GENERATION OF SECOND-ORDER ELECTROCHEMICAL DATA FOR INTERFERENCE-FREE CALIBRATION OF GALLIC ACID IN RED WINES

MONTEMERLO, ANTONELLA; AZCARATE, SILVANA MARIELA; CAMIÑA, JOSÉ MANUEL; MESSINA, GERMAN

Congreso; 5. 20th ENQA ? Brazilian Meeting on Analytical Chemistry and 8th Congresso iberoamericano de Química Analítica; 2022

Wine consists of a solution of ethanol in water, which also contains a variety of organic compounds,such as organic acids, amino acids, sugars, volatile compounds and polyphenols in differentconcentrations. In particular, the interest in the latter is continuously growing due to its bioactivenature and its close relationship with the final qualities of the resulting product. Specifically, gallicacid is one of the most widely used phenolic compounds as a marker for the characterization of wineproducts. The use of sulfur dioxide is a common practice in oenology that is currently consideredessential for the correct finish of wines. However, there is a growing concern about the reduction ofits levels in the final product, which makes it necessary to search for complementary agents. Amongthe possible alternatives is ascorbic acid or vitamin C. In recent years, its use as an additive forwinemaking has been reported due to its antioxidant properties, its reducing nature and because itis a healthy compound. It is important to note that ascorbic acid will never replace the use of sulfites,but it can be an excellent complement to it. The rise of multidirectional calibration enabled thequantification of numerous analytes in complex samples without interference, even in the presenceof components not modeled in the calibration, commonly referred to as a second-order advantage.However, classical chemometric methodologies assume that the data comply with the property ofbilinearity, which is sometimes not possible to achieve with all instrumental methods. Among them,electrochemistry is capable of providing information with high potential to be used in the developmentof novel second-order calibration methodologies, although they may not meet the aforementionedconditions. This work raises the possibility of developing a simple and versatile methodology for theinterference-free quantification of gallic acid in the presence of ascorbic acid, based on chemometricmodeling of electrochemical data. Second-order data were generated by cyclic voltammetry (CV) atdifferent scanning speeds and various modeling strategies were implemented to treat the dataobtained. The quantification of gallic acid in the presence of ascorbic acid was possible using amodel based on the resolution of multivariate curves-alternating least squares (MCR-ALS). It wasfound that the optimal number of estimated components for calibration is equal to one. While theanalytical figures of merit found, REP% 9.4, LOD 6.094x10-5 mol L-1, show the possibility of usingthis methodology for the quantification of gallic acid in complex samples. The studies carried outopen the doors for wine quality analysis through new and innovative methodologies based on thepotential of electrochemical data, combined with chemometric techniques, which make it possible toobtain results in a simple, fast and reliable way for quality control in the wine industry.