Abstract: The use of the electrode described previously (Anal. Abstr., 1990, 52, 4J112) for the oxidative detection of simple sugars has been extended. Cyclic voltammetric scans for the compounds showed a broad oxidation in the region of +0.4 to +0.6 V vs. Ag - AgCl. When used in flow injection analysis and LC, detection limits were in the pmol to nmol range. With flow injection the coefficient of variation (n = 60) for 10 µM-gluconic acid was 4.9% and in the analysis of a tobacco leaf extract by LC, the standard deviation, e.g., for 3.7% of glucose was 0.2%.

Abstract: A RuO2-modified carbon paste electrode (prep. described) was used in the constant-potential cyclic voltammetric flow detection of carbohydrates. Samples in 1 M NaOH were analyzed at the electrode (+0.4 V; 20 mV s-1) with Ag - AgCl and Pt-wire reference and auxillary electrodes, respectively. The effects of variables, viz, pH, flow rate, operating potential and surface 'loading', were studied. The method was applied in the detection of deoxyribose, fructose, galactose, gluconic acid, glucose, glycerol, lactose, maltose, ribose and sucrose (electrode responses are tabulated). Working ranges were from 0.1 to 10 mM glucose and 0.1 to 1 mM ribose, fructose and galactose. The detection limits were pmol-levels and the coefficient of variation (n = 72) was 1.2%. The electrode was stable for >48 h with a signal loss of 10% over this period.