title: Determination of urinary 18 beta-glycyrrhetinic acid by gas chromatography and its clinical application in man.
abstract: A sensitive and quantitative gas chromatographic assay for the determination of 18 beta-glycyrrhetinic acid (18 beta-GA), the main metabolite of glycyrrhizin after oral licorice consumption in human urine, has been developed and validated. For the extraction of 18 beta-GA from urine two Sep-Pak C18 extractions, hydrolysis with Helix pomatia and three liquid-liquid extractions were performed, using 18 alpha-glycyrrhetinic acid (18 alpha-GA) as internal standard. Both 18 beta-GA and internal standard were converted into their pentafluorobenzyl-ester/trimethylsilyl-ether derivatives and detected by flame ionization detection using a WCOT-fused-silica capillary column. Good quality control data were obtained in precision and accuracy tests. The detection limit of the gas chromatographic method was 10 micrograms/l with a urine volume of 10 ml. A detection limit of 3 micrograms/l was obtained by performing GC-MS. The GC method was used to monitor the urinary excretion of 18 beta-GA after licorice consumption by two healthy volunteers and a patient suspected of licorice abuse. Furthermore, it was shown that this GC assay enables to detect other metabolites related to licorice consumption.
authors.affiliation: Department of Clinical Chemistry, University Hospital Groningen, The Netherlands.
authors.forename: C P
authors.initials: CP
authors.lastname: Guillaume
authors.forename: J C
authors.initials: JC
authors.lastname: van der Molen
authors.forename: M N
authors.initials: MN
authors.lastname: Kerstens
authors.forename: R P
authors.initials: RP
authors.lastname: Dullaart
authors.forename: B G
authors.initials: BG
authors.lastname: Wolthers
mesh_terms: D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006034:Glycyrrhetinic Acid / Q000652:urine*; D006035:Glycyrrhiza; D006372:Helix, Snails; D006801:Humans; D010946:Plants, Medicinal; D012015:Reference Standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D006034:Glycyrrhetinic Acid