title: Simultaneous molecular formula determinations of natural compounds in a plant extract using 15 T Fourier transform ion cyclotron resonance mass spectrometry.
abstract: BACKGROUND
  Plant extracts are a reservoir of pharmacologically active substances; however, conventional analytical methods can analyze only a small portion of an extract. Here, we report a high-throughput analytical method capable of determining most phytochemicals in a plant extract and of providing their molecular formulae from a single experiment using ultra-high-resolution electrospray ionization mass spectrometry (UHR ESI MS). UHR mass profiling was used to analyze natural compounds in a 70% ethanol ginseng extract, which was directly infused into a 15 T Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer for less than 10 min without a separation process.
  
  
  RESULTS
  The UHR FT-ICR MS yielded a mass accuracy of 0.5 ppm and a mass resolving power (m/Δm) of 1,000,000-270,000 for the range m/z 290-1,100. The mass resolution was sufficient to resolve the isotopic fine structure (IFS) of many compounds in the extract. After noise removal from 1,552 peaks, 405 compounds were detected. The molecular formulae of 123 compounds, including 33 ginsenosides, were determined using the observed IFS, exact monoisotopic mass, and exact mass difference. Liquid chromatography (LC)/FT-ICR MS of the extract was performed to compare the high-throughput performance of UHR ESI FT-ICR MS. The LC/FT-ICR MS detected only 129 compounds, including 19 ginsenosides. The result showed that UHR ESI FT-ICR MS identified three times more compounds than LC/FT-ICR MS and in a relatively shorter time. The molecular formula determination by UHR FT-ICR MS was validated by LC and tandem MS analyses of three known ginsenosides.
  
  
  CONCLUSIONS
  UHR mass profiling of a plant extract by 15 T FT-ICR MS showed that multiple compounds were simultaneously detected and their molecular formulae were decisively determined by a single experiment with ultra-high mass resolution and mass accuracy. Simultaneous molecular determination of multiple natural products by UHR ESI FT-ICR MS would be a powerful method to profile a wide range of natural compounds.
authors.affiliation: Division of Mass Spectrometry Research, Korea Basic Science Institute, Ochang, Chungcheongbuk-Do 363-883, South Korea.
authors.forename: Kyu Hwan
authors.initials: KH
authors.lastname: Park
authors.affiliation: Division of Mass Spectrometry Research, Korea Basic Science Institute, Ochang, Chungcheongbuk-Do 363-883, South Korea.
authors.forename: Min Sun
authors.initials: MS
authors.lastname: Kim
authors.affiliation: Division of Mass Spectrometry Research, Korea Basic Science Institute, Ochang, Chungcheongbuk-Do 363-883, South Korea.
authors.forename: Sun Jong
authors.initials: SJ
authors.lastname: Baek
authors.affiliation: Division of Mass Spectrometry Research, Korea Basic Science Institute, Ochang, Chungcheongbuk-Do 363-883, South Korea ; College of Pharmacy, Chungbuk National University, Cheongju 361-763, South Korea.
authors.forename: Ik Hyun
authors.initials: IH
authors.lastname: Bae
authors.affiliation: Bio Center, Chungbuk Techno Park, Ochang, Chungcheongbuk-Do 363-883, South Korea.
authors.forename: Sang-Wan
authors.initials: SW
authors.lastname: Seo
authors.affiliation: Bio Center, Chungbuk Techno Park, Ochang, Chungcheongbuk-Do 363-883, South Korea.
authors.forename: Jongjin
authors.initials: J
authors.lastname: Kim
authors.affiliation: Bio Center, Chungbuk Techno Park, Ochang, Chungcheongbuk-Do 363-883, South Korea.
authors.forename: Yong Kook
authors.initials: YK
authors.lastname: Shin
authors.affiliation: College of Pharmacy, Chungbuk National University, Cheongju 361-763, South Korea.
authors.forename: Yong-Moon
authors.initials: YM
authors.lastname: Lee
authors.affiliation: Division of Mass Spectrometry Research, Korea Basic Science Institute, Ochang, Chungcheongbuk-Do 363-883, South Korea.
authors.forename: Hyun Sik
authors.initials: HS
authors.lastname: Kim
keywords: FT-ICR MS; Ginsenosides; Isotopic fine structure; Molecular formula determination; Panax ginseng; Ultra-high resolution