Isolation and purification of glycyrrhizic acid with solvent extraction

Solvent extraction of glycyrrhizic acid (GA) from liquorice leaching solution was studied with tributyl phosphate, trialkylphosphine oxide, n-hexanol and 2-ethyl-hexanol as extractants. The results showed that GA was easily extracted into the organic phase in molecular state by the formation of hydrogen bond. pH was the key factor influencing the selectivity during extraction and stripping. The extraction mechanism was studied with transmitting electron microscopy and analysis of solute distribution. It was deduced that glycyrrhizic acid was extracted into the organic solvent in the form of molecular aggregation rather than as single molecules. (C) 2004 Elsevier B.V. All rights reserved.