Desenvolvimento e fabricação assistida por impressão 3D de sensor eletroquímico modular à base de grafite reciclado e modificado com cobre para detecção de glifosato em cerveja

Abstract

Glyphosate is a widely used herbicide in agriculture, and its potential occurrence in food and beverages has driven the development of simpler, more accessible, and sustainable analytical methods. This study aimed to develop a modular electrochemical platform for the analysis of glyphosate in beer samples using graphite rods recovered from discarded zinc–carbon batteries and components fabricated by 3D printing. The modular graphite electrode, designated GR-E, was designed with a removable electroactive region, allowing its characterization before and after surface modification. The electrode surface was modified by copper electrodeposition, exploiting the interaction between glyphosate and copper species as an indirect recognition strategy for the analyte. Surface characterization by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy provided complementary information on the morphological, elemental, and structural changes promoted by the modification. The influence of pH was investigated, and a 0.1 mol L⁻¹ phosphate buffer at pH 5.0 was selected for the analytical studies. The electrochemical response of the GR-E-Cu electrode was evaluated by differential pulse voltammetry, showing a linear relationship between the integrated peak area and the decimal logarithm of glyphosate concentration over the range of 1.0 × 10⁻⁸ to 1.0 × 10⁻⁴ mol L⁻¹, with a coefficient of determination (R²) of 0.9958. The limits of detection and quantification were estimated at 0.597 and 1.811 μg L⁻¹, respectively. When applied to nine commercial beer samples, one sample exhibited a response above the limit of quantification, whereas the remaining samples showed signals between the limits of detection and quantification, allowing analyte detection but not reliable quantification. The results demonstrate the feasibility of the proposed platform as a modular, sustainable, and low-cost strategy for electrochemical analysis. However, matrix effects associated with beer samples indicate the need for further studies on selectivity, recovery, and analytical validation.