The ultimate veal calf reference experiment: Hormone residue analysis data obtained by gas and liquid chromatography tandem mass spectrometry

Abuse of anabolic agents in beef cattle: Could bile be a possible alternative matrix?

European Union prohibited the use of anabolic agents in food producing animals since 1988. An efficient control of abuses is guaranteed not only by highly performing analytical methods, but also by knowledge of metabolic pathways, kinetics of elimination and tissue distribution. To obtain data concerning metabolites production and accumulation in bile, two typical growth promoting treatments are carried out in cattle. In the first study, sixteen beef cattle were implanted with trenbolone acetate and estradiol. In the second one, three animals were implanted with zeranol and three were fed a diet containing zearalenone. Methods based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) were developed and validated to quantify the analytes of interest. The results evidenced that the biliary concentrations of the marker residues were always higher than those determined at the same time in urine and liver which are the matrices generally collected within the official monitoring programmes.

Evaluation of the discriminative potential of a novel biomarker for estradiol treatments in bovine animals

The endogenous occurrence of natural hormones obstructs the application of classical targeted methods as confirmatory options. In the case of estradiol, the ultimate confirmation of its exogenous administration relies on gas chromatography coupled to combustion/isotope ratio mass spectrometry (GC-C/IRMS). A serum dipeptide composed of pyroglutamic acid and phenylalanine was identified as a potential biomarker of estradiol treatments in adult cows. To evaluate its potential to pinpoint suspicious samples, samples from prepubertal females under different estrogenic treatments have been analyzed. The results confirmed the up-regulation of the dipeptide in adult bovines. The 2-week-old females exhibited short-lasting responses only in a few animals. The 6-month-old female showed a delayed but clear increase on the biomarker level. The composition of the anabolic preparations, the dose, and/or the administration route are possible additional reasons for the reduced response in young animals. A comparison to previous results reported by various researchers is included.

Development and assessment of a novel Arxula adeninivorans androgen screen (A-YAS) assay and its application in analysis of cattle urine

The novel A-YAS assay for the detection of androgenic activity in liquid samples such as urine has been developed and assessed. The assay is based on transgenic Arxula adeninivorans yeast cells as the bio-component. The cells were engineered to co-express the human androgen receptor (hAR) gene and the inducible phytase reporter gene (phyK, derived from Klebsiella sp. ASR1), under the control of an Arxula derived glucoamylase (GAA) promoter, which had been modified by the insertion of hormone-responsive elements (HREs). The Arxula transformation/expression platform Xplor®2 was used to select stable mitotic resistance marker free transformants and the most suitable cells were characterized for performance as a sensor bio-component. The assay is easy-to-use, fast (6-25 h) and is currently the most sensitive yeast-based androgen screen with an EC50, limit of detection and of quantification values for 5α-dihydrotestosterone (DHT) of 277.1±53.0, 56.5±4.1 and 76.5±6.7 ng L(-1), respectively. Furthermore, the assay allows the determination of androgenic and anti-androgenic activity of various compounds such as naturally occurring androgens and estrogens, pharmaceuticals and biocides. The robustness of the A-YAS assay enables it to be used for analysis of complex samples such as urine. The results of the analysis of a number of cattle urine samples achieved by the A-YAS assay correlate well with GC-MS analysis of the same samples.

High-throughput bioaffinity mass spectrometry for screening and identification of designer anabolic steroids in dietary supplements

A generic high-throughput bioaffinity liquid chromatography-mass spectrometry (BioMS) approach was developed and applied for the screening and identification of known and unknown recombinant human sex hormone-binding globulin (rhSHBG)-binding designer steroids in dietary supplements. For screening, a semi-automated competitive inhibition binding assay was combined with fast ultrahigh-performance-LC-electrospray ionization-triple-quadrupole-MS (UPLC-QqQ-MS). 17β-Testosterone-D3 was used as the stable isotope label of which the binding to rhSHBG-coated paramagnetic microbeads was inhibited by any other binding (designer) steroid. The assay was performed in a 96-well plate and combined with the fast LC-MS, 96 measurements could be performed within 4 h. The concentration-dependent inhibition of the label by steroids in buffer and dietary supplements was demonstrated. Following an adjusted bioaffinity isolation procedure, suspect extracts were injected into a chip-UPLC(NanoTile)-Q-time-of-flight-MS system for full-scan accurate mass identification. Next to known steroids, 1-testosterone was identified in three of the supplements studied and the designer steroid tetrahydrogestrinone was identified in a spiked supplement. The generic steroid-binding assay can be used for high-throughput screening of androgens, estrogens, and gestagens in dietary supplements to fight doping. When combined with chip-UPLC-MS, it is a powerful tool for early warning of unknown emerging rhSHBG bioactive designer steroids in dietary supplements.

Endogenous steroid profiling by gas chromatography-tandem mass spectrometry and multivariate statistics for the detection of natural hormone abuse in cattle

For years it has been suspected that natural hormones are illegally used as growth promoters in cattle in the European Union. Unfortunately there is a lack of methods and criteria that can be used to detect the abuse of natural hormones and distinguish treated from non-treated animals. Pattern recognition of steroid profiles is a promising approach for tracing/detecting the abuse of natural hormones administered to cattle. Traditionally steroids are analysed in urine as free steroid after deconjugation of the glucuronide (and sulphate) conjugates. The disadvantage of this deconjugation is that valuable information about the steroid profile in the sample is lost. In this study we develop a method to analyse steroids at very low concentration levels (ng l(-1)) for the free steroid, glucuronide and sulphate conjugates in urine samples. This method was used to determine concentrations of natural (pro)hormones in a large population (n = 620) of samples from male and female bovine animals and from bovine animals treated with testosterone-cypionate, estradiol-benzoate, dihydroepiandrosterone and pregnenolone. The data acquired were used to build a statistical model applying the multivariate technique 'Soft Independent Modeling of Class Analogy' (SIMCA). It is demonstrated that by using this model the results of the urine analysis can indicate which animal may have had illegal treatment with natural (pro)hormones.

Improvement of estradiol esters monitoring in bovine hair by dansylation and liquid chromatography/tandem mass spectrometry analysis in multiple reaction monitoring and precursor ion scan modes

RATIONALE

The control of forbidden anabolic practices in cattle in the European Union has become challenging since endogenous compounds such as estradiol derivatives can potentially be used as growth promoters. Due to the great difficulty in establishing a reference threshold value for endogenous steroids, the direct detection of steroid esters in hair is an efficient strategy for the detection of 'natural' steroid abuse in cattle.

METHODS

The present study aimed to develop and validate according to the current European standards a specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) analytical strategy to monitor estrogen esters in bovine hair. The analysis was performed by positive ion electrospray ionisation (ESI+) after dansylation. Two acquisition modes were then assessed: single reaction monitoring and precursor ion scanning.

RESULTS

The results showed that the introduction of a dansylation step strongly improves the sensitivity of the detection of estradiol-17-esters by LC/(ESI+)-MS/MS. The CCα values are in the range 1-10 ng g(-1) after optimisation, except for estradiol decanoate for which the derivatisation is not efficient. In addition, this LC/MS/MS approach makes it possible to carry out a precursor ion scan to screen for the presence of these estradiol 17-esters in hair samples.

CONCLUSIONS

Based on the specific product ions, i.e. m/z 255 in native conditions or m/z 171 after dansylation, this strategy has the advantage of detecting any (un)known estradiol ester and of giving access to the [M + H](+) ion of the suspected ester through only a single analysis.

Gas chromatography coupled to mass spectrometry-based metabolomic to screen for anabolic practices in cattle: identification of 5α-androst-2-en-17-one as new biomarker of 4-androstenedione misuse

The use of anabolic steroids as growth promoters for meat-producing animals is banned within the European Union. However, screening for the illegal use of natural steroid hormones still represents a difficult challenge because of the high interindividual and physiological variability of the endogenous concentration levels in animals. In this context, the development of untargeted profiling approaches for identifying new relevant biomarkers of exposure and/or effect has been emerging for a couple of years. The present study deals with an untargeted metabolomics approach on the basis of GC-MS aiming to reveal potential biomarkers signing a fraudulent administration of 4-androstenedione (AED), an anabolic androgenic steroid chosen as template. After a sample preparation based on microextraction by packed sorbent, urinary profiles of the free and deglucurono-conjugates urinary metabolites were acquired by GC-MS in the full-scan acquisition mode. Data processing and chemometric procedures highlighted 125 ions, allowing discrimination between samples collected before and after an administration of 4-AED. After a first evaluation of the signal robustness using additional and independent non-compliant samples, 17 steroid-like metabolites were pointed out as relevant candidate biomarkers. All these metabolites were then monitored using a targeted GC-MS/MS method for an additional assessment of their capacity to be used as biomarkers. Finally, two steroids, namely 5α-androstane-3β,17α-diol and 5α-androst-2-en-17-one, were concluded to be compatible with such a definition and which could be finally usable for screening purpose of AED abuse in cattle.

Endogenous boldenone-formation in cattle: alternative invertebrate organisms to elucidate the enzymatic pathway and the potential role of edible fungi on cattle's feed

Although beta-boldenone (bBol) used to be a marker of illegal steroid administration in calves, its endogenous formation has recently been demonstrated in these vertebrates. However, research on the pathway leading to bBol remains scarce. This study shows the usefulness of in vivo invertebrate models as alternatives to vertebrate animal experiments, using Neomysis integer and Lucilia sericata. In accordance with vertebrates, androstenedione (AED) was the main metabolite of beta-testosterone (bT) produced by these invertebrates, and bBol was also frequently detected. Moreover, in vitro experiments using feed-borne fungi and microsomes were useful to perform the pathway from bT to bBol. Even the conversion of phytosterols into steroids was shown in vitro. Both in vivo and in vitro, the conversion of bT into bBol could be demonstrated in this study. Metabolism of phytosterols by feed-borne fungi may be of particular importance to explain the endogenous bBol-formation by cattle. To the best of our knowledge, it is the first time the latter pathway is described in literature.

Steroids excreted in urine by neonates with 21-hydroxylase deficiency: characterization, using GC-MS and GC-MS/MS, of the D-ring and side chain structure of pregnanes and pregnenes

Steroid metabolites in urine from neonates with 21-hydroxylase deficiency are predominantly polyhydroxylated 17-hydroxyprogesterone and androgen metabolites, and most have incompletely defined structure. This study forms part of a comprehensive project to characterize and identify these in order to enhance diagnosis and to further elucidate neonatal types of steroid metabolism. Steroids were analyzed, after extraction and enzymatic conjugate hydrolysis, as methyloxime-trimethylsilyl ether derivatives on gas-chromatographs coupled to quadrupole and ion-trap mass-spectrometers. GC-MS and GC-MS/MS spectra, obtained with constant excitation conditions, were used together to determine the structure of the D-ring and the side chain of 20-oxo and 20-hydroxy pregnane(ene)s without oxo groups on the A-, B-, and C-ring. All possible combinations of D-ring and side chain configuration were considered. Most fragmentations could be interpreted as partial or complete D-ring cleavages with loss of the side chain, aided by comparison with spectra of deuterated derivatives and of borohydride reduced metabolites. Possible rearrangement ions are also discussed. More than 140 endogenous metabolites were characterized. GC-MS/MS was especially beneficial for characterization of compounds with 16,17-dihydroxy-20-oxo structure, interpreted as markers of intra-uterine enzyme induction. It also assisted the differentiation of 16-hydroxy-20-oxo metabolites, present in urine of non-affected neonates, from the diagnostic 17-hydroxy-20-oxosteroids and enabled the detection of 15,17-dihydroxy-20-oxo compounds in low concentrations. The presence of 17,21-dihydroxylated pregnane(ene)s despite the deficit in CYP21A2 is discussed. We conclude that GC-MS combined with GC-MS/MS allows reliable identification of the structure of the D-ring and side chain of pregnane(ene)s without prior isolation, even when in low concentrations in urine.

Criteria to distinguish between natural situations and illegal use of boldenone, boldenone esters and boldione in cattle 2. Direct measurement of 17beta-boldenone sulpho-conjugate in calf urine by liquid chromatography--high resolution and tandem mass spectrometry

Boldenone is banned in the European Union (Directive 96/22/EC) as growth promoter for meat producing animals. Boldione (ADD), boldenone and boldenone esters (mainly the undecylenate form) are commercially available as anabolic preparations, either to the destination of human, horse or cattle. Since the late 90s, the natural occurrence of boldenone metabolites has been reported in cattle. According to EU regulation, the unambiguous demonstration of boldenone administration in bovine urine should be provided on the basis of boldenone identification in the corresponding conjugate fraction. An analytical method has been developed and validated according to current standards with main concern to the measurement of intact 17beta-boldenone-sulphate. The analytical procedure included direct extraction-purification of target analyte on octadecylsilyl cartridges and direct detection of phase II metabolite by liquid chromatography (negative electrospray), tandem mass spectrometry (QqQ) or high resolution mass spectrometry (Orbitrap). Decision limit (CCalpha) and detection capability (CCbeta) were respectively 0.2 microg L(-1) and 0.4 microg L(-1) on triple quadrupole and 0.1 microg L(-1) and 0.2 microg L(-1) on hybrid system. The method was successfully applied to the analysis of incurred samples collected in different experiments. 17beta-Boldenone-sulphate was measurable up to 36h after oral administration of boldione, and 30 days after 17beta-boldenone undecylenate intra-muscular injection. This conjugate form was never detected in non-treated animals, confirming its status of definitive candidate marker for boldenone administration in calf.

Boldenone, boldione, and milk replacers in the diet of veal calves: the effects of phytosterol content on the urinary excretion of boldenone metabolites

Twenty-six veal calves were split into two groups and fed two milk replacers with a different content of phytosterols for 26 days; then, 14 calves (7 animals from each diet) were kept as controls and 12 calves (6 per diet) received daily, per os, a combination of 17beta-boldenone (17beta-Bol) and androsta-1,4-dien-3,17-dione (ADD) for 38 days. The urinary elimination of 17 alpha-/17beta-boldenone conjugates (17 alpha/beta-Bol) and androsta-1,4-dien-3,17-dione (ADD) was followed by liquid chromatography-tandem mass spectrometry from all of the animals until slaughtering. In urine from treated animals, 17 alpha-Bol concentrations, despite a great variability, were greater than 17beta-Bol, both detected always as conjugates. At days 1, 2, and 3, the mean urine concentration of 17 alpha-Bol was higher than 12 ng/mL. A remarkable decrease was observed during the following days, but the 17 alpha-Bol concentration was still higher than the attention level of 2 ng/mL in 58% of the samples; the concentration of 17beta-Bol was around the action level of 1 ng/mL; two days after treatment withdrawal, no 17beta-Bol was detected in the urine. In urine from control animals, the 17 alpha-Bol concentration was strictly related to the phytosterol content of the diet, while, in urine from treated animals, the much higher 17 alpha-Bol levels were not modified by the production from diet precursors. The results confirmed that a 17 alpha-Bol level higher than 2 ng/mL should be considered as evidence of suspected illegal treatment and that the urinary excretion of 17beta-Bol is due to exogenous administration of 17beta-Bol. The discontinuous rate of elimination of both 17 alpha- and 17beta-Bol, despite the daily administration of 17beta-Bol plus ADD, indicates the necessity for further research to detect other urinary boldenone metabolites to strength surveillance strategy.

Porcine follicular fluids: Comparison of solid-phase extraction and matrix solid-phase dispersion for the GC–MS determination of hormones during follicular growth

The capabilities of solid-phase extraction (SPE) and matrix solid-phase dispersion (MSPD) for the determination of the hormones 17beta-estradiol, 2-hydroxyestradiol, 4-hydroxyestradiol and 2-methoxyestradiol by gas chromatography-mass spectrometry (GC-MS) in a very complex matrix like porcine follicular fluids were compared, thus proving the highest effectiveness of the SPE technique. Validation was carried out in terms of limit of quantitation (LOQ), precision, accuracy, recovery and stability. LOQ values in the low microg kg(-1) were achieved, with all the other parameters satisfying the acceptance criteria for the validation of bioanalytical methods. The applicability of the method to the determination of the hormones in porcine follicular fluids was demonstrated, thus allowing to observe an increase of the concentration of the hormones during the follicular growth.