Microelectrode Applications of Pulsed Electrochemical Detection

Abstract

Pulsed electrochemical detection (PED) has been applied to the direct (i.e., requires no derivatization), sensitive and reproducible detection of numerous polar aliphatic compounds (e.g., carbohydrates, amines, and thiols). These compounds, many of which have biological significance, typically have been classified as non-electroactive for detection under constant applied potentials and have poor optical detection properties. PED exploits the electrocatalytic activity of noble metal (e.g., Au and Pt) electrode surfaces to oxidize various polar functional groups using multi-step potential-time waveforms to realize amperometric/coulometric detection while maintaining uniform and reproducible electrode activity. The response mechanisms in PED are dominated by the surface properties of the electrode, and as a consequence, members of each chemical class of compounds produce virtually identical voltammetric responses. Thus, the full analytical potential is achieved when combined with an a priori separation. Although popularized in combination with high performance liquid chromatography, the combination of PED with highly efficient microseparation techniques offer the analyst unique advantages. This paper reviews the fundamental aspects of PED especially at microelectrodes, and its application in microchromatographic and electrophoretic separation techniques, including microchip devices.

Solid Electrodes in Electroanalytical Chemistry: Present Applications and Prospects for High Throughput Screening of Drug Compounds

“…Silver electrodes are used as a substrate for a mercury film. Moreover, it can be used as the electroactive electrode for the determination of low-soluble compounds [9,18]. Bismuth film electrodes have been shown to be an attractive alternative to mercury films used for specific stripping voltammetric techniques [19,20].…”

A review of pulsed electrochemical detection following liquid chromatography and capillary electrophoresis

“…LaCourse and Owens [53,54] were the first to introduce the use of IPAD coupled with a Au microelectrode following CE for the determination of amine and sulfur-containing compounds. Since then, numerous reviews have been published on the advances and applications of microelectrodes utilizing PED following aqueous-based separation systems [55][56][57][58].…”

Determination of Nonsteroidal Anti‐inflammatory Drugs in Serum by Microchip Capillary Electrophoresis with Electrochemical Detection

“…Other advantages of the use of PAD are signal stability, sensitivity comparable to (or better than) amperometry and the possibility of performing direct detection of analytes that are nonelectrochemically active by other techniques. [38,41,43,50,52,53] The PAD waveform was optimized so that maximum signal magnitude and stability were achieved. This was accomplished by generating hydrodynamic voltammograms (multiple injections of the same sample while varying the studied potential) as a function of each of the potential steps in the waveform.…”

“…However, this mode of detection suffers from the possibility of fouling the working electrode [35 -37]. Pulsed electrochemical detection (PED) has proven to be effective in overcoming problems associated with electrode fouling [38] and has been used for a large number of analytes including carbohydrates, amino acids, sulfur-containing compounds, alcohols and phenols [39 -42]. PED is accomplished by integrating a self-cleaning cycle with the amperometric measurement step in order to prevent buildup of oxidation products on the electrode surface.…”