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 solut ions 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- an d polyhydric alcohols separated by liquid chromatography. A mechanisti c electrooxidation model is proposed that involves a Langmuir-type ads orption process on different sites: NiO and NiOOH for polyhydric and m onohydridic compounds, respectively. The process is followed by a hydr ogen abstraction from the carbon a to the OH group through a radical p athway in the rate-determining step. Constant-potential amperometric d etection was applied either after an anion-exchange chromatography wit h alkaline mobile phase or a size exclusion separation with a postcolu mn addition of alkaline solution. Examples of applications, which incl ude the separation and detection of simple alcohols present in real sa mples, are given.