Voltammetric Detection of Ascorbic Acid at Organic Conducting Polymers Electrodes and Flow Injection Analysis

Abstract

In this paper, a sensitive and rapid modified electrode for the determination of Ascorbic Acid (AA) is proposed. In this study, active compound AA was determined from commercial drug form based on electrochemical oxidation properties at various conducting polymer electrodes by voltammetric methods. Electrodes modified by the electrodeposition of conducting organic polymers such as poly(3-methylthiophene, PMT), polypyrrole (PPY) and polyaniline (PAN) were used as chemical sensors for voltammetric analysis and flow injection detection of AA. The electrochemical behavior of AA at conducting polymer electrodes was compared and the effects on behavior of electrolyte type and its pH and the film thickness were systematically examined. The results showed that the proposed modified surface catalyzes the oxidation of AA. Electrocatalytic efficiency decreases in order of PMT > PPY > PAN. Voltammetric peak positions were affected by the nature of the electrolyte and its pH. Also, the effect of increasing film thickness was to observe increased peak heights for oxidation potential of AA. The best results for the determination of AA were obtained by DPV in Na2SO4 (pH 2.0) and PMT electrodes. Polymer coated electrodes were also used in an amperometric detector for flow injection analysis of AA. The responses of the polymer electrode were 5–15 times larger as compared to those of bare platinum. PMT showed improved performance as an amperometric detector for flow injection analysis systems over other types of polymer electrodes. Detection limits as low as 1×10−9 M were achieved using the PMT, compared to 1×10−6 M using platinum electrodes.