A simple way to configure on-line two-dimensional liquid chromatography for complex sample analysis: Acquisition of four-dimensional data

An on-line comprehensive two-dimensional liquid chromatography (HPLC x UPLC-TOF MS) was set up just using the injection valve of the ultra performance liquid chromatography (UPLC) as the interface through which the effluent of high performance liquid chromatography (HPLC) was injected automatically to UPLC coupled to time-of-flight mass spectrometry (TOF MS). As a demonstrative application, a complex sample of Traditional Chinese Medicine, Qingkailing was analyzed. As a result, a four-dimensional (4D) data containing 2D retention times, peak intensity and m/z ratios was plotted, where 398 peaks were counted and low concentration Components were distinguished from the high concentration ones with a total peak capacity of 1090. Comparing with traditional 3D data acquired by HPLC x HPLC, the 4D data generated by HPLC x UPLC-TOF MS can increase the number of recognized components by three times, reduce the analysis time by 75%. Such a configuration of HPLC x UPLC-TOF MS can realize easily upon commercial chromatographs while exhibited enhanced separation efficiency, high sensitivity, huge peak capacity and great potential in complex sample analysis. (C) 2012 Elsevier B.V. All rights reserved.