[Separation of aromatic amines by capillary zone electrophoresis with lower electroosmotic flow].

It is effective to restrain the electroosmotic flow (EOF) with lower pH value (pH < or = 2.0). As a result, a capillary zone electrophoretic (CZE) system of lower electroosmotic flow was established. Seven aromatic amines were separated by CZE with lower electroosmotic flow. In the system, the aromatic amines combined with protons under the experimental conditions, and had positive charges. Therefore, the sample entered the capillary at the positive electrode and was detected at the negative electrode. It was found that the migration time of aromatic amines increased quickly with a slight increase in pH value in CZE at lower electroosmotic flow. The retention order of peaks of aromatic amines is related to their pKb and the numbers of amino and acidic groups. When the number of amino groups gets larger, the pKb becomes smaller, and the peaks elute earlier. The acidic groups of aromatic amines make the peaks to elute later. The optimal conditions were 40 mmol/L NaH2PO4 (pH 1.7).