Electroanalysis of theophylline at eriochrome black –T and graphite powder composite electrode

In this study, a selective, simple, and sensitive electrochemical method for the determination of theophylline was proposed based on a composite electrode. Electrochemical analysis of organic drug molecule, theophylline (TP) was investigated at eriochrome black-T and graphite powder composite electrode using different voltammetry techniques. The linear response was obtained in the range of 1.0 × 10−4 M to 10 × 10−8 M with a detection limit LOD 20 nM. A possible electrochemical oxidation for theophylline involving two electrons and two protons was found and a suitable mechanism was proposed. For the analytical applications, pharmaceutical dose form and human urine sample analysis were performed. Various interferents were used to investigate the interference in the analytical application, and it was found that the proposed method could be well adopted for clinical trials and real sample analysis.