ELECTROCATALYTIC OXIDATION AND LIQUID-CHROMATOGRAPHIC DETECTION OF ALIPHATIC-ALCOHOLS AT A NICKEL-BASED GLASSY-CARBON MODIFIED ELECTRODE

The electrocatalytic oxidation of aliphatic alcohols in alkaline solutions at a nickel-based chemically modified glassy carbon electrode (Ni-CME) was investigated. The electrode was characterized by voltammetry and flow injection and applied for amperometric detection of mono- and polyhydric alcohols separated by liquid chromatography. A mechanistic electrooxidation model is proposed that involves a Langmuir-type adsorption process on different sites: NiO and NiOOH for polyhydric and monohydridic compounds, respectively. The process is followed by a hydrogen abstraction from the carbon a to the OH group through a radical pathway in the rate-determining step. Constant-potential amperometric detection was applied either after an anion-exchange chromatography with alkaline mobile phase or a size exclusion separation with a postcolumn addition of alkaline solution. Examples of applications, which include the separation and detection of simple alcohols present in real samples, are given.