Voegel P D, Zhou W, Baldwin R P
Department of Chemistry, University of Louisville, Louisville, Kentucky 40292.
Anal Chem. 1997 Mar 1;69(5):951-7. doi: 10.1021/ac960748t.
The practical application of electrochemical detection in capillary electrophoresis has been hampered by irreproducibility and inconvenience related to capillary/electrode alignment. In order to eliminate these problems, a simple, flexible method by which the capillary and the working electrode were integrated into a single operational unit was devised and evaluated. The electrodes were formed by sputtering a thin conductive layer of Au or Pt onto the exit tip of the capillary. Depending on the size of the capillary used (i.e., both inner and outer diameters), Au on-capillary electrodes (OCEs) gave detection limits at the micromolar level and slightly below for the test analytes dopamine and catechol. More important, operation of the OCEs required no alignment procedures beyond immersion in the CE buffer reservoir/detector cell. OCEs used in this manner exhibited relative standard deviations of 2-4% for repeated injections even if removed from solution between runs. Finally, the Au and Pt OCEs could themselves be modified further by conventional electrochemical procedures. Here, Cu OCEs, formed by electrodeposition onto Au, were used to detect carbohydrate compounds; and an enzyme OCE, formed by adsorption of glucose oxidase onto Pt, was used to detect glucose.
毛细管电泳中电化学检测的实际应用一直受到与毛细管/电极对准相关的不可重复性和不便性的阻碍。为了消除这些问题，设计并评估了一种简单、灵活的方法，即将毛细管和工作电极集成到一个单一的操作单元中。通过在毛细管的出口端溅射一层薄的金或铂导电层来形成电极。根据所使用毛细管的尺寸（即内径和外径），金毛细管上电极（OCE）对测试分析物多巴胺和儿茶酚的检测限在微摩尔水平及略低于该水平。更重要的是，OCE的操作除了浸入毛细管电泳缓冲液储液器/检测池中之外，不需要对准程序。以这种方式使用的OCE即使在运行之间从溶液中取出，重复进样时的相对标准偏差也为2 - 4%。最后，金和铂OCE本身可以通过传统的电化学程序进一步修饰。在此，通过电沉积在金上形成的铜OCE用于检测碳水化合物化合物；通过将葡萄糖氧化酶吸附到铂上形成的酶OCE用于检测葡萄糖。
