Plataformas eletroquímicas de baixo custo produzidas em laboratório para a determinação de antibióticos em matrizes farmacêuticas, alimentares e ambientais

Abstract

The development and application of simple, rapid, and low-cost electroanalytical platforms are essential for the determination of antibiotics in various sample matrices. In this study, three distinct approaches were proposed and evaluated for the quantification of antibiotics in pharmaceutical, food, and environmental samples, focusing on strategies that combine selectivity, sensitivity, and operational feasibility. In pharmaceutical analysis, the batch injection analysis with amperometric detection (BIA-AD) technique was employed using a boron-doped diamond (BDD) electrode for the sequential determination of amoxicillin (AMX) and potassium clavulanate (CLA). The analytical strategy involved the application of two sequential potential pulses (+1.3 V and +1.8 V), enabling selective quantification of AMX at +1.3 V and oxidation of both (AMX + CLA) at +1.8 V. The oxidation current of CLA was obtained by subtraction, using a correction factor. The method showed high analytical throughput (>200 injections/hour), excellent precision (RSD < 1.3%), and detection limits of 0.31 μmol·L⁻¹ for AMX and 1.99 μmol·L⁻¹ for CLA. In food analysis, a disposable electrode composed of graphite, glass varnish, and acetone was developed for the detection of sulfamethoxazole (SMX) in milk. Selectivity and stability were enhanced by using two detection potential pulses (+1.0 V and +1.3 V) and two cleaning potential pulses (+1.5 V and −1.5 V). The method showed good linearity (1.0–50.0 μmol·L⁻¹), a detection limit of 0.31 μmol·L⁻¹, and recoveries of 68 ± 7%, 103 ± 7%, and 115 ± 7% for milk samples fortified with 5.0, 10.0, and 20.0 μmol·L⁻¹ of SMX, respectively. For environmental monitoring, a voltammetric approach was developed for the indirect detection of AMX in water using disposable sensors fabricated by additive manufacturing (3D printing). The strategy involved three sequential steps: (i) chemical and electrochemical activation of the 3D electrode in alkaline medium, (ii) preconcentration of AMX by adsorption onto the electrode surface, and (iii) detection via oxidation of adsorbed AMX, followed by reduction and reoxidation of the oxidized product (quinone). The differential pulse voltammetry (DPV) technique enabled a detection limit of 0.01 μmol·L⁻¹, with high selectivity against evaluated interferents and recoveries ranging from 82 to 106% in different water types. All three approaches demonstrated robust analytical performance, operational simplicity, low cost, and strong potential for portability, highlighting the effectiveness of electrochemical platforms as tools for routine applications in quality control, food safety, and environmental surveillance.