| Abstract: | Abstract Differential double-layer capacitance measurements applied to the silver-aqueous interface may serve as the basis of detection for surface-active ions in ion chromatography. There is a caveat to this approach, though, and that is that the electrode is subject to gradual fouling due to the accumulation of adsorbed matter. We report here on the incorporation of potential pulsing sequences to counter this damaging effect. Two approaches have been taken: 1) inclusion of a periodic potential cleaning pulse in the conventional, fixed-potential double-layer capacitance measurement scheme, and 2) utilization of a potential-pulse/coulometric measurement technique. the potential-pulse/coulometric procedure entails measurement of the change in charge required to charge the electrical double layer in response to specific adsorption of analyte. Its response-concentration behavior is similar to that observed for differential capacitance detection. the use of a combined, dual-potential (sequential) capacitive/amperometric detection scheme that provides unique complementation to either amperometric or capacitance detection is also discussed. |
