Determination of domoic acid by on-line coupled capillary isotachophoresis with capillary zone electrophoresis

An on-line coupled capillary isotachophoresis—capillary zone electrophoresis (cITP-CZE) method for the determination of domoic acid in shellfish and algae is described. The optimised cITP-CZE electrolyte system was 10 mM HCl + 20 mM β-alanine (BALA) + 0.05% hydroxyethylcellulose (leading electrolyte), 5 mM caproic acid (terminating electrolyte) and 20 mM caproic acid + 20 mM BALA + 0.1% HPMC (background electrolyte). A clear separation of the domoic acid from the other components of methanolic sample extract was achieved within 25 min. Method characteristics, i.e., linearity (0–200 μg/l), accuracy (recovery 101 ± 3%), intra-assay repeatability (2.4%) and detection limit (1.5 μg/l) were determined. Speed of analysis, low laboriousness, high sensitivity and low running cost are the typical attributes of the cITP-CZE method. Developed method was successfully applied to analysis of shellfish samples and food supplements containing algae extract.