Stencil-printed electrode using conductive graphite-based ink: a cost-effective approach for electrochemical determination of dipyrone

The global demand for simpler and faster analytical protocols to establish point-of-care devices has fueled the search for disposable sensors. In this context, these analytical platforms facilitate the monitoring of emerging pollutants, biomolecules, and pesticides at remote locations. Additionally, disposable sensors must possess sustainable production, affordability, fast and reliable response, and minimal sample treatment. Therefore, this paper presents the development of a low-cost sensor (US$ 0.13) used for the electrochemical monitoring of dipyrone (DIP). The sensor was constructed by screen-printing, using a vinyl stencil and a conductive ink made in the laboratory from graphite and alkyd resin (vitreous varnish). The composition of the conductive ink was optimized, and the stencil-printed electrodes (StPE) were properly characterized using imaging and electrochemical techniques. Square wave voltammetry (SWV) was applied for the determination of DIP in pharmaceutical formulation samples, achieving excellent detectability (detection limit of 0.819 µmol L^-1) and precision (RSD < 7%). The average percentage recovery ranged from 98 to 111%, thus indicating the good accuracy of the method. Additionally, the results indicated that the sensor is interference-free for molecules commonly present in pharmaceutical formulations and/or administered in conjunction with DIP. The results were statistically comparable to a reference technique, which allows us to assume that the proposed device has suitable characteristics for routine electroanalytical applications.