Sensores eletroquímicos de grafeno induzido por laser: aplicações na detecção de resíduos de glifosato

Abstract

The thesis was structured as a literature review and two scientific articles. The review contextualized the use of agrochemicals in the Brazilian scenario, focusing on glyphosate, and emphasized the importance of monitoring these residues. It addressed the evolution of materials for application in electrochemical sensors, as well as the basic concepts of their functioning. Finally, it emphasized the use of electrochemical sensors for monitoring glyphosate residues. The first article reviewed advancements in the synthesis of Laser-Induced Graphene (LIG), initially developed with polyimide, but now exploring a wide range of materials, including synthetic polymers and biomass. It also explored the types of lasers utilized and modification methods, such as drop-casting and electrodeposition, which are employed to enhance the performance of LIG-based sensors by adjusting their electrochemical properties for various sensing applications in agriculture. The article highlighted LIG as a substrate for sensor platforms in the detection of metallic and organic pollutants, nitrate detection in soil, and leaf moisture, demonstrating its contribution to more sustainable agricultural practices. The second article detailed the development of an LIG sensor for glyphosate detection in drinking water, presenting promising results with detection and quantification limits of 2.7 μmol L⁻¹ and 9.0 μmol L⁻¹, respectively. The electrochemical characterization demonstrated a well-defined irreversible oxidation peak, while morphological and structural analysis revealed a foam-like porous structure with high surface area and crystalline parts. Raman analyses exhibited typical characteristics of graphene material. Selectivity tests showed good resistance to common interferents, and tests with drinking water samples indicated a reduction in detection capability at low concentrations. In conclusion, the developed LIG sensors proved to be a viable and cost-effective alternative for glyphosate detection, with potential application as sample pre-screening systems. Furthermore, the possibility of fabricating LIG from biodegradable natural polymers adds a sustainability dimension to these sensors. This not only reduces environmental impact but also aligns with the growing demands for more environmentally friendly agricultural technologies.