). The stability and repeatability of pCEC-LIF was evaluated and a good result was gained with RSDs (n = 3) for the retention time and peak area of DA less than 0.5% and 2.0%, respectively. Applied to shellfish samples, the recoveries were satisfactory and the variation of the quantification of DA was acceptable when compared with the HPLC-MS/MS method.