DEVELOPMENT AND CHARACTERIZATION OF A TITANIUM DIOXIDE-BASED SEMICONDUCTOR PHOTOELECTROCHEMICAL DETECTOR

The development and characterization of a flow-through semiconductor-based titanium dioxide photoelectrochemical detector for flow injection analysis and liquid chromatography is described. The detector is nonselective, responding to a variety of organic analytes including amines, aromatic alcohols, hydroquinones, aldehydes, and furans with redox potentials less positive than the valence band edge of the titanium dioxide semiconductor. An investigation of the illuminated photoelectrochemistry and dark semiconductor electrochemical properties of the detector was carried out as a function of solvent system, electrochemical potential, and TiO2 production variables. Illumination intensity, titanium oxidation temperature, and electrode potential controlled the magnitude of the photoelectrochemical currents. Duration of thermal oxidation and the amount of hydrogen doping determined the ratio of the light to dark current for the analyte. Linearity over 2 orders of magnitude and detection limits in acetonitrile of 40 and 140 pmol, for p-aminoacetanillide and diethylamine, respectively, were demonstrated. Illumination of the semiconducting TiO2 wire electrode along a cylindrical electrochemical cell indicated the possible application of this spatially-resolved detection technique to whole column detection chromatography.