Microdispositivos eletroquímicos confeccionados com caneta 3D e outros instrumentos portáteis e acessíveis para a análise de contaminantes ambientais

Abstract

The development of new low-cost electrochemical cells and sensors associated with the principles of Green Analytical Chemistry has been the objective of several research groups. In this thesis, miniaturized, practical and versatile electroanalytical devices were described for the determination of contaminants in environmental samples, using only portable and low-cost instruments (e.g., 3D pen, micro-grinder, scissors, tips, etc.). In the first chapter, the 3D pen is proposed as an alternative instrument to 3D printers for the manufacture of sensors, being used to extrude a commercial carbon black and polylactic acid (CB/PLA) conductive filament on phenolite substrates (copper board). Although manufactured by hand, the electrodes manufactured with a 3D pen showed electrochemical performance and manufacturing reproducibility comparable to a 3D printer (DPR < 20% vs 8% n = 10). As a proof of concept, calibration curves for model analytes in different electrochemical systems were constructed, such as Cd2+ and Pb2+ by square wave anodic redissolution voltammetry (SWASV), paracetamol by batch injection analysis with amperometric detection, and ascorbic acid by electrochemical voltammetry. square wave (SWV). In the second chapter, an electrochemical cell is proposed that contains three integrated electrodes (work, counter and pseudo-reference) printed with a 3D pen on the smallest micropipette tip (volume: 1 – 10L). The cell required a reduced sample volume (minimum of 10 μL) and proved to be very versatile, as it can be easily coupled with different commercial micropipette tips (manual and electronic) and used for stationary voltammetric measurements (measured after aspiration) and hydrodynamic (measured concomitantly with aspiration). These characteristics were demonstrated for the voltammetric detection of catechol, determination of catechol by stationary SWV and determination of Pb2+ by SWASV (pre-concentration step carried out during controlled aspiration of the solution) in tap water and artesian well water, with recoveries close to 100%. The manufacturing cost of the developed devices is very low (< R$ 0.50), as it uses low-cost instruments and requires minimal quantities of conductive filaments. The 3D pen proved to be a promising tool for manufacturing electrochemical devices, as it has a reduced cost compared to printers using fused deposition modeling (R$ 50 vs 1200), in addition to being simpler and more portable, allowing even more production decentralized and by anyone.