Fast‐pulsed electrochemical detection at noble metal electrodes: The frequency‐dependent response at gold electrodes for chromatographically separated carbohydrates

Abstract

Waveforms used in pulsed electrochemical detection (PED) have frequencies of ca. 1 Hz when optimized to give a maximum signal-to-noise ratio (SIN) for carbohydrates. However, higher frequencies are desired for applications of PED to capillary electrophoresis (CE) and microcolumn liquid chromatography (MLC), which can produce narrow elution peaks. Minimization of the time periods for oxidative cleaning and reductive reactivation in PED waveforms generated by the Dionex Pulsed Electrochemical Detector allows the increase in waveform frequency to ca. 3 Hz without change in the traditional time period of 200 ms, prescribed for integration of the anodic current. However, further increase in frequenq requires a decrease in the integration period with a corresponding loss of signal strength.

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

“…Roberts and Johnson [24,36] initially investigated oxide formation and dissolution kinetics at a Au electrode at basic pH in the anticipation of minimizing oxide growth to eliminate high background currents observed in Mode II detections. With their studies, Roberts and Johnson were able to deduce the origins of signal contribution as a result of surface oxide formation and dissolution.…”

Electrochemical detectors ? tailormade techniques for liquid chromatography and capillary electrophoresis?

“…Peak widths can be very narrow in CE, so that fast pulse waveforms as well as short measuring periods are required. Unfortunately, the increase in the waveform frequency leads to poorer detection limits [37]. Therefore, constant potential amperometric detectors would be preferable for CE.…”

Optimization of Response of the Silver Oxide Electrode for the Detection of Carbohydrates and Related Compounds

“…Various metals have been used, including gold, platinum, copper and nickel [1][2][3][4][5][6][7][8][9][10][11][12][13], in order to catalyze the electron transfer. Various metals have been used, including gold, platinum, copper and nickel [1][2][3][4][5][6][7][8][9][10][11][12][13], in order to catalyze the electron transfer.…”