A Continuously Renewed Copper Electrode for Constant-Potential Amperometry
Abstract
Pulsed amperometric detection (PAD) is a well-established technique used for the detection of electroactive compounds following Ion Chromatography (IC). Target analytes, such as carbohydrates and amino acids, typically have no suitable chromophores and are not detectable by suppressed conductivity following IC separation. While direct current (DC) amperometry is simpler, the formation of oxidation products quickly fouls the electrode surface; PAD removes these products extending electrode longevity for up to ~2 weeks of operation. To further extend electrode lifespans, a new strategy is introduced herein using DC amperometry on a sacrificial copper wire anode. The wire face continually dissolves under oxidative conditions while a spring-loaded plunger feeds the wire into a cell so that the interelectrode distance between the wire working electrode (WE) and counter electrode (CE) is maintained. High nanomolar (sub-ppm) limits of detection have been quantified for simple sugars, and with the use of internal standards the electrode has demonstrated virtually no loss of signal over 2 weeks of continual operation.