Chemoinformatics based comprehensive two-dimensional liquid chromatography-quadrupole time-of-flight mass spectrometry approach to chemically distinguish Chrysanthemum species

An effective comprehensive two-dimensional liquid chromatography (LC x LC) coupled with quadrupole timeof-flight mass spectrometry (Q-TOF/MS) method was developed for quantitative determination of 19 active constituents in chrysanthemum species. Separation was achieved on a LC x LC system, with Zorbax Eclipse Plus C18 column (2.1 x 100 mm, 3.5 mu m) used in the first dimension (1D), Poroshell 120 Bonus-RP column (3.0 x 50 mm, 2.7 mu m) in the second dimension (2D). An optimal flow rate of 0.1 mL/min in 1D combined with 2.0 mL/min in 2D was utilized to improve the resolution and peak shape of the analytes. A synchronized gradient elution program was optimized to make for the 2D chromatographic resolution and the final peak capacity. The established method was then applied for the contents determination of the 19 analytes in all the chrysanthemum samples collected. Based on the content data set of these components, principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and hierarchical cluster analysis (HCA) were performed to distinguish the chrysanthemum of different varieties. 29 selected chrysanthemum products were classified into five clusters, with Chuju, Jinzhanju, Taiju and Wanshouju distinguished from each other. However, Hangbaiju, Huangju, Gongju, and Xueju clustered into a group due to their similarities in the analytes content. This study shows that LC x LC/Q-TOF MS in combination with PCA, PLS-DA and HCA can be applied successfully as an effective method for the classification and quality control of chrysanthemum.