Isolation of the active constituents in natural materials by 'heart-cutting' isocratic reversed-phase two-dimensional liquid chromatography

A multidimensional heart-cutting reversed-phase HPLC separation approach, where two columns were operated independently via two six-port two-position switching valves, was employed in the isolation of a major bioactive found in the ethanol-water (80:20) crude extract of Clerodendrum floribundum. In this mode of operation, the specific productivity of the multidimensional approach under overload conditions was twice that of conventional gradient methods with the same loading factor. Isolated sample purities were greater than 99% with recoveries of 95%. The independent operation of each of the two columns employed in the multidimensional approach allowed the cycle time to be less than 7 min, compared to 23 min in the gradient elution single-dimension mode of operation. (C) 2004 Elsevier B.V. All rights reserved.