Two-dimensional LC–MS analysis of components in Swertia franchetiana Smith
An off-line 2-D-LC approach was developed for the separation and identification of components in extracts of Swertia franchetiana Smith, which is a traditional Chinese medicine. An octadecylsilica column was used for further separation of fractions from a cyano column with UV and MS detection. In this method, a longer column was used in the second dimension to improve the separation ability, and “on-column focusing” was adopted to reduce sample loss and pollution on concentrating the fractions from the first dimension. More than 118 and 575 components were detected in the chloroform and n-butanol extracts by this method, respectively. In contrast, only 20 and 95 peaks were detected by the one-dimensional method. Most of the additionally detected compounds were of low-abundance components. Many compounds can be preliminarily identified according to their UV and mass spectra in the two-dimensional method. The obtained results not only demonstrated the powerful resolution of 2-D-LC, but also led to in-depth comprehension of the UV and mass spectra of complex samples.