A rapid screening assay for measuring urinary androsterone and etiocholanolone delta(13)C ( per thousand) values by gas chromatography/combustion/isotope ratio mass spectrometry

A simplified and accurate method for the analysis of urinary metabolites of testosterone-related steroids using gas chromatography/combustion/isotope ratio mass spectrometry

RATIONALE

The analysis of urinary metabolites of testosterone-related steroids through the measurement of their carbon isotopic signature (δ(13) C) by gas chromatography/combustion/mass spectrometry (GC/C/IRMS) is a confirmation method employed in doping control analyses. Stringent analytical conditions are essential to an accurate and precise analysis as well as the proper selection of the metabolites, which forms the basis of the refined method presented in this paper.

METHODS

In a simplified approach, following enzymatic hydrolysis and extraction from a relatively low volume of urine sample, a one-step high-performance liquid chromatography (HPLC) purification was developed for seven diagnostic urinary metabolites (TS) including testosterone itself, dehydroepiandrosterone, 5α- and 5β-androstanediol, epitestosterone, androsterone, etiocholanolone and two endogenous reference compounds (ERC), 5β-pregnanediol and 5α-androst-16-en-3β-ol. These steroids were pooled in three fractions and analyzed as such. With regards to the GC/C/IRMS analysis, a multi-level isotopic calibration using the 'identical treatment' principle was created.

RESULTS

The proposed isotopic calibration yielded results for purified reference steroids with a precision ≤0.15 and accuracy of ≤0.30 ‰ (between-assay, n = 26). Compared to other common endogenous reference compounds, those selected in this study had δ(13) C values close to the target metabolites which, along with the proposed isotopic calibration, produced narrow reference intervals within ± 3‰ for most diagnostic TS-ERC pairs, in compliance with the requirements of the World Anti-Doping Agency.

CONCLUSIONS

These carefully controlled analytical conditions are compatible with routine operations, affording accurate and precise results for the more diagnostically relevant metabolites such as testosterone itself and the 5α- and 5β-androstanediols. The values of the TS-ERC pairs measured in reference populations are described and the results from the routine testing of several hundreds of athletes' samples are discussed. Robust, this technique permitted the detection of adverse findings that would have been missed had these low level metabolites not been analyzed.

Use of isotope ratio mass spectrometry to differentiate between endogenous steroids and synthetic homologues in cattle: a review

Although substantial technical advances have been achieved during the past decades to extend and facilitate the analysis of growth promoters in cattle, the detection of abuse of synthetic analogs of naturally occurring hormones has remained a challenging issue. When it became clear that the exogenous origin of steroid hormones could be traced based on the (13)C/(12)C isotope ratio of the substances, GC/C/IRMS has been successfully implemented to this aim since the end of the past century. However, due to the costly character of the instrumental setup, the susceptibility of the equipment to errors and the complex and time consuming sample preparation, this method is up until now only applied by a limited number of laboratories. In this review, the general principles as well as the practical application of GC/C/IRMS to differentiate between endogenous steroids and exogenously synthesized homologous compounds in cattle will be discussed in detail, and will be placed next to other existing and to be developed methods based on isotope ratio mass spectrometry. Finally, the link will be made with the field of sports doping, where GC/C/IRMS has been established within the World Anti-Doping Agency (WADA) approved methods as the official technique to differentiate between exogenous and endogenous steroids over the past few years.

Systematic comparison of δ13C measurements of testosterone and derivative steroids in a freeze-dried urine candidate reference material for sports drug testing by gas chromatography/combustion/isotope ratio mass spectrometry and uncertainty evaluation using four different metrological approaches

An alternative calibration procedure for use when performing carbon isotope ratio measurements by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) has been developed. This calibration procedure does not rely on the corrections in-built in the instrument software, as the carbon isotope ratios of a sample are calculated from the measured raw peak areas. The method was developed for the certification of a urine reference material for sports drug testing, as the estimation of measurement uncertainty is greatly simplified. To ensure that the method is free from bias arising from the choice of calibration material and instrument, the carbon isotope ratios of steroids in urine extracts were measured using two different instruments in different laboratories, and three different reference materials (CU/USADA steroid standards from Brenna Laboratory, Cornell University; NIST RM8539 mineral oil; methane calibrated against NIST RM8560 natural gas). The measurements were performed at LGC and the Australian National Measurement Institute (NMI). It was found that there was no significant difference in measurement results when different instruments and reference materials were used to measure the carbon isotope ratio of the major testosterone metabolites androsterone and etiocholanolone, or the endogenous reference compounds pregnanediol, 11- ketoetiocholanolone and 11β-hydroxyandrosterone. Expanded measurement uncertainties at the 95% coverage probability ranged from 0.21‰ to 1.4‰, depending on analyte, instrument and reference material. The measurement results of this comparison were used to estimate a measurement uncertainty of δ(13)C for the certification of the urine reference material being performed on a single instrument using a single reference material at NMI.

Biochemical and physiological aspects of endogenous androgens

This review attempts to give a synopsis of the major aspects concerning the biochemistry of endogenous androgens, supplemented with several facets of physiology, particularly with respect to testosterone. Testosterone continues to be the most common adverse finding declared by World Anti-Doping Agency accredited laboratories, such samples having an augmented testosterone to epitestosterone ratio. Knowledge regarding the precursors and metabolism of endogenous testosterone is therefore fundamental to understanding many of the issues concerning doping with testosterone and its prohormones, including the detection of their administration. Further, adverse findings for nandrolone are frequent, but this steroid and 19-norandrostenedione are also produced endogenously, an appealing hypothesis being that they are minor by-products of the aromatization of androgens. At sports tribunals pertaining to adverse analytical findings of natural androgen administration, experts often raise issues that concern some aspect of steroid biochemistry and physiology. Salient topics included within this review are the origins and interconversion of endogenous androgens, the biosynthesis of testosterone and epitestosterone, the mechanism of aromatization, the molecular biology of the androgen receptor, the hypothalamic-pituitary-testicular axis, disturbances to this axis by anabolic steroid administration, the transport (binding) of androgens in blood, and briefly the metabolism and excretion of androgens.

The influence of diet on isotope ratio mass spectrometry values

OBJECTIVES

Athletes have increasingly used testosterone (T) and other endogenous anabolic steroids that cannot be detected by conventional gas chromatography-mass spectrometry. This led to gas chromatography-combustion-isotope ratio mass spectrometry(GC/C/IRMS), which measures the relative amount of 13C in urinary steroids. Because exogenous testosterone is relatively low in 13C content, this study will determine if consuming a diet low in 13C plants, such as soy, can be confused with a GC/C/IRMS-positive test for exogenous testosterone.

DESIGN

Cross-sectional study in which 22 vegetarians known to consume a diet depleted of 13C isotope were compared with a geographic control group of 14 subjects consuming a normal diet.

SETTING

Two distinct subject populations with respect to diet.

SUBJECTS

Subjects were recruited from a soy-based cooperative and control volunteers. Twenty-two of 24 research subjects completed the protocol compared with 14 of 22 control subjects.

INTERVENTIONS

Independent variables were delta13C IRMS values,urinary steroid profile, and isoflavone analysis.

MAIN OUTCOME MEASURES

Comparisons were made with respect to dietary analysis, isoflavones, and urinary steroid measurements using GC-C-IRMS.

RESULTS

The delta13C values for 2 major metabolites of T (androsterone and etiocholanolone) were lower for the vegetarians than the controls (P = 0.005). The vegetarians excreted a median of 23 micromol/d of total isoflavones compared with 2.7 micromol/d for the control group (P =0.0002).

CONCLUSIONS

The carbon isotope ratios of urinary testosterone metabolites of vegetarians consuming a diet that is markedly depleted of 13C content were lower than that of control subjects, but not low enough to result in World Anti-Doping Agency criteria for a positive IRMS analysis.

Drug testing data from the 2007 Pan American Games: delta13C values of urinary androsterone, etiocholanolone and androstanediols determined by GC/C/IRMS

The main purpose of this article is to show the application of the CG/C/IRMS in real time during competition in the steroid confirmation analysis. For this reason, this paper summarizes the results obtained from the doping control analysis during the period of the 2007 Pan American Games held in Rio de Janeiro, Brazil. Approximately 5600 athletes from 42 different countries competed in the games. Testing was performed in accordance to World Anti-Doping Agency (WADA) technical note for prohibited substances. This paper reports data where abnormal urinary steroid profiles, have been found with the screening procedures. One 8 mL urine sample was used for the analysis of five steroid metabolites with two separate analyses by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). Urine samples were submitted to GC/C/IRMS for confirmation analysis to determine the (13)C/(12)C ratio of selected steroids. Fifty-seven urine samples were analyzed by GC/C/IRMS and the delta(13)C values ( per thousand) of androsterone, etiocholanolone, 5beta-androstane-3alpha, 17beta-diol (5beta-diol), 5alpha-androstane-3alpha, 17beta-diol (5alpha-diol) and 5beta-pregnane-3alpha, 20alpha-diol (5beta-pdiol), the endogenous reference compound are presented. One urine sample with a testosterone/epitestosterone (T/E) ratio of 4.7 was confirmed to be positive of doping by GC/C/IRMS analysis. The delta values of 5beta-diol and 5alpha-diol were 3.8 and 10.8, respectively, compared to the endogenous reference compound 5beta-pdiol, which exceeded the WADA limit of 3 per thousand. The results obtained by CG/C/IRMS confirmation analyses, in suspicious samples, were conclusive in deciding whether or not a doping steroid violation had occurred.

Steroid isotopic standards for gas chromatography-combustion isotope ratio mass spectrometry (GCC-IRMS)

Carbon isotope ratio (CIR) analysis of urinary steroids using gas chromatography-combustion isotope ratio mass spectrometry (GCC-IRMS) is a recognized test to detect illicit doping with synthetic testosterone. There are currently no universally used steroid isotopic standards (SIS). We adapted a protocol to prepare isotopically uniform steroids for use as a calibrant in GCC-IRMS that can be analyzed under the same conditions as used for steroids extracted from urine. Two separate SIS containing a mixture of steroids were created and coded CU/USADA 33-1 and CU/USADA 34-1, containing acetates and native steroids, respectively. CU/USADA 33-1 contains 5alpha-androstan-3beta-ol acetate (5alpha-A-AC), 5alpha-androstan-3alpha-ol-17-one acetate (androsterone acetate, A-AC), 5beta-androstan-3alpha-ol-11, 17-dione acetate (11-ketoetiocholanolone acetate, 11k-AC) and 5alpha-cholestane (Cne). CU/USADA 34-1 contains 5beta-androstan-3alpha-ol-17-one (etiocholanolone, E), 5alpha-androstan-3alpha-ol-17-one (androsterone, A), and 5beta-pregnane-3alpha, 20alpha-diol (5betaP). Each mixture was prepared and dispensed into a set of about 100 ampoules using a protocol carefully designed to minimize isotopic fractionation and contamination. A natural gas reference material, NIST RM 8559, traceable to the international standard Vienna PeeDee Belemnite (VPDB) was used to calibrate the SIS. Absolute delta(13)C(VPDB) and Deltadelta(13)C(VPDB) values from randomly selected ampoules from both SIS indicate uniformity of steroid isotopic composition within measurement reproducibility, SD(delta(13)C)<0.2 per thousand. This procedure for creation of isotopic steroid mixtures results in consistent standards with isotope ratios traceable to the relevant international reference material.

Carbon isotope ratio (delta13C) values of urinary steroids for doping control in sport

The detection of steroids originating from synthetic precursors in relation to their chemically identical natural analogues has proven to be a significant challenge for doping control laboratories accredited by the World Anti-Doping Agency (WADA). Endogenous steroid abuse may be confirmed by utilising the atomic specificity of gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) that enables the precise measurement of differences in stable isotope ratios that arise as a result of fractionation patterns inherent in the source of steroids. A comprehensive carbon isotope ratio (delta(13)C) profiling study (n=1262) of urinary ketosteroids is reported that demonstrates the inter-individual variation that can be expected from factors such as diet, ethnicity, gender and age within and between different populations (13 countries). This delta(13)C distribution is shown by principal component analysis (PCA) to provide a statistical comparison to delta(13)C values observed following administration of testosterone enanthate. A limited collection of steroid diol data (n=100; consisting of three countries) is also presented with comparison to delta(13)C values of excreted testosterone to validate criteria for WADA accredited laboratories to prove doping offences.

Anabolic steroid use: patterns of use and detection of doping

Anabolic-androgenic steroids (AAS) were the first identified doping agents that have ergogenic effects and are being used to increase muscle mass and strength in adult males. Consequently, athletes are still using them to increase physical performance and bodybuilders are using them to improve size and cosmetic appearance. The prevalence of AAS use has risen dramatically over the last two decades and filtered into all aspects of society. Support for AAS users has increased, but not by the medical profession, who will not accept that AAS use dependency is a psychiatric condition. The adverse effects and potential dangers of AAS use have been well documented. AAS are used in sport by individuals who have acquired knowledge of the half-lives of specific drugs and the dosages and cycles required to avoid detection. Conversely, they are used by bodybuilders in extreme dosages with the intention of gaining muscle mass and size, with little or no regard for the consequences. Polypharmacy by self-prescription is prevalent in this sector. Most recently, AAS use has filtered through to 'recreational street drug' users and is the largest growth of drugs in this subdivision. They are taken to counteract the anorexic and cachectic effects of the illegal psychotropic street drugs. Screening procedures for AAS in World Anti-Doping Agency accredited laboratories are comprehensive and sensitive and are based mainly on gas chromatography-mass spectrometry, although liquid chromatography-mass spectrometry is becoming increasingly more valuable. The use of carbon isotope mass spectrometry is also of increasing importance in the detection of natural androgen administration, particularly to detect testosterone administration. There is a degree of contentiousness in the scenario of AAS drug use, both within and outside sport. AAS and associated doping agents are not illegal per se. Possession is not an offence, despite contravening sporting regulations and moral codes. Until AAS are classified in the same capacity as street drugs in the UK, where possession becomes a criminal offence, they will continue to attract those who want to win at any cost. The knowledge acquired by such work can only assist in the education of individuals who use such doping agents, with a view to minimizing health risks and hopefully once again create a level playing field in sport.

The application of carbon isotope ratio mass spectrometry to doping control

The administration of synthetic steroid copies is one of the most important issues facing sports. Doping control laboratories accredited by the World Anti-Doping Agency (WADA) require methods of analysis that allow endogenous steroids to be distinguished from their synthetic analogs in urine. The ability to measure isotope distribution at natural abundance with high accuracy and precision has increased the application of Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry (GC-C-IRMS) to doping control in recent years. GC-C-IRMS is capable of measuring the carbon isotope ratio (delta(13)C) of urinary steroids and confirm their synthetic origin based on the abnormal (13)C content. This tutorial describes some of the complexities encountered by obtaining valid delta(13)C measurements from GC-C-IRMS and the need for careful interpretation of all relevant information concerning an individual's metabolism in order to make an informed decision with respect to a doping violation.

Factors influencing the steroid profile in doping control analysis

Steroid profiling is one of the most versatile and informative screening tools for the detection of steroid abuse in sports drug testing. Concentrations and ratios of various endogenously produced steroidal hormones, their precursors and metabolites including testosterone (T), epitestosterone (E), dihydrotestosterone (DHT), androsterone (And), etiocholanolone (Etio), dehydroepiandrosterone (DHEA), 5alpha-androstane-3alpha,17beta-diol (Adiol), and 5beta-androstane-3alpha,17beta-diol (Bdiol) as well as androstenedione, 6alpha-OH-androstenedione, 5beta-androstane-3alpha,17alpha-diol (17-epi-Bdiol), 5alpha-androstane-3alpha,17alpha-diol (17-epi-Adiol), 3alpha,5-cyclo-5alpha-androstan-6beta-ol-17-one (3alpha,5-cyclo), 5alpha-androstanedione (Adion), and 5beta-androstanedione (Bdion) add up to a steroid profile that is highly sensitive to applications of endogenous as well as synthetic anabolic steroids, masking agents, and bacterial activity. Hence, the knowledge of factors that do influence the steroid profile pattern is a central aspect, and pharmaceutical (application of endogenous steroids and various pharmaceutical preparations), technical (hydrolysis, derivatization, matrix), and biological (bacterial activities, enzyme side activities) issues are reviewed.

delta13C-values of endogenous urinary steroids

By means of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) urinary steroids obtained from a reference population of 56 subjects were analyzed for their (13)C/(12)C-ratios. The analytes encompassed androsterone (A), etiocholanolone (E), 11beta-hydroxyetiocholanolone (OHE), 11beta-hydroxyandrosterone (OHA), and 5beta-pregnane- 3alpha,20alpha-diol (PD). A and E represent androgen metabolites (AM). PD, OHE, and OHA have sources independent from androgen metabolism. The delta(13)C-values of the latter compounds may be compared to those of AM in order to detect doping with synthetic androgens and thus may serve as endogenous reference compounds (ERC). In order to allow for classification of conspicuous samples, reference ranges and limits were calculated for delta(13)C-values of selected steroids and differences hereof (Delta(13)C-values). When A is compared to ERCs, Delta(13)C-values larger than 3 per thousand are very unlikely. A set of additional parameters was surveyed by a questionnaire. Several factors turned out to exert significant influence on the delta(13)C-values of urinary steroids. These encompass the identity of the steroid itself, sex, oral contraception, travels, and physical activity.

Detection of dehydroepiandrosterone misuse by means of gas chromatography- combustion-isotope ratio mass spectrometry

According to World Anti-Doping Agency (WADA) rules (WADA Technical Document-TD2004EAAS) urine samples containing dehydroepiandrosterone (DHEA) concentrations greater than 100 ng ML(-1) shall be submitted to isotope ratio mass spectrometry (IRMS) analysis. The threshold concentration is based on the equivalent to the glucuronide, and the DHEA concentrations have to be adjusted for a specific gravity value of 1.020. In 2006, 11,012 doping control urine samples from national and international federations were analyzed in the Cologne doping control laboratory, 100 (0.9%) of them yielding concentrations of DHEA greater than 100 ng mL(-1). Sixty-eight percent of the specimens showed specific gravity values higher than 1.020, 52% originated from soccer players, 95% were taken in competition, 85% were male urines, 99% of the IRMS results did not indicate an application of testosterone or related prohormones. Only one urine sample was reported as an adverse analytical finding having 319 ng mL(-1) DHEA (screening result), more than 10,000 ng mL(-1) androsterone and depleted carbon isotope ratio values for the testosterone metabolites androsterone and etiocholanolone. Statistical evaluation showed significantly different DHEA concentrations between specimens taken in- and out-of- competition, whereas females showed smaller DHEA values than males for both types of control. Also a strong influence of the DHEA excretion on different sport disciplines was detectable. The highest DHEA values were detected for game sports (soccer, basketball, handball, ice hockey), followed by boxing and wrestling. In 2007, 6622 doping control urine samples were analyzed for 3alpha,5-cyclo-5alpha-androstan-6beta-ol-17-one (3alpha,5-cyclo), a DHEA metabolite which was described as a useful gas chromatography-mass spectrometry (GC-MS) screening marker for DHEA abuse. Nineteen urine specimens showed concentrations higher than the suggested threshold of 140 ng mL(-1), six urine samples yielded additionally DHEA concentrations higher than 100 ng mL(-1), none of them showing positive IRMS findings. These results should be taken into consideration in future discussions about threshold values for endogenous steroids in doping control.

Mass spectrometry and isotopes: a century of research and discussion

In 1815, the British physician William Prout had advanced the theory that the molecular masses of elements were multiples of the mass of hydrogen. This "whole number rule" (and especially deviations from it) played an important role in the discussion whether elements could be mixtures of isotopes. F. Soddy's discovery (1910) that lead obtained by decay of uranium and of thorium differed in mass was considered a peculiarity of radioactive materials. The question of the existence of isotopes came up when the instruments developed by J.J. Thomson and by W. Wien to study cathode and canal rays by deflection in electric and magnetic fields were steadily improved. In 1913, Thomson mentioned a weak line at mass 22 accompanying the expected one at mass 20 when he analyzed the mass spectrum of neon. Subsequently Aston obtained the mass spectrum of chlorine with masses at 35 and 37. Still in 1921, Thomson objected heavily to the idea of isotopes. The isotope problem was finally settled, but more accurate mass measurements showed that even isotopic weights differed to some extent from the whole numbers. Based on earlier ideas of P. Langevin and J.-L. Costa, F.W. Aston and A.J. Dempster developed the idea of packing fractions and mass defects due to the transformation of a portion of the matter comprising the atomic nucleus into energy. While the determination of the exact isotopic masses had improved over the years, the accurate determination of isotopic abundances remained a problem as long as photographic recording was used. Here especially A.O. Nier pioneered using dual collectors and compensation measurements. This was the prerequisite for the discovery that isotopic ratios varied somewhat in nature. M. Dole discovered the fractionation of oxygen isotopes by photosynthesis and respiration. Today 13C/12C-ratios are employed to detect adulterations of food and in doping analysis, and 14C/13C-ratios obtained by accelerator mass spectrometry are used for dating historical objects, just to give some examples.

Elevated and similar urinary testosterone/epitestosterone ratio in all samples of a competition testing: suspicion of a manipulation

The case of seven urine samples collected for anti-doping purposes during a cycling stage race with moderately elevated testosterone and epitestosterone ratio (T/E) is reported. The very low probability of having all seven urine samples with such similar elevated T/E ratio (from 3.2 to 4.7) was very suspicious. Different pattern classification tools were tested to categorize the most similar steroid profiles, but none of the models enabled a clear classification of the different urine samples. Subsequently, genetic profiling of all urine samples was performed and demonstrated that three of the seven samples were collected from the same cyclist. Finally, the International Federation confirmed DNA profiling results. This suggests that urinary steroid data using several methodologies are not appropriate for identification purposes and to an extent not unique to individuals.

Searching for new markers of endogenous steroid administration in athletes: “looking outside the metabolic box”

A simple means of detecting the abuse of steroids that also occur naturally is a problem facing doping control laboratories. Specific markers are required to allow the detection of the administration of these steroids. These markers are commonly measured using a set of data obtained from the screening of samples by gas chromatography-mass spectrometry (GC-MS). Doping control laboratories further need to confirm identified abuse using techniques such as gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). An interesting urinary species was found while following the pharmacokinetics and changes to the steroid profile from single and multiple oral doses of the International Olympic Committee/World Anti Doping Agency (IOC/WADA) prohibited substance, dehydroepiandrosterone (DHEA). The urine samples collected from the administration studies were subject to GC-MS and GC-C-IRMS steroid analysis following cleanup by solid phase extraction techniques. A useful urinary product of DHEA administration was detected in the urine samples from each of the administration studies and was identified by GC-MS experiments to be 3alpha,5-cyclo-5alpha-androstan-6beta-ol-17-one (3alpha,5-cyclo). This compound occurs naturally but the concentrations of 3alpha,5-cyclo were elevated following both the single DHEA administration (up to 385 ng/mL) and multiple DHEA administrations (up to 1240 ng/mL), in relation to those observed prior to these administrations (70 and 80 ng/mL, respectively). A reference distribution of urine samples collected from elite athletes (n = 632) enabled the natural concentration range of 3alpha,5-cyclo to be established (0-280 ng/mL), with a mean concentration of 22 ng/mL. Based on this an upper 3alpha,5-cyclo concentration limit of 140 ng/mL is proposed as a GC-MS screening marker of DHEA abuse in athletes. GC-C-IRMS analysis revealed significant 13C depletion of 3alpha,5-cyclo following DHEA administration. In the single administration study, the delta13C value of 3alpha,5-cyclo changed from -24.3 per thousand to a minimum value of -31.1 per thousand at 9 h post-administration, before returning to its original value after 48 h. The multiple administration study had a minimum delta13C 3alpha,5-cyclo of -33.9 per thousand during the administration phase in contrast to the initial value of -24.2 per thousand. Preliminary studies have shown 3alpha,5-cyclo to most likely be produced from DHEA sulfate found at high levels in urine. The complementary use of GC-MS and GC-C-IRMS to identify new markers of steroid abuse and the application of screening criteria incorporating such markers could also be adapted by doping control laboratories to detect metabolites of androstenedione, testosterone and dihydrotestosterone abuse.

Fast screening of anabolic steroids and other banned doping substances in human urine by gas chromatography/tandem mass spectrometry

A fast and sensitive method for the comprehensive screening of anabolic agents and other banned doping substances using gas chromatography/tandem mass spectrometry (GC/MS/MS) with an external ionization ion trap mass spectrometer is presented. The method takes advantage of the resolving power of MS/MS to eliminate background interferences, thus speeding up the chromatographic analysis. For each compound, different fragmentation reactions were studied and their collision energies optimized to obtain the best sensitivity in terms of their signal-to-noise ratio (S/N). A dramatic reduction in overall analysis time was achieved compared with other common approaches. More than 50 substances could finally be monitored in less than 7.4 min with detection limits (S/N >3) lower than 0.5 ng ml(-1) for most of the compounds with special sensitivity requirements according to the International Olympic Committee (IOC). A validation procedure for qualitative analysis was performed. The selectivity of the method showed that no interfering peaks were observed at the retention time of the analytes. Good intermediate precision, below 25% for most of the compounds, and robustness were observed. The optimized method was successfully applied to analyse more than 100 real human urine samples with optimum sensitivity and specificity rates.

Detection of Epitestosterone Doping by Isotope Ratio Mass Spectrometry

Background: Epitestosterone is prohibited by sport authorities because its administration will lower the urinary testosterone/epitestosterone ratio, a marker of testosterone administration. A definitive method for detecting epitestosterone administration is needed.

Methods: We developed a gas chromatography-combustion-isotope ratio mass spectrometry method for measuring the δ13C values for urinary epitestosterone. Sample preparation included deconjugation with β-glucuronidase, solid-phase extraction, and semipreparative HPLC. Epitestosterone concentrations were determined by gas chromatography-mass spectrometry for urines obtained from a control group of 456 healthy males. Epitestosterone δ13C values were determined for 43 control urines with epitestosterone concentrations ≥40 μg/L (139 nmol/L) and 10 athletes’ urines with epitestosterone concentrations ≥180 μg/L (624 nmol/L), respectively.

Results: The log epitestosterone concentration distribution was gaussian [mean, 3.30; SD, 0.706; geometric mean, 27.0 μg/L (93.6 nmol/L)]. The δ13C values for four synthetic epitestosterones were low (less than or equal to −30.3‰) and differed significantly (P &lt;0.0001). The SDs of between-assay precision studies were low (≤0.73‰). The mean δ13C values for urine samples obtained from 43 healthy males was −23.8‰ (SD, 0.93‰). Nine of 10 athletes’ urine samples with epitestosterone concentrations &gt;180 μg/L (624 nmol/L) had δ13C values within ± 3 SD of the control group. The δ13C value of epitestosterone in one sample was −32.6‰ (z-score, 9.4), suggesting that epitestosterone was administered. In addition, the likelihood of simultaneous testosterone administration was supported by low δ13C values for androsterone and etiocholanolone.

Conclusions: Determining δ13C values for urinary epitestosterone is useful for detecting cases of epitestosterone administration because the mean δ13C values for a control group is high (−23.8‰) compared with the δ13C values for synthetic epitestosterones.

Gas chromatography/combustion/isotope ratio mass spectrometry to control the misuse of androgens in breeding animals: new derivatisation method applied to testosterone metabolites and precursors in urine samples

A new derivatisation reaction applied to the analysis of steroids by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) was studied. The trimethylsilylated steroids were characterised by well-resolved chromatographic signals, no peak tailing, reproducible 13C/12C measurements (0.32 per thousand, n = 28), good signal-to-noise ratio and absolute intensity (5 x 10(-9) A, 20 ng), and a slow degradation of copper oxide pellets in the combustion furnace. In addition, two new metabolites and one precursor of testosterone in bovine have been brought into consideration and used for GC/C/IRMS measurements, namely, 3beta-hydroxy-5alpha-androstan-17-one (epiandrosterone), 3beta,17alpha-dihydroxy-5alpha-androstane, and 3beta,17alpha-dihydroxy-5-androstene. The new findings have been applied to an elimination study in bovine of testosterone metabolites after an intramuscular injection of testosterone enanthate. Significant differences (up to 4 per thousand) between testosterone metabolites and precursor were detectable at least three weeks after administration.