Electrochemical behavior of codeine and its sensitive determination on graphene-based modified electrode

A new electrochemical sensor for codeine was fabricated based on composite graphene and Nafion film modified glassy carbon electrode. It was found that the electrochemical response of this sensor was greatly improved and displayed excellent analytical performance for codeine detection, which could be attributed to the high codeine loading capacity on the electrode surface and the outstanding electric conductivity of graphene. Under the optimized conditions at pH 4.0, the peak currents were linear relationship with codeine concentrations in the range of 5 × 10−8 to 9 × 10−6 mol L−1 and 9 × 10−6 to 3 × 10−5 mol L−1, using square wave voltammetry with a detection limit of 1.5 × 10−8 mol L−1. The proposed method was successfully applied to the determination of codeine in both urine samples and cough syrup.