title: Certification of steroid carbon isotope ratios in a freeze-dried human urine reference material.
abstract: An accurate method for the measurement of carbon isotope ratios of steroids in human urine has been developed at the National Measurement Institute, Australia (NMIA) for the certification of a freeze-dried human urine reference material (CRM NMIA MX005). The method measures δ(13)C values by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) analysis following hydrolysis, solvent extraction and high performance liquid chromatography (HPLC) purification. Reference δ(13)C values for testosterone metabolites etiocholanolone, androsterone, and endogenous reference compounds (ERCs) 11β-hydroxyandrosterone and pregnanediol were determined, as well as information δ(13)C values for testosterone, epitestosterone, 11-oxoetiocholanolone, and a range of differences (Δ(13)C) between testosterone metabolites and ERCs. The measurement uncertainty was rigorously evaluated with expanded uncertainties for the reference δ(13)C values between 1.1 and 1.6 ‰ at the 95% coverage level.
authors.affiliation: Chemical Reference Methods, National Measurement Institute, NSW, Australia. ellaine.munton@measurement.gov.au
authors.forename: Ellaine
authors.initials: E
authors.lastname: Munton
authors.forename: Fong-Ha
authors.initials: FH
authors.lastname: Liu
authors.forename: E
authors.initials: E
authors.lastname: John Murby
authors.forename: D
authors.initials: D
authors.lastname: Brynn Hibbert
mesh_terms: D045930:Anabolic Agents / Q000652:urine*; D000738:Androsterone / Q000031:analogs & derivatives / Q000652:urine; D001315:Australia; D015415:Biomarkers / Q000652:urine; D001711:Biotransformation; D002138:Calibration; D002247:Carbon Isotopes / Q000652:urine*; D002568:Certification / Q000592:standards*; D002851:Chromatography, High Pressure Liquid; D004300:Doping in Sports; D005043:Etiocholanolone / Q000652:urine; D005612:Freeze Drying / Q000592:standards*; D008401:Gas Chromatography-Mass Spectrometry / Q000592:standards*; D006801:Humans; D006868:Hydrolysis; D058573:Performance-Enhancing Substances / Q000652:urine*; D011237:Predictive Value of Tests; D011276:Pregnanediol / Q000652:urine; D011786:Quality Control; D012015:Reference Standards; D015203:Reproducibility of Results; D012997:Solvents / Q000737:chemistry; D015813:Substance Abuse Detection / Q000379:methods / Q000592:standards*; D013739:Testosterone / Q000652:urine*; D035501:Uncertainty
chemical_list: D045930:Anabolic Agents; D015415:Biomarkers; D002247:Carbon Isotopes; D058573:Performance-Enhancing Substances; D012997:Solvents; D013739:Testosterone; C002528:11 beta-hydroxyandrosterone; D005043:Etiocholanolone; D000738:Androsterone; D011276:Pregnanediol