ascorbic-acid and ruthenium-tetraoxide

This paper reports that the high electrocatalytic activity of RuO2 nanowires grown on electrospun TiO2 nanofibers for the oxidation of l-ascorbic acid (AA); and the application of these materials for direct selective sensing of AA in complex samples. Compared to bare glassy carbon (GC) electrode, RuO2 nanowires on TiO2 nanofibers-loaded GC electrode facilitates the oxidation of AA most drastically among the tested species: AA, 4-acetamidophenol (AP), dopamine (DA), uric acid (UA), and glucose. The amperometric response of RuO2 nanowires on TiO2 nanofibers at the applied potential of 0.018 V (vs. SCE) exhibits high sensitivity (268.2 ± 3.7 μAmM(-1)cm(-2), n=5), low detection limit (<1.8 μM), great linearity, reasonable stability, and exclusive selectivity over AP, DA, glucose and UA at their physiological levels. In differential pulse voltammetry, it is verified that the potential resolution of RuO2 nanowires on TiO2 nanofibers is able to differentiate AA, DA, UA, and AP one from the others. In addition, as prepared RuO2 nanowires on TiO2 nanofibers are successfully applied for direct and selective AA measurements in commercial vitamin samples and for the real-time direct analysis of AA generated from living rat liver tissue in vitro.

Topics: Adsorption; Animals; Ascorbic Acid; Computer Systems; Conductometry; Electroplating; Equipment Design; Equipment Failure Analysis; Liver; Male; Nanofibers; Nanowires; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Rotation; Ruthenium Compounds; Sensitivity and Specificity; Tissue Distribution; Titanium

The anodic oxidation of ascorbic acid on a ruthenium oxide hexacyanoferrate modified electrode was characterized by cyclic voltammetry. On this modified surface, the electrocatalytic process allows the determination of ascorbic acid to be performed at 0.0 V and pH 6.9 with a limit of detection of 2.2 microM in a flow injection configuration. Under this experimental condition, no interference from glucose, nitrite and uric acid was noticed. Lower detection limit values were obtained by measuring flow injection analysis (FIA) responses at 0.4V (0.14 microM), but a concurrent loss of selectivity is expected at this more positive potential. Under optimal FIA operating conditions, the linear response of the method was extended up to 1 mM ascorbic acid. The repeatability of the method for injections of a 1.0 mM ascorbic acid solution was 2.0% (n=10). The usefulness of the method was demonstrated by an addition-recovery experiment with urine samples and the recovered values were in the 98-104% range.

Topics: Ascorbic Acid; Catalysis; Electrodes; Ferrocyanides; Flow Injection Analysis; Ruthenium Compounds