Method for quantifying catechin in a strawberry extract by measuring optical absorbance, at high sensitivity, under...

Catechin is considered a powerful antioxidant, and its rapid quantification could help urgently prevent inflammatory and coronary heart diseases. Consequently, the UV-Vis absorption spectrophotometry assay technique could serve this need for rapid detection. For this reason, we have carefully studied the possibility of dosing this antioxidant found in strawberry extract with precision, despite its chemical complexity. In the dosage technique used; sometimes the dilution of the solutions could be the way to resolve a specific quantification problem such as catechin in strawberry extract. This is quite particular, when the optical extinction coefficient of the target substance is very low compared to the extinction coefficients of the other chemical compounds in the complex mixture, because at a certain dilution the absorption spectrum of the molecule could appear, specifically, with its total spectral form or at least at one of these wavelengths. In this article, we will study the possibility of rapidly measuring catechin from strawberry extract by spectrophotometry in UV-VIS, while reformulating the Beer-Lambert law in a new form where the extinction coefficient did not depend not only of the chemical nature of the solute and the solvent but also of the excitation wavelength (ε(λ), Eq. (9)). A catechin-methanol solution is taken as a reference to study the spectral variation due to the various dilutions of the solution and the determination of a limiting concentration where the excitation wavelength becomes constant (203 nm), thus the extinction coefficient of the catechin, denoted ε₀, but the measurement sensitivity is suddenly reduced. A semi-empirical relationship is determined by linearization of the absorbance function which depended on the concentration (C) and the excitation wavelength (ε(λ)). A separation process will be exposed to recover the strawberry extract, as well as its spectral analysis. Finally, a procedure for analyzing any strawberry extract will be presented at the end of this scientific article.