Construção de eletrodos 3D empregando tintas condutoras modificadas com materiais nanoestruturados para determinação de nimesulida em amostras de fármaco, água de abastecimento e urina sintética

Abstract

The quantification of pharmaceutical compounds in different matrices, including environmental and biological samples, has received a lot of attention from the scientific community due to their impact on human health and the environment. This paper presents an electrochemical system for the determination of Nimesulide (NIM), a non-steroidal antiinflammatory drug, in water supply samples, synthetic urine and medicines. A disposable, lowcost electrode, with a maximum manufacturing cost of R$0.09 per sensor, was built and optimized, whose basic structure was a composite material (MC) immobilized on a 3D acrylonitrile butadiene styrene (ABS) support, for the determination of NIM in different samples. The composition of the sensor was optimized and different proportions of graphite and nail polish were evaluated in the production of the composite material. The surface of the electrodes was characterized using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIE) and cyclic voltammetry (CV). The sensor was applied for the quantification of NIM using square wave voltammetry (VOQ) and flow injection analysis with amperometric detection (FIA-AMP). The first method showed a linear range from 10.0 to 50.0 µmol L-1 , with a simple sample treatment, good precision (RSD < 3.4 %) and good detectability (detection limit of 0.018 µmol L-1 ). Samples were fortified at three concentration levels to assess the accuracy of the method, obtaining recovery values of 96 to 113 %. In addition, the sensor was modified by electrochemical treatment via VC in an alkaline medium with KOH, where the parameters of alkaline solution concentration, number of cycles and potential range were optimized. A second modification was then carried out, with the electrodeposition of silver nanoparticles (AgNP) using a Box-Behnken 3³ chemometric design. For the second method, the sensor showed good sensitivity (0.173 ± 0.002 µA L µmol-1 cm-2 ) and precision (RSD < 7%), as well as recovery values in the 92 to 104% range, a linear range of 5.0 to 25.0 µmol L-1 and a low detection limit of 0.81 µmol L-1 . Thus, both sensors were applied to the determination of NIM, showing concordant results at a 95% confidence level. The results obtained with these sensors were compared with high-performance liquid chromatography.