Simultaneous Quantification of Gallic and Caffeic Acid in Red Wine Using Differential Pulse Voltammetry Assisted by Chemometrics

Abstract

This article explores the application of multivariate curve resolution with alternating least squares for the simultaneous determination of gallic acid and caffeic acid on the surface of a glassy carbon electrode without additional modification. Gallic acid and caffeic acid are primary polyphenols in red wine, and their electrochemical signals overlap significantly, making simultaneous quantification challenging without additional experiments like electrode modification or alternative analytical techniques beyond differential pulse voltammetry. The study successfully quantified these compounds in complex mixtures by generating second-order data from differential pulse voltammetry experiments conducted at various potential steps and subsequently applying multivariate curve resolution with alternating least squares. The use of constraints during optimization prevented rotational ambiguities common in this modeling, leading to unique results in validation samples. The limits of detection found for gallic acid (LOD 1.6) and caffeic acid (LOD 7.6) are in excellent agreement with the expected concentrations of these compounds in red wines. Advantages such as simplicity, low cost, and speed, as no electrode modification is required, coupled with excellent results obtained for real samples, represent a promising alternative for polyphenol analysis in the wine industry.