Development and characterization of anodically initiated luminescent detection for alcohols and carbohydrates

We have developed and characterized a novel detection method for hydroxyl compounds with no pi-electron resonance structure, such as alcohols and carbohydrates. The proposed method is based on luminescence, initiated by electro-oxidation of their hydroxyl group at a glassy carbon electrode in alkaline aqueous solution. The luminescence is elicited when a proper excitation potential is applied to the electrode and its intensity is proportional to the concentration of hydroxyl compounds. The luminescence has been applied successfully to a how-through detection for hydroxyl compounds. In the flow-through system, a constant potential procedure is employed to trigger the luminescence. The sensitized fluorescence, triggered by the presence of a suitable fluorescer (fluorescein), is utilized to detect hydroxyl compounds in pmol amounts. With a variety of hydroxyl compounds, double logarithmic plots of luminescence intensity vs. concentration give a linear relationship in the tested range of 10 mu M to 1 mM. The limits of detection for alcohols (including methanol) and carbohydrates are estimated to be in the range from about 10 pmol to nmol per 50 mu l injection (signal-to-noise ratio of 3).