Adsorbents, mobile phases, and strategies for the chromatographic separation of betulinic, oleanolic, and ursolic acids

Abstract

A critical overview of the separation of three relevant triterpenic acids, namely betulinic, oleanolic, and ursolic acids, by liquid and supercritical fluid chromatography is presented in this review. These triterpenic acids are commonly found in different biomass residues and have raised great research attention in recent years due to their broad and valuable therapeutic properties. Accordingly, fundamental aspects such as solubilities in single and mixed solvents, commercial stationary phases (octadecylsilyl and other bonded phases like triacontylsilyl, as well as porous graphitic columns), custom adsorbents (molecularly imprinted polymers and other polymeric adsorbents), mobile phases (conventional HPLC solvents and super/subcritical fluids), mobile-phase modifiers (acidic, basic, and cyclodextrins), pre-column derivatization strategies, and influence of temperature have been compiled, analyzed and thoroughly discussed in terms of (calculated) separation selectivities, peaks resolution, orders of elution, systems descriptors, etc. The most relevant achievements and gaps in this area of research are highlighted, together with a final comparison of the separation performance of the chromatographic systems reported in the literature.