PLATINUM GLASSY-CARBON ELECTRODE AS DETECTOR FOR LIQUID-CHROMATOGRAPHIC DETERMINATION OF HYDROXYL-CONTAINING COMPOUNDS

A platinum-modified glassy carbon electrode was investigated as an amperometric sensor for the determination of alcoholic species in acidic medium. The described electrode was tested in liquid chromatography and flow-injection analysis by pulsed amperometric detection. It showed a promising combination among catalytic activity, detection limits and reproducibility for the determination of alcoholic species. The electrode response was stable; over 8 h a signal loss of less than 5% was observed. Linear responses at low concentrations yielded detection limits in the 0.6-1.8 mu g ml(-1) ranges for the various aliphatic alcohols. Typical relative standard deviations were comprised between 1.2% and 3.8% for all mono- and polyhydric compounds investigated. Linear plots of 1/I-p, and 1/C indicated Langmuir-type adsorption of analytes on the electrode surface. The Pt chemically modified electrode showed a few important differences with the bulk platinum electrode: i.e., a greater extension of linear range for relatively high concentrations and different trend of sensitivity towards the catalytic oxidation of mono-and polyhydric species.