Abstract
The development of fast, reliable, and cost-effective techniques for pharmaceutical compound analysis is an issue of paramount importance to the pharmaceutical industry, environmental sciences, and many other applications. In this work, a low-cost graphite sheet electrode (GSE) was used as a disposable working electrode. To this purpose, the GSE surface was subjected to a cold plasma discharge using a mixture of argon and O(2). The sensor was applied to dipyrone (DIP) quantification. Initially, the influence of pH on the electrochemical response of DIP on the pyrolytic graphite sheet (PGS) electrodes was evaluated using a 0.12 mol L(-1) Britton-Robinson buffer solution at pH values ranging from 2.0 to 12.0. The solution adjusted to pH 4.0 was selected as the supporting electrolyte for the experiments since a larger current intensity was obtained at this medium. The mass transport of DIP toward the PGS surface was investigated by cyclic voltammetry, evidencing a diffusion-controlled process. DIP was initially quantified by square wave voltammetry (SWV) with a linear range of about 2.5-200 μmol L(-1) and a calculated limit of detection of about 0.31 μmol L(-1). Finally, SWV was used to enable DIP detection in synthetic urine solutions, demonstrating its applicability as a sensor tool in real analysis.