Selectivity of Separation of Natural Antioxidants in Gradient Reversed-Phase Liquid Chromatography.

Polyphenols are a large family of compounds widely distributed in plants and related food products. Many of them, including phenolic acids and flavonoids, are natural antioxidants, which have beneficial effects on human health. The polyphenols can be easily analyzed using liquid chromatography in reversed-phase mode; however, the optimization of separation selectivity is usually required especially for structurally similar or isomeric compounds. The aim of the thesis was to develop a systematic approach to the selection of columns and mobile phases suitable for separation of natural phenolic antioxidants, based on the correlations between the gradient retention times and molecular structure-descriptors of representative phenolic acid and flavonoid standards. For this aim, 14 compounds belong to the group of phenolic acids and flavonoids were chosen and were subjected to the study. Multiple linear regression, cluster analysis and window†"diagram optimization strategies were combined for data evaluation. The gradient retention data for a set of phenolic compounds obtained using six different columns packed with porous shell particles with non-polar chemically bonded stationary phases were used to establish the retention model. The retention factors were then applied for evaluation of selectivity using linear free energy relationship concept, which enables comparison of selectivity of separation among different stationary phases used.