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.

KEY WORDS: Cyclic voltammetry, Differential pulse voltammetry, Theophylline, 4-Amino-3-hydroxynaphthalene sulfonic acid

Bull. Chem. Soc. Ethiop. 2012, 26(1), 73-84.

DOI: http://dx.doi.org/10.4314/bcse.v26i1.8