Determination of Ascorbic Acid by a Composite-Modified Platinum Electrode.

Thin composite layers of poly(3,4-ethylenedioxythiophene) and poly(4-lithium styrene sulfonic acid) were formed on a platinum surface. The modified electrode platinum/polyethylenedioxythiophene:poly(4-lithium styrene sulfonic acid) was characterized by cyclic voltammetry, chronocoulometry, and electrochemical impedance spectroscopy. The results showed that the electrode may be used as a working electrode for electroanalytical methods. This electrode was used for the determination of ascorbic acid. The effect of composite layer thickness on the functionality of the electrode was characterized for ascorbic acid determination. Another investigated aspect was the process of ascorbic acid oxidation in solutions of various pH values. The results showed that the modified electrode was suitable for the determination of ascorbic acid in various electrolytes from pH 2 to 7.6 in the presence and absence of buffer solutions. The linear dynamic range of ascorbic acid concentrations corresponded to its concentrations in physiological fluids. [ABSTRACT FROM PUBLISHER]