title: An improved NMR method for the quantification of alpha-acids in hops and hop products.
abstract: A new and independent method for the quantification of alpha-acids in hops and hop products has been developed. NMR was used as a qualitative method for the complete assignment of all 1H- and 13C-NMR signals of the three main alpha-acids, cohumulone (1), humulone (2) and adhumulone (3). In a 13C two-dimensional INADEQUATE experiment, the 13C-NMR spectrum of 1 was unambiguously assigned via the carbon-carbon connectivities. Use of NMR as a quantitative method allowed quantification of the pure and individual alpha-acids 1 and 2, and the determination of the absolute concentration of solutions of these compounds. Quantification of alpha-acids by NMR is less complicated and more reliable than the methods used until now.
authors.affiliation: Department of Pharmacognosy, Leiden/Amsterdam Center for Drug Research, Gorlaeus Laboratories, PO Box 9502, 2300 RA Leiden, The Netherlands. a.hoek@chem.leidenuniv.nl
authors.forename: A C
authors.initials: AC
authors.lastname: Hoek
authors.forename: A C
authors.initials: AC
authors.lastname: Hermans-Lokkerbol
authors.forename: R
authors.initials: R
authors.lastname: Verpoorte
mesh_terms: D003512:Cyclohexanones / Q000032:analysis* / Q000737:chemistry; D053138:Cyclohexenes; D027582:Humulus / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015203:Reproducibility of Results; D013729:Terpenes / Q000032:analysis* / Q000737:chemistry
chemical_list: D003512:Cyclohexanones; D053138:Cyclohexenes; D013729:Terpenes; C442487:cohumulone; C442488:adhumulone; C007966:humulon