Method for the determination of imazamox and its two hydroxy and glucose conjugate metabolites in adzuki beans by capillary electrophoresis

A new method was developed for the simultaneous assay of the parent compound imazamox and its two relatively polar hydroxy and glucose conjugate metabolites, in adzuki beans. The method uses a capillary electrophoresis instrument equipped with a high-sensitivity flow cell and a UV detector. The simultaneous analysis of imazamox and its metabolites has been difficult to achieve by the conventional methods (HPLC and GC) because of the non-volatility and intense polarity of he glucose conjugate compound under the conditions of such analyses. The alternative, highly selective separation capabilities of the capillary electrophoresis (CE) instrument made the new method feasible. By this method, determination of residues of imazamox in adzuki beans was performed. Residues were extracted from adzuki bean samples with acidic water-methanol. After precipitation, centrifugation and solid-phase extraction of the imazamox residues, the parent compound and its metabolites were quantitated by capillary electrophoresis. The limit of detection by the method was 0.01 ppm for each compound. Rates of recovery of imazamox and its metabolites from spiked control samples were more than 73% in each analysis. The residue levels of the parent compound and its hydroxy and glucose conjugate metabolites were below 0.01 ppm (the limit of detection by the method) in each treated sample.