Simultaneous Structural Identification of Constituents in Active Herbal Extract of Gossypium Herbaceam Using Nuclear Magnetic Resonance/Liquid Chromatography-Mass Spectrometry Hetero-Correlation Spectroscopy

To simplify and accelerate the analytical routes for structure identification of constituents in complex mixture,based on an incomplete separation strategy,MS/NMR hetero-correlation spectroscopy(MS/NMR-HCS) was developed as a new analytical method to discover the intrinsic correlation between LC-MS and NMR data of the same constituent from mixture spectra.The ethanol crude extract of the petals of Gossypium herbaceam was separated into a series of fractions with the concentration of constituent dynamic variation by flash column chromatography.NMR/LC-MS HCS method was applied to identify the flavonol glycosides in these fractions.The complementary spectral information of the same individual constituent in the crude extract was simultaneously obtained from the spectra of mixtures,including retention time(Rt),mass/charge(m/z) and chemical shift(δ).And combined the LC-MS/MS and 2D NMR analysis,twelve constituents including two groups of co-eluted isomers were identified successfully.The results demonstrated that NMR/LC-MS HCS combined with the incompleted separation strategy could achieve the similar function of on-line LC-MS-NMR in an off-line mode by such a mathematics hyphenated approach.The new analytical strategy has the potential advantages for simplifying and accelerating the analytical routes for structure identification of constituents in complex mixture.Especially,this method is suitable for analysis and identification of minimum-quantity constituents and constituents with similar polarity which are hardly obtained in routine experimental conditions.