Separation of phenolic compounds by centrifugal partition chromatography†
Phenolic compounds are ubiquitous biomolecules exhibiting a wide range of physiological properties, with application in the pharmaceutical and nutraceutical fields. In this work, aqueous biphasic systems (ABS) formed by polyethylene glycol and sodium polyacrylate, and inorganic salts or ionic liquids as electrolytes, were applied for the purification of caffeic, ferulic and protocatechuic acids (CA, FA, and PA, respectively), vanillin (VN) and syringaldehyde (SA), followed by the use of centrifugal partition chromatography (CPC) to reinforce the fractionation process scale-up. In single-step experiments in ABS, high selectivities and adequate partition coefficients (KCA = 2.78 ± 0.20; KPA = 0.44 ± 0.04; KFA = 0.23 ± 0.01; KVN = 1.12 ± 0.05 and KSA = 1.23 ± 0.02) were achieved using ABS formed by sodium chloride as the electrolyte. This system was further applied in CPC, allowing an efficient separation of the five phenolic compounds after the optimization of the equipment operational conditions, while demonstrating the potential of polymer-based ABS to be used in liquid–liquid chromatography. Finally, the recovery of the phenolic compounds (between 65 and 87%) with high purity from the ABS phases was demonstrated, allowing the reuse of the ABS phase-forming components, which was proved to be of low environmental impact. In fact, in a scenario where the polymeric phases are reused, the carbon footprint is decreased to 36%, as the consumption of new chemicals and water reduces considerably.