Chemical Reference Methods, National Measurement Institute, NSW, Australia.
Drug Test Anal. 2012 Dec;4(12):928-33. doi: 10.1002/dta.1366. Epub 2012 Apr 29.
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.
澳大利亚国家计量研究院（NMIA）已经开发出一种精确的方法，用于测量人尿液中类固醇的碳同位素比值，以对一种冻干人尿液参考物质（CRM NMIA MX005）进行认证。该方法通过水解、溶剂提取和高效液相色谱（HPLC）纯化后，采用气相色谱-燃烧-同位素比质谱（GC-C-IRMS）分析来测量δ(13)C 值。已确定睾酮代谢物表雄酮、雄酮和内源性参考化合物（ERCs）11β-羟基雄酮和孕烷二醇的参考δ(13)C 值，以及睾酮、表睾酮、11-氧表雄酮和一系列差异（Δ(13)C）的信息值，这些差异是在睾酮代谢物和 ERCs 之间。测量不确定度通过扩展不确定度进行了严格评估，在 95%的覆盖水平下，参考δ(13)C 值的扩展不确定度在 1.1 到 1.6 ‰之间。
