Development and optimization of a method for the separation of platycosides in Platycodi Radix by comprehensive two-dimensional liquid chromatography with mass spectrometric detection

Abstract

Comprehensive two-dimensional chromatography (LC x LC) using combinations of two columns (C-18 x CN and C-18 x NH2) was employed with electrospray (ESI) mass spectrometry to analyze platycosides from root extract. Based on the capability of the C-18, CN and NH2 columns to separate the platycosides, the orthogonality in two-dimensional space according to each combination of columns was predicted from the correlation coefficients between the retention times of the 17 compounds separated by the independent CN and C-18 columns, and NH2 and C-18 columns. The expected distribution of the peaks was also compared with the two-dimensional plots obtained by practical separation in an LC x LC system. The increased peak capacities using C-18 x NH2 allowed three minor components and five isomers of the platycosides to be newly separated, which were not identified with 1D-LC using the individual C-18 column, whereas the combination of C-18 x CN did not result in any improvement of the separation performance. (c) 2010 Elsevier B.V. All rights reserved.