Determination of Copper in Cachaça Samples Preconcentrated on Filter Paper by Portable EDXRF

Cachaça is a distilled beverage made from sugar cane and is the most consumed spirit in Brazil. Among the inorganic elements present in this drink, copper stands out due to its potential harm to human health, which necessitates continuous quality control. In this context, the objective of this study was to develop an analytical method for the determination of copper in artisanal cachaça samples using preconcentration on a paper support and detection by portable X-ray fluorescence spectrometry (pXRF). For the analytical measurements, samples were preconcentrated on commercial filter paper using a volume of 120 μL and a temperature of 120 °C. The method was evaluated through figures of merit such as linear range (2 to 10 mg L^-1), correlation coefficient (0.99661), detection limit (0.31 mg L^-1), and quantification limit (0.93 mg L^-1). The method demonstrated acceptable analytical precision, with repeatability and reproducibility values below 6.0%, and good accuracy, with recovery rates between 91.4% and 109.9%. Application of the method to different commercially available cachaça brands showed that copper concentrations did not exceed 2.5 mg L^-1. Therefore, considering the preconcentration efficiency and the figures of merit, the method proved to be promising for copper analysis in artisanal cachaças, being fast, environmentally friendly, and low-cost, making it suitable for practical applications, such as use by small producers or for regulatory inspections.