Voltammetric determination of sulfanilamide using a cobalt phthalocyanine chitosan composite

In this paper, a composite based on chitosan and cobalt phthalocyanine immobilized onto a glassy carbon electrode is presented for the sensitive determination of sulfanilamide in pharmaceutical and urine samples. The modification performed on the electrode surface, by the deposition of this composite, exhibits an irreversible anodic peak at 0.97 V vs. Ag/AgCl, KClsat in phosphate buffer at pH 7.00 for sulfanilamide. Results show that peak potential is influenced linearly by the pH of the supporting electrolyte, exhibiting a slope of 0.054 V/pH. Using differential pulse voltammetry, detection of sulfanilamide was possible in a linear range from 1.00 to 53.00 mu mol dm(-3) with a detection limit and quantification limit of 0.27 and 0.91 mu mol dm(-3), respectively. Importantly, the sensor showed practical applications as an analytical tool for the quantification of sulfanilamide in pharmaceutical formulations and urine samples. The electrochemical approach detailed here has been validated to drug samples using a spectrophotometric method. The method proposed presents good linearity, low quantification and detection limits being of excellent applicability in pharmaceutical and urine samples.