Development of Dual-Electrode Amperometric Detectors for Liquid Chromatography and Capillary Electrophoresis

Abstract

Abstract The body of this research was focused on the use and development dual-electrode detection schemes for liquid chromatography and capillary electrophoresis. These detection schemes were developed to investigate redox chemistries for endogenous and exogenous antioxidants that play key roles in maintaining tissue redox homeostasis under oxidative stress conditions. A parallel adjacent dual electrode detector was first proposed for liquid chromatography in which redox cycling was hypothesized to occur between the electrodes resulting in signal enhancement. Flow rates for these systems were too high (≥ 1.0 mL) to obtain redox cycling and subsequently no signal enhancement was observed for these systems. Flow rates in capillary electrophoresis are significantly lower compared to liquid chromatography. Therefore, a parallel dual–electrode was developed for capillary electrophoresis in this work. The dual–electrode was investigated using reduced phenolic acids, which were chemically reversible, semi–reversible and non-reversible compounds allowing all potential electrochemistry’s to be investigated. Redox cycling and signal enhancement was observed with the developed dual–electrode. Furthermore, the parallel dual–electrode could be operated in either a redox cycling mode or dual–potential mode, where either chemical reversibility or voltammetry could be used as a means to confirm migration based peak identification, respectively. The same design was then applied for a dual Au/Hg electrode for capillary electrophoresis, in which thiols and disulfides were investigated in vivo. With the developed dual Au/Hg electrode redox changes were observed as a result of chemically induced oxidative stress.