Application of Gas Chromatography–Mass Spectrometry/Combustion/Isotope Ratio Mass Spectrometry (GC-MS/C/IRMS) To Detect the Abuse of 17β-Estradiol in Cattle

Although the ability to differentiate between endogenous steroids and synthetic homologues on the basis of their 13C/12C isotopic ratio has been known for over a decade, this technique has been scarcely implemented for food safety purposes. In this study, a method was developed using gas chromatography–mass spectrometry/combustion/isotope ratio mass spectrometry (GC-MS/C/IRMS) to demonstrate the abuse of 17β-estradiol in cattle, by comparison of the 13C/12C ratios of the main metabolite 17α-estradiol and an endogenous reference compound (ERC), 5-androstene-3β,17α-diol, in bovine urine. The intermediate precisions were determined as 0.46 and 0.26‰ for 5-androstene-3β,17α-diol and 17α-estradiol, respectively. This is, to the authors’ knowledge, the first reported use of GC-MS/C/IRMS for the analysis of steroid compounds for food safety issues.