Luminescent Determination of Phytostilbene Resveratrol

The potential of lanthanide ions for the luminescent determination of resveratrol, a phytoalexin of polyphenolic structure, was investigated. Resveratrol occurs in significant amounts in grapes and can serve as a marker of quality and authenticity of grape wines and juices, making its reliable detection highly relevant for assessing the biological value and authenticity of winemaking products. The main spectral characteristics of resveratrol were determined. In the ultraviolet region, resveratrol solutions exhibit a broad absorption band with a high molar extinction coefficient, enabling efficient light absorption. The strongest luminescent response was observed upon complexation with Sc(III) ions, with a marked increase in luminescence intensity when the complex was immobilized on a Silicagel Merk L100/160 solid matrix compared to solution. Optimal complexation conditions were established: sorption from aqueous solution at pH 6.4–6.7 and Sc(III) concentration of 5·10-³ mol/L. The luminescence intensity of the Sc(III)-resveratrol complex was shown to depend on the metal concentration. The influence of surface-active and donor-active substances was also studied, with nonionic surfactants, particularly Brij-35, significantly enhancing the analytical signal. Based on these findings, a solid-phase luminescent method for the determination of resveratrol in wines and juices was developed using the Sc(III)-resveratrol-Brij-35 sorbate. The method demonstrated good reproducibility, with relative standard deviations ranging from 2.1% to 8.5% at n = 5 and P=0.95, confirming its suitability for quality control of grape-based products.