Simultaneous Determination of Ascorbic Acid and Uric Acid in Blood Serum Using an Overoxidized Polypyrrole Film Modified Glassy Carbon Electrode

Abstract

The present study reports the simultaneous determination of ascorbic acid (AA) and uric acid (UA) at pH = 7.0 using an overoxidized polypyrrole (OPPy) modified glassy carbon electrode (GCE). The bare GCE does not separate the voltammetric signals of AA and UA, whereas OPPy-modified GCE not only can completely separate the overlapped oxidation peaks of AA and UA but also dramatically enhances their oxidation currents compared with the bare GCE. Factors influencing determination including pH and scan rate were optimized. A linear response was observed in the concentration range from 7.7 × 10−7 to 2.1 × 10−5 M and 3.8 × 10−5 to 1.1 × 10−3 M with a correlation coefficient of 0.998 and 0.999 for UA and AA, respectively. The detection limit calculated was 7.2 × 10−7 for UA and 1.6 × 10−5 M for AA. The relative standard deviations (R.S.D.) for the oxidation of 7.5 × 10−4 M AA and 5.0 × 10−5 M UA are 3.5% and 1.1%, respectively. The application of the modified electrode was demonstrated by measuring the concentration of UA and AA in human blood serum.