Electrochemical behavior and voltammetric determination of theophylline at a glassy carbon electrode modified with graphene/nafion.

An ultrasensitive voltammetric sensor, a simply coated graphene-Na?on suspension on a glass carbon electrode surface, was fabricated and used to investigate the electrochemical behavior of theophylline as described in the present paper. The results indicated that this voltammetric sensor exhibited a special recognition capacity to determine theophylline as well as having high sensitivity due to the excellent characteristics of graphene and the adsorption action of Nafion for theophylline. Under the selected condition using differential pulse voltammetry, the response peak currents had a linear relationship with the theophylline concentrations in two ranges from 1.0 × 10(-8) - 1.0 × 10(-6) and 2.0 × 10(-6) - 3.0 × 10(-5) mol L(-1) with a low detection limit of 6.0 × 10(-9) mol L(-1). Moreover, according to the results obtained in the analysis of theophylline in two standard samples, it demonstrated the applicability of present method into real sample determination.