Voltammetric behavior of theophylline and its determination at multi-wall carbon nanotube paste electrode

The voltammetric behavior of theophylline was investigated using cyclic and differential-pulse voltammetric techniques. The cyclic voltammetric results indicate that multi-wall carbon nanotube paste electrode can remarkably enhance electrocatalytic activity toward the oxidation of theophylline in pH 3.0 phosphate buffer solution than the carbon paste electrode. The oxidation of theophylline was observed to be a two-electron process, irreversible with diffusion character. Effects of anodic peak potential (Ep), anodic peak current (Ip) and heterogeneous rate constant (ko) have been discussed. Under optimal conditions, the anodic peak current was proportional to theophylline concentration in the range of 2.0 × 10−6 to 1.5 × 10−4 M with a detection limit of 1.97 × 10−8 M using differential pulse voltammetry. The proposed method was employed to determine theophylline in pharmaceutical formulations and urine as a real sample.

MWCNT-PE is used for the oxidation of theophylline in phosphate buffer solution of pH 3.0 to study the influence of several physico-chemical parameters like potential, scan rate, pH and concentration.Figure optionsDownload as PowerPoint slideHighlights
► Multi-walled carbon nanotubes paste electrode has been successfully used for the electro-oxidation of TP in phosphate buffer solution (pH = 3.0).
► Cyclic and differential-pulse voltammetric techniques are used.
► Effects of Ep, Ip and ko have been discussed.
► Differential pulse voltammetric method with good precision and accuracy was developed for the determination of TP in pharmaceutical formulations and urine as a real sample.