Construção de dispositivos portáteis para determinação de conservantes e contaminantes em bebidas utilizando impressão 3D, spot tests e tratamento de imagens digitais

Abstract

In recent years, the development of colorimetric methods has gained attention again. This is due to the popularization of electronic devices for digital images acquisition, these devices are shown to be promising substitutes for the spectrophotometer, classic equipment used for colorimetric measurements. The use of digital images to perform colorimetric measurements enables the development of low-cost methods. To enable the miniaturization and development of portable platforms, it is possible to employ paper-based analytical devices as a reaction platform. The development of analytical methods for food quality control is very important to ensure quality parameters and detect possible contaminants. In this sense, the proposed work aims to develop two low-cost analytical methods to assess the presence of contaminants and ensure quality parameters in beverages. The first method aims to determine copper in sugarcane spirits samples using paper-based analytical devices. The use of paper as a reaction platform made it possible to use the Na-DDTC reagent, which in solution would need an extraction step with the appropriate solvent. The proposed method has a limit of quantification of 3 mg L-1, linear range 3 – 25 mg L-1 with R2 >0.99, precision (n = 10) 2.9%. When the method was applied to sugarcane spirit samples, it presented recovery values from 90.1 to 109.5%, showing that it is possible to apply the proposed method in samples of cachaça. The second method aims to determine sulfite in concentrated juice samples using paper based analytical devices, in addition to using the 3D printing technique to enable the construction of a platform to carry out the gas diffusion micro extraction (GDME) step. digital images to evaluate the colorimetric reaction were obtained by applying a smartphone (Galaxy S20+). The method has a quantification limit of 5 mg L-1, linear range 5 – 90 mg L-1 with R2>0.99; precision (n = 5) 2.2%. And when applied to analysis of concentrated juice samples, it showed excellent recovery value of 106.9%. Showing that it is possible to apply the proposed method to perform sulfite measurements in concentrated juice samples.