title: Analysis of hop acids and their oxidized derivatives and iso-alpha-acids in beer by capillary electrophoresis-electrospray ionization mass spectrometry.
abstract: This study investigates the applicability of on-line coupling of capillary electrophoresis with electrospray ionization tandem mass spectrometry (CZE-ESI-MS) for the separation and characterization of alpha- and beta-acids and oxidized hop acids from crude extracts of different hop varieties. CZE-ESI-MS with negative-ion electrospray ionization proved to be a suitable technique for the determination of these types of natural compounds and their oxidized derivatives. The CZE parameters (pH, concentration, and buffer type) and ESI-MS parameters (nature and flow rate of the sheath liquid, nebulizer pressure, drying gas flow rate, temperature, and compound stability) were optimized. The optimized method provides the potential for a fast qualitative determination of hop acids and their oxidation compounds. The method was also applied to the determination of iso-alpha-acids in beer.
authors.affiliation: Department of Analytical Chemistry, Faculty of Sciences, University of Granada, c/ Fuentenueva s/n, 18071 Granada, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: García-Villalba
authors.forename: Sonia
authors.initials: S
authors.lastname: Cortacero-Ramírez
authors.forename: Antonio
authors.initials: A
authors.lastname: Segura-Carretero
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Martín-Lagos Contreras
authors.forename: Alberto
authors.initials: A
authors.lastname: Fernández-Gutiérrez
mesh_terms: D001515:Beer / Q000032:analysis*; D053138:Cyclohexenes; D019075:Electrophoresis, Capillary; D027582:Humulus / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D021241:Spectrometry, Mass, Electrospray Ionization; D013729:Terpenes / Q000032:analysis*
chemical_list: D053138:Cyclohexenes; D013729:Terpenes; C007966:humulon