title: Novel algorithm for simultaneous component detection and pseudo-molecular ion characterization in liquid chromatography-mass spectrometry.
abstract: Resolving components and determining their pseudo-molecular ions (PMIs) are crucial steps in identifying complex herbal mixtures by liquid chromatography-mass spectrometry. To tackle such labor-intensive steps, we present here a novel algorithm for simultaneous detection of components and their PMIs. Our method consists of three steps: (1) obtaining a simplified dataset containing only mono-isotopic masses by removal of background noise and isotopic cluster ions based on the isotopic distribution model derived from all the reported natural compounds in dictionary of natural products; (2) stepwise resolving and removing all features of the highest abundant component from current simplified dataset and calculating PMI of each component according to an adduct-ion model, in which all non-fragment ions in a mass spectrum are considered as PMI plus one or several neutral species; (3) visual classification of detected components by principal component analysis (PCA) to exclude possible non-natural compounds (such as pharmaceutical excipients). This algorithm has been successfully applied to a standard mixture and three herbal extract/preparations. It indicated that our algorithm could detect components' features as a whole and report their PMI with an accuracy of more than 98%. Furthermore, components originated from excipients/contaminants could be easily separated from those natural components in the bi-plots of PCA.
authors.affiliation: School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Xiaoan
authors.initials: X
authors.lastname: Wang
authors.affiliation: School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors.forename: Siukwan
authors.initials: S
authors.lastname: Wo
authors.affiliation: School of Chinese Medicine, Hong Kong Baptist University, 7 Baptist University Road, Kowloon Tong, Hong Kong, China.
authors.forename: Hingman
authors.initials: H
authors.lastname: Ho
authors.affiliation: School of Chinese Medicine, Hong Kong Baptist University, 7 Baptist University Road, Kowloon Tong, Hong Kong, China.
authors.forename: Quanbin
authors.initials: Q
authors.lastname: Han
authors.affiliation: College of Pharmaceutical Sciences, Zhejiang University, Hangzhou 310058, PR China.
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Fan
authors.affiliation: School of Pharmacy, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. Electronic address: joanzuo@cuhk.edu.hk.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Zuo
mesh_terms: D000465:Algorithms; D002853:Chromatography, Liquid / Q000379:methods*; D004365:Drugs, Chinese Herbal / Q000737:chemistry; D013058:Mass Spectrometry / Q000379:methods*; D008970:Molecular Weight; D025341:Principal Component Analysis; D013223:Statistics as Topic / Q000379:methods*; D013997:Time Factors
chemical_list: D004365:Drugs, Chinese Herbal
keywords: Component detection; Isotopic distribution; Mono-isotopic mass; Natural products; Pseudo-molecular ion