Direct characterization of bitter acids in a crude hop extract by liquid chromatography-atmospheric pressure chemical ionization mass spectrometry

  • Xiaozhe Zhang
  • Xinmiao LiangEmail author
  • Hongbin Xiao
  • Qing Xu


The applicability of on-line coupling of reversed-phase high-performance liquid chromatography to atmospheric pressure ionization tandem mass spectrometry for the separation and characterization of hop acids mixture from the crude extract of Humulus lupulus was investigated. The solvent system consisting of acetonitrile-aqueous formic acid was used to give proper separation of the six main hop bitter acids within 30 min. Further structural information about the components was acquired by collision-induced dissociation (CID). On the basis of analyses of the fragmentation patterns of the major α- and β-bitter acids respectively, identification of the minor ones was performed using selected reaction monitoring (SRM) with a group of qualitatively relevant selected precursor-product ion transitions for each bitter acid in a single high performance liquid chromatography (HPLC) run. Using this technique, six minor hop acids, including “adprelupulone” observed for the first time in natural resources, were detected along with the six major acids. This hyphenated techniques provides potency for rapid qualitative determination of analogs and homologs in mixtures.


High Performance Liquid Chromatography Select Reaction Monitor Bitter Acid Pressure Chemical Ionization Mass Spectrometry Centrifugal Partition Chromatography 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. 1.
    Smith, R. J.; Davidson, D. Natural Foam Stabilizing and Bittering Compounds Derived from Hops. J. Am. Soc. Brew. Chem. 1998, 56, 52–57.Google Scholar
  2. 2.
    Hermans-Lokkerbol, A. C. J.; Hoek, A. C.; Verpoorte, R. Preparative Separation of Bitter Acids from Hop Extracts by Centrifugal Partition Chromatography. J. Chromatogr. A 1997, 771, 71–80.CrossRefGoogle Scholar
  3. 3.
    Fung, S. Y.; Brussee, J.; van der Hoeven, R. A. M.; Niessen, W. M. A.; Scheffer, J. J. C.; Verpoorte, R. Analysis of Proposed Aromatic Precursors of Hop Bitter Acids. J. Nat. Prod. 1994, 57, 452–459.CrossRefGoogle Scholar
  4. 4.
    Hermans-Lokkerbol, A. C. J.; Verpoorte, R. Development and Validation of a High Performance Liquid Chromatography System for the Analysis of Hop Bitter Acids. J. Chromatogr. A 1994, 669, 65–73.CrossRefGoogle Scholar
  5. 5.
    Hermans-Lokkerbol, A. C. J.; Verpoorte, R. Preparative Separation and Isolation of Three α-Bitter Acids from Hop, Humulus lupulus L., by Centrifugal Partition Chromatography. J. Chromatogr. A 1994, 664, 45–53.CrossRefGoogle Scholar
  6. 6.
    Hann, J. T. Fast LC Analysis of the α-Acid Content of “Fresh” and “Aged” Hops. Chromatographia 1987, 24, 510–512.CrossRefGoogle Scholar
  7. 7.
    Sandra, P.; Steenbeke, G.; Ghys, M. Micro Liquid Chromatography-Diode Array Detection of Hop Bitter Acids. J. High Res. Chromatogr. 1990, 13, 527–528.CrossRefGoogle Scholar
  8. 8.
    Verzele, M.; van de Velde, N. High Performance Liquid Chromatography with Photodiode Array Detection of Minor Hop Bitter Acids in Hops Extracts and in Beer. J. Chromatogr. 1987, 387, 473–480.CrossRefGoogle Scholar
  9. 9.
    Vindevogel, J.; Sandra, P. Micellar Eelectrokinetic Chromatography of Ionic Compounds: The Analysis of Hop Bitter Acids. J. High Res. Chromatogr. 1991, 14, 795–801.CrossRefGoogle Scholar
  10. 10.
    Hofte, A. J. P.; van der Hoeven, R. A. M. Characterization of Hop Acids by Liquid Chromatography with Negative Electrospray Ionization Mass Spectrometry. J. Am. Soc. Brew. Chem. 1998, 56, 118–122.Google Scholar

Copyright information

© American Society for Mass Spectrometry 2004

Authors and Affiliations

  • Xiaozhe Zhang
    • 1
  • Xinmiao Liang
    • 1
    Email author
  • Hongbin Xiao
    • 1
  • Qing Xu
    • 1
  1. 1.Group of Pharmaceutical Chemistry, Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalianChina

Personalised recommendations