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.

Recent advances in the design and application of electrochemical detection (EC) systems in capillary electrophoresis (CE) are reviewed, with the objective of providing the non-electrochemist with a state-of-the-art picture of CEEC instrumentation and an overview of the primary analytes and samples for which the technique is best suited. In particular, instrument innovations designed to aid in decoupling the CE and EC systems electrically and in aligning them physically are described in detail. In addition, CEEC applications are summarized for four specific analyte groups: catecholamines, thiols and disulfides, amino acids, and carbohydrates. On this basis, it is clear that EC techniques have reached a stage where they are already having a significant impact on CE usage in selected areas of analysis. Continued developments with respect to new electrode materials and electrode configurations promise to broaden this impact further.

Aminoglycoside antibiotics including gentamicin, bekanamycin, tobramycin, lincomycin, neomycin, kanamycin, and ribostamycin have been determined by CE-EC with copper electrodes. Both copper wall-jet electrodes (WJEs) and copper on-capillary electrodes (OCEs) were evaluated. The OCEs provided pM detection limits, superior stability and reproducibility (2-3 % relalive standard deviation in oxidation current), and a simple instrumental set-up without the need for capillary/electrode alignment. The analytical capabilities of the Cu-OCE were examined, following the optimization of CE conditions, for the seven aminoglycosides above; and the practical utility of this approach was demonstrated through the determination of aminoglycoside antibiotics in three pharmaceutical preparations.

A new approach for dual electrode electrochemical detection in capillary electrophoresis (CEEC) is described. In this approach, two identical capillaries, each containing an on-capillary electrode incorporated permanently onto its tip, were paired together for simultaneous sample injection and detection. This procedure permitted dual-parallel detection to be performed without the need for painstaking alignment of the electrodes with respect to one another and to the capillary outlet as is required for the off-capillary microelectrode systems usually employed in CEEC. As a result, independent detection at two electrodes held at different potentials or at two electrodes of different composition or structure could be performed simply and with wide flexibility. Fabrication of on-capillary electrodes was carried out by sputter-coating the exit end of the capillaries with a thin layer of Au or Pt. Dual electrode system performance was demonstrated by separation and analysis of phenol and catechol samples. In addition, the detection system was coupled with glucose oxidase for the selective detection of glucose.

The effectiveness of the student-to-student chemistry initiative in changing the attitudes of elementary school students towards science is analyzed. High school students trained by the Midwestern State University department of chemistry performed a series of chemistry demonstrations at elementary schools. The elementary school students completed identical surveys before and after the demonstrations. These surveys documented the impact of the program on elementary school students’ general attitudes toward science, interest in scientific careers, and increased awareness of chemical processes they often encounter in their lives. The survey results reveal statistically significant improvements in all three areas of analysis (p < 0.02 in all cases).