Natural phenolic compounds have elicited extensive interest in the last decades as a result of the beneficial physiological properties of these molecules and their importance in the human diet. The extreme diversity of natural phenolics has however highlighted the requirement of improved methods for phenolic analysis. In this talk, an overview of the application of comprehensive 2-dimensional hydrophilic interaction chromatography x reversed phase liquid chromatography (HILICxRP-LC) as means of providing high-resolution separation of complex phenolic fractions will be presented.

An introduction to the fundamental aspects relevant to the optimisation of LCxLC separations will be presented, together with the criteria used to evaluate practical performance gains compared to 1-dimensional HPLC. The application of these principles in the development of a systematic optimisation procedure for HILICxRP-LC separation in off-line, on-line and stop-flow modes will be demonstrated, highlighting the practical aspects relevant in the coupling of these separation modes. The performance of each of these approaches will be compared on the hand of experimental data. Finally, real-life examples of the application of off-line and on-line HILICxRP-LC separation in combination with UV, fluorescence and ESI-MS detection for the analysis of diverse a range of phenolic compounds, including proanthocyanidins, flavonols, chalcones, phenolic acids and anthocyanins will be presented. The gain in performance provided by HILICxRP-LC separation will be discussed based on experimental data for cocoa, grapes, rooibos and green teas, berries and several vegetables.