FAST-PULSED ELECTROCHEMICAL DETECTION AT NOBLE-METAL ELECTRODES - THE FREQUENCY-DEPENDENT RESPONSE AT GOLD ELECTRODES FOR CHROMATOGRAPHICALLY SEPARATED CARBOHYDRATES

Waveforms used in pulsed electrochemical detection (PED) have frequencies of ca. 1 Hz when optimized to give a maximum signal-to-noise ratio (S/N) 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 frequency requires a decrease in the integration period with a corresponding loss of signal strength.