Intensified extraction of ionized natural products by ion pair centrifugal partition extraction

The potential of centrifugal partition extraction (CPE) combined with the ion-pair (IP) extraction mode to simultaneously extract and purify natural ionized saponins from licorice is presented in this work. The design of the instrument, a new laboratory-scale Fast Centrifugal Partition Extractor (FCPE300 (R)), has evolved from centrifugal partition chromatography (CPC) columns, but with less cells of larger volume. Some hydrodynamic characteristics of the FCPE300 (R) were highlighted by investigating the retention of the stationary phase under different flow rate conditions and for different biphasic solvent systems. A method based on the ion-pair extraction mode was developed to extract glycyrrhizin (GL), a biologically active ionic saponin naturally present in licorice (Glycyrrhiza glabra L., Fabaceae) roots. The extraction of GL was performed at a flow rate of 20 mL/min in the descending mode by using the biphasic solvent system ethyl acetate/n-butanol/water in the proportions 3/2/5 (v/v/v). Trioctylmethylammonium with chloride as a counter-ion (Al336 (R)) was used as the anion extractant in the organic stationary phase and iodide, with potassium as counter-ion, was used as the displacer in the aqueous mobile phase. From 20g of a crude extract of licorice roots, 2.2 g of GL were recovered after 70 min, for a total process duration of 90 min. The combination of the centrifugal partition extractor with the ion-pair extraction mode (IP-CPE) offers promising perspectives for industrial applications in the field of natural product isolation or for the fractionation of natural complex mixtures. (C) 2011 Elsevier B.V. All rights reserved.