The use of gas chromatography-mass spectrometry/combustion/isotope ratio mass spectrometry to demonstrate progesterone treatment in bovines.

Currently, no analytical method is available to demonstrate progesterone administration in biological samples collected in rearing animals, and therefore, tracking the abuse of this popular growth promoter is arduous. In this study, a method is presented to reveal progesterone (PG) treatment on the basis of carbon isotope measurement of 5ß-pregnane-3α, 20α-diol (BAA-PD), a major PG metabolite excreted in bovine urine, by gas chromatography-mass spectrometry/combustion/isotope ratio mass spectrometry (GC-MS/C/IRMS). 5-Androstene-3ß,17α-diol (AEdiol) is used as endogenous reference compound. Intermediate precisions (n=11) of 0.56‰ and 0.68‰ have been determined for AEdiol and BAA-PD, respectively. The analytical method was used for the very first time to successfully differentiate urine samples collected in treated and untreated animals.

Simultaneous Detection of Androgen and Estrogen Abuse in Breeding Animals by Gas Chromatography-Mass Spectrometry/Combustion/Isotope Ratio Mass Spectrometry (GC-MS/C/IRMS) Evaluated against Alternative Methods.

The administration of synthetic homologues of naturally occurring steroids can be demonstrated by measuring (13)C/(12)C isotopic ratios of their urinary metabolites. Gas chromatography-mass spectrometry/combustion/isotope ratio mass spectrometry (GC-MS/C/IRMS) was used in this study to appraise in a global approach isotopic deviations of two 17ß-testosterone metabolites (17α-testosterone and etiocholanolone) and one 17ß-estradiol metabolite (17α-estradiol) together with those of 5-androstene-3ß,17α-diol as endogenous reference compound (ERC). Intermediate precisions of 0.35‰, 1.05‰, 0.35‰, and 0.21‰, respectively, were observed (n = 8). To assess the performance of the analytical method, a bull and a heifer were treated with 17ß-testosterone propionate and 17ß-estradiol-3-benzoate. The sensitivity of the method permitted the demonstration of 17ß-estradiol treatment up to 24 days. For 17ß-testosterone treatment, the detection windows were 3 days and 24 days for the bull and the heifer, respectively. The capability of GC-MS/C/IRMS to demonstrate natural steroid abuse for urinary steroids was eventually compared to those of mass spectrometry (LC-MS/MS) when measuring intact steroid esters in blood and hair.

Application of gas chromatography-mass spectrometry/combustion/isotope ratio mass spectrometry (GC-MS/C/IRMS) to detect the abuse of 17ß-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 17ß-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-3ß,17α-diol, in bovine urine. The intermediate precisions were determined as 0.46 and 0.26‰ for 5-androstene-3ß,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.

Elimination kinetics of dexamethasone in bovine urine, hair and feces following single administration of dexamethasone acetate and phosphate esters.

Corticosteroids are hormonal substances widely used in human and veterinary medicine for their anti-inflammatory properties. Among the numerous existing artificial corticosteroids, dexamethasone remains the most commonly used, mainly throughout esterified forms such as acetate or phosphate. An experimental study was designed to assess its drug residue levels in urine and feces, as well as its fixation in bovine hair following a single administration of 0.15 mg/kg b.w. dexamethasone acetate and 0.12 mg/kg b.w. dexamethasone sodium phosphate. Different analytical methods based on GC-MS or LC-MS/MS were used for measuring dexamethasone and its esterified forms, which were implemented in 3 different European laboratories in the field that collaborated for this study. The obtained results confirmed the high and rapid urinary excretion rate of dexamethasone, with a maximal concentration (267 µg/L) measured one day after administration and 98% elimination within 3 days. The concentrations obtained with the GC-NCI-MS procedure (using chemical oxidation as derivatization) were found significantly higher than the ones obtained with LC-ESI-MS/MS, indicating a possible contribution of dexamethasone phase I and/or II metabolites to the monitored signal. Fecal elimination was also found rapid (95% elimination within 3 days) with a maximum concentration level (28.5 µg/kg) observed one day after administration. Detectable levels of dexamethasone in hair appeared on day 2 (11.5 µg/kg), reached a maximum around one week, and could be identified until 22 days upon treatment, establishing the suitability of hair as a biological matrix for medium to long-term residue controls of dexamethasone.