Differential pulse voltammetric determination of theophylline at poly(4-amino-3-hydroxyl naphthalene sulfonic acid) modified glassy carbon electrode

Abstract

A glassy carbon electrode (GCE) was modified with electropolymerized film of 4-amino-3- hydroxynaphthalene sulfonic acid (AHNSA) in 0.1 M HNO3. Cyclic voltammetry (CV) was used to study the electrochemical properties of the polymer film. The polymer film-modified electrode was used to electrochemically detect theophylline (TP) in drug samples. The polymer-modified electrode showed excellent electrocatalytic activity for the oxidation of TP. Under optimal experimental conditions, there was a good linear relationship between anodic peak current and TP concentration in the range from 1.0 x 10-6 to 1.0 x 10-4 M with the correlation coefficient of 0.9983 and a detection limit of 4.7 x 10-8 M (S/N = 3 for n = 6). The application of the polymer-modified GCE for the determination of TP in drug formulations showed good recovery and reproducible results. © 2012 Chemical Society of Ethiopia.