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 (13)C/(12)C 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 (13)C/(12)C 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.