PULSED ELECTROCHEMICAL DETECTION AT NOBLE-METAL ELECTRODES IN LIQUID-CHROMATOGRAPHY

The direct electrochemical detection of numerous polar aliphatic compounds is achieved at Au and Pt electrodes under the control of multistep potential-time waveforms. In this technique, called "Pulsed Electrochemical Detection (PED)," the waveforms manage the sequential processes of sampling the faradaic signal, from the oxidation of analyte, followed by oxidative cleaning and reductive reactivation of the electrode surfaces. The response mechanisms in PED are strongly influenced by surface properties of the electrode s and, therefore, members of each chemical classification detected are observed to produce virtually identical voltammetric response. Consequently, applications of PED have their greatest analytical significance when coupled with Liquid Chromatography (LC) to achieve a priori resolution of complex mixtures. The basic concepts of PED are reviewed and LC-PED results are presented for a variety of samples containing mixtures of alcohols, carbohydrates, alkanolamines, amines, and sulfur compounds.