低电渗流毛细管区带电泳分离芳香胺

利用低pH值（pH≤2.0）有效地抑制电渗流,建立起低电渗流毛细管区带电泳(CZE)体系，并分离了7种芳香胺。在此体系中,芳香胺质子化而带正电荷,故采用在毛细管阳极端进样,阴极端检测。实验考察了pH值、电解质浓度对分离的影响,结果发现,当pH＜p K a （p K a =14-p K b ）时,pH值的微小增大会导致芳香胺的迁移时间迅速延长；芳香胺的出峰次序与其p K b 值及分子中含有的胺基和酸性取代基的数目有关,分子中含胺基愈多,p K b 值愈小,出峰愈早；芳香胺含酸性取代基则使峰序滞后。

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).