Electrochemical determination of theophylline on a glassy carbon electrode modified with reduced graphene oxide-sodium dodecyl sulfate-Nafion composite film

An electrochemical sensor based on glassy carbon electrode modified with reduced graphene oxide-sodium dodecyl sulfate-Nafion* composite film was constructed and used to determine theophylline. The synthesized graphene oxide and surface morphology of the reduced graphene oxide-sodium dodecyl sulfate-Nafion film were characterized using IR spectroscopy, X-ray diffraction studies, and electrochemical impedance spectroscopy. The electrochemical behavior of the theophylline on the modified electrode was investigated using cyclic voltammetry and adsorptive differential pulse voltammetry. Under optimized analytical conditions, the electrode showed a linear response at concentrations of theophylline of 0.01–0.10, 0.1–1.0, and 1.0–40 µmol L−1 with the detection limit of 5 nmol L−1.