Thin Layer-Based Spectral and Electrophoretic Study of Electro-Oxidation of Solid Ellagic Acid

Abstract

Acquisition of data from both in situ spectroscopy detection and online chromatography-like separation is important for studying complex electrochemical reactions. The present work provides an example of combination of thin-layer spectral and electrophoretic electrochemistry, both based on thin-layer electrolysis. Two thin-layer electrochemical cells were used to investigate the electro-oxidation of solid ellagic acid at different potentials, in acidic, physiological, and alkaline buffer media. UV-vis spectra and cyclic voltabsorptograms of the oxidation products were recorded in situ without interference from the solid reactant. Four oxidation products, depending upon the buffer pH and the applied potential, were separated and detected by electrophoretic electrochemistry. The major products possess redox stability, possibly with a diquinonemethide structure. The minor product is considered as an o-quinone derivative with a lactone-ring-opening, which can be reduced or further oxidized at appropriate potentials. A consecutive-parallel reaction mechanism is proposed for the formation of four products of ellagic acid in different pH media, which enriches the knowledge about the oxidation pathway and antioxidant property of this biologically active polyphenol compound.

Trace Fe Incorporation into Ni-(oxy)hydroxide Stabilizes Ni3+ Sites for Anodic Oxygen Evolution: A Double Thin-Layer Study

“…A thin-layer long-optical-path spectroelectrochemical cell was constructed for in situ characterizations of the thin-layer electrolyte, as shown in Figure S3. , The cell body is a standard square quartz cell with 10 mm optical path length. The three-electrode system is the same as in the voltammetric measurements, except that a miniature Ag/AgCl/KCl sat electrode is used due to the cell space limit.…”