Investigation of the electrochemical behavior and voltammetric determination of furfural in food samples using a solid amalgam electrode

Abstract

Process contaminants are undesirable chemical by-products that arise because of food processing steps such as heating, drying and fermentation. These contaminants can be present in both artisanal produced and industrialized foods, and their presence is related to the processes necessary and essential for their preparation, making it considerably difficult to avoid their presence, so it is recommended to at least control their concentration in the final composition. Although not all process contaminants are toxic, and some are even considered congeners in certain concentrations, certain types have been associated with possible health problems. Furfural, also known as 2-furaldehyde, is one such process contaminant, formed by pentose hydrolysis reactions during food processing and storage. Its toxicity is due to its ability to be absorbed through the skin, oral cavity, dermal contact, and inhalation, making it necessary to control its daily intake or regulate its presence in food. Acute exposure to furfural can cause liver and kidney damage, as well as promoting the development of tumors and mutations. Detecting furfural in processed foods usually requires the use of chromatographic techniques, which involve pre-concentration steps that can be time-consuming and expensive, as well as generating toxic residues. Electroanalytical methods have emerged as favorable alternatives due to their rapid results, operational simplicity, and good cost-benefit ratio. These methods have high sensitivity and can be easily used to determine furfural, even in complex samples such as processed foods. In this specific study, an electroanalytical technique was developed to explore the electrochemical behavior of furfural and determine its electroanalytical properties. The reduction and oxidation reactions at the polished solid silver amalgam electrode (p-AgSAE) were investigated using square wave voltammetry (SWV). Furfural exhibited two voltammetric peaks for reduction and three peaks for oxidation in a basic solution. The intensity and position of these peaks were influenced by the composition of the support electrolyte. The oxidation reactions showed the finest reproducibility and sensitivity of the signals, leading to experimental and voltammetric optimization. The optimum conditions included the use of a 0.04 mol L-1 Brinton-Robinson buffer (pH 12.0), a pulse potential frequency of 100 s-1, a pulse amplitude of 50 mV and a scan increment of 2 mV. Within the potential range of -1.8 V to 0 V, the electrochemical redox process of furfural occurred in three steps, resulting in the rapid and reversible formation of an anion radical that could be involved in dimerization and subsequent chemical reactions. Analytical parameters such as linearity range, equation of analytical curves, coefficients of determination, detection and quantification limits, recovery efficiency and relative standard deviation for intraday and interday experiments were evaluated using appropriate mathematical modeling. The data indicated that the proposed procedure is suitable for the analysis of furfural in processed food samples. The proposed methodology was applied to samples of alcoholic beverages (cachaça, cognac, rum, whisky, and aperitifs soft drinks), non-alcoholic beverages (pasteurized grape and orange juices), honey from different flowers, baby food, and dairy products (dairy flour, fermented milk, and powdered milk).