Michaël Polet

Development of a GC/C/IRMS method – Confirmation of a novel steroid profiling approach in doping control

In doping control, an athlete can only be convicted with the misuse with endogenous steroids like testosterone (T), if abnormal values of steroid metabolites and steroid ratios are observed and if the subsequent analysis with isotope ratios mass spectrometry (IRMS) confirms the presence of exogenously administered androgens. In this work, we compare the results of a novel steroid profiling approach with the performance an in-house developed IRMS method. The developed IRMS has the advantage over other methods to be relatively short in time and with target compounds androsterone, etiocholanolone, 5β-androstane 3α,17β-diol and 5α-androstane 3α,17β-diol. Pregnanediol was used as an endogenous reference compound (ERC). Reference limits for the IRMS values were established and applied as decision limits for the evaluation of excretion urine from administration with oral T, T-gel, dihydrotestosterone (DHT) - gel and dehydroepiandrosterone (DHEA). Results indicated the importance of both androstanediols as important IRMS markers where relative values compared to an ERC (Δδ(13)C) yielded better detection accuracy than absolute δ(13)C-values. The detection times of all administered endogenous steroids were evaluated using the proposed thresholds. The results of traditional steroid profiling and a new approach based upon minor steroid metabolites monitoring introduced in a longitudinal framework were evaluated with IRMS. With traditional steroid profiling methods, 95% of the atypical samples could be confirmed whereas an additional 74% of IRMS confirmed was provided by a new biomarkers strategy. These results prove that the other steroid profiling strategies can improve the efficiency in detection of misuse with endogenous steroids.

Development of a sensitive GC-C-IRMS method for the analysis of androgens

The administration of anabolic steroids is one of the most important issues in doping control and is detectable through a change in the carbon isotopic composition of testosterone and/or its metabolites. Gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS), however, remains a very laborious and expensive technique and substantial amounts of urine are needed to meet the sensitivity requirements of the IRMS. This can be problematic because only a limited amount of urine is available for anti-doping analysis on a broad spectrum of substances. In this work we introduce a new type of injection that increases the sensitivity of GC-C-IRMS by a factor of 13 and reduces the limit of detection, simply by using solvent vent injections instead of splitless injection. This drastically reduces the amount of urine required. On top of that, by only changing the injection technique, the detection parameters of the IRMS are not affected and there is no loss in linearity.

Metabolism of methylstenbolone studied with human liver microsomes and the uPA⁺/⁺-SCID chimeric mouse model.

Anti-doping laboratories need to be aware of evolutions on the steroid market and elucidate steroid metabolism to identify markers of misuse. Owing to ethical considerations, in vivo and in vitro models are preferred to human excretion for nonpharmaceutical grade substances. In this study the chimeric mouse model and human liver microsomes (HLM) were used to elucidate the phase I metabolism of a new steroid product containing, according to the label, methylstenbolone. Analysis revealed the presence of both methylstenbolone and methasterone, a structurally closely related steroid. Via HPLC fraction collection, methylstenbolone was isolated and studied with both models. Using HLM, 10 mono-hydroxylated derivatives (U1-U10) and a still unidentified derivative of methylstenbolone (U13) were detected. In chimeric mouse urine only di-hydroxylated metabolites (U11-U12) were identified. Although closely related, neither methasterone nor its metabolites were detected after administration of isolated methylstenbolone. Administration of the steroid product resulted mainly in the detection of methasterone metabolites, which were similar to those already described in the literature. Methylstenbolone metabolites previously described were not detected. A GC-MS/MS multiple reaction monitoring method was developed to detect methylstenbolone misuse. In one out of three samples, previously tested positive for methasterone, methylstenbolone and U13 were additionally detected, indicating the applicability of the method.

Profiling of urinary formestane and confirmation by isotope ratio mass spectrometry.

Formestane (F, androst-4-en-4-ol-3,17-dione) is an irreversible aromatase inhibitor with the ability to suppress the estrogen production from anabolic steroids. Consequently, F is mentioned on the World Anti-Doping Agency (WADA) prohibited list and because studies have shown that F is produced endogenously in small amounts, a threshold for urinary excreted F of 150 ng/mL was introduced. Lower concentrations could be due to endogenous production and need further investigation to prove the exact origin through determination of the carbon isotope ratio. However, because the current screening methods are a lot more sensitive, F is detected in practically every urine sample. A strict implementation of this WADA rule would imply that almost every urine sample needs additional investigation to verify an exogenous or endogenous origin. The main aim of this study was to propose and introduce a lower concentration limit of 25 ng/mL beneath which the detected F is considered as being endogenous and no further investigation is needed. The data presented in this paper suggests that this threshold provides a good balance between a sufficiently large detection window and not having to perform isotope ratio mass spectrometry (IRMS) analyses on negative urine samples.

Improved sensitivity by use of gas chromatography-positive chemical ionization triple quadrupole mass spectrometry for the analysis of drug related substances.

In 2013, the World Anti-Doping Agency (WADA) drastically lowered the minimum required performance levels (MRPLs) of most doping substances, demanding a substantial increase in sensitivity of the existing methods. For a number of compounds, conventional electron impact ionization gas chromatography tandem mass spectrometry (GC-EI-MS/MS) is often no longer sufficient to reach these MRPLs and new strategies are required. In this study, the capabilities of positive ion chemical ionization (PICI) GC-MS/MS are investigated for a wide range of drug related compounds of various classes by injection of silylated reference standards. Ammonia as PICI reagent gas had superior characteristics for GC-MS/MS purposes than methane. Compared to GC-EI-MS/MS, PICI (with ammonia as reagent gas) provided more selective ion transitions and consequently, increased sensitivity by an average factor of 50. The maximum increase (by factor of 500-1000) was observed in the analysis of stimulants, namely chlorprenaline, furfenorex and phentermine. In total, improved sensitivity was obtained for 113 out of 120 compounds. A new GC-PICI-MS/MS method has been developed and evaluated for the detection of a wide variety of exogenous doping substances and the quantification of endogenous steroids in urine in compliance with the required MRPLs established by WADA in 2013. The method consists of a hydrolysis and extraction step, followed by derivatization and subsequent 1μL pulsed splitless injection on GC-PICI-MS/MS (16min run). The increased sensitivity allows the set up of a balanced screening method that meets the requirements for both quantitative and qualitative compounds: sufficient capacity and resolution in combination with high sensitivity and short analysis time. This resulted in calibration curves with a wide linear range (e.g., 48-9600ng/mL for androsterone and etiochanolone; all r(2)>0.99) without compromising the requirements for the qualitative compounds.

Gas chromatography/chemical ionization triple quadrupole mass spectrometry analysis of anabolic steroids: ionization and collision-induced dissociation behavior

RATIONALE The detection of new anabolic steroid metabolites and new designer steroids is a challenging task in doping analysis. Switching from electron ionization gas chromatography triple quadrupole mass spectrometry (GC/EI-MS/MS) to chemical ionization (CI) has proven to be an efficient way to increase the sensitivity of GC/MS/MS analyses and facilitate the detection of anabolic steroids. CI also extends the possibilities of GC/MS/MS analyses as the molecular ion is retained in its protonated form due to the softer ionization. In EI it can be difficult to find previously unknown but expected metabolites due to the low abundance or absence of the molecular ion and the extensive (and to a large extent unpredictable) fragmentation. The main aim of this work was to study the CI and collision-induced dissociation (CID) behavior of a large number of anabolic androgenic steroids (AAS) as their trimethylsilyl derivatives in order to determine correlations between structures and CID fragmentation. Clarification of these correlations is needed for the elucidation of structures of unknown steroids and new metabolites. METHODS The ionization and CID behavior of 65 AAS have been studied using GC/CI-MS/MS with ammonia as the reagent gas. Glucuronidated AAS reference standards were first hydrolyzed to obtain their free forms. Afterwards, all the standards were derivatized to their trimethylsilyl forms. Full scan and product ion scan analyses were used to examine the ionization and CID behavior. RESULTS Full scan and product ion scan analyses revealed clear correlations between AAS structure and the obtained mass spectra. These correlations were confirmed by analysis of multiple hydroxylated, methylated, chlorinated and deuterated analogs. CONCLUSIONS AAS have been divided into three groups according to their ionization behavior and into seven groups according to their CID behavior. Correlations between fragmentation and structure were revealed and fragmentation pathways were postulated.

Studies on the minor metabolite 6a-hydroxy-androstenedione for doping control purposes and its contribution to the steroid profile.

Recent publications have shown that the concentrations of minor metabolites such as formestane and 6a-hydroxy-androstenedione (6aOHADION) are import parameters, capable of increasing the specificity and efficiency of steroid abuse screening. The importance of such minor metabolites has been recognized for some time, but setting up concentration thresholds is not that straightforward with a single quadrupole gas chromatograph mass spectrometer (GC-MS) because of the low concentrations; this is especially the case for 6aOH-ADION. The main aim of this study was to propose a concentration threshold above which the detected 6aOH-ADION is considered suspicious and isotope ratio mass spectrometry (IRMS) is recommended. Routine doping control samples (2128) from athletes that entered our lab and were not found suspicious for the intake of any doping substance were used to determine the baseline concentrations of 6a-OH-ADION. For this purpose, the more sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS) was used, capable of quantifying these low concentrations with high reliability. A urinary concentration threshold of 5 ng/mL was set. Concentrations above this threshold are considered suspicious and are forwarded to IRMS for confirmation in routine practice. In addition, an IRMS method was developed, capable of determining the 13C value of 6aOH-ADION. If a urine sample has an elevated 6aOH-ADION concentration and normal 13C values for the traditional IRMS target compounds, we are still able to check the 13C value of 6aOH-ADION. Six excretion studies were executed to stress the applicability of the threshold by visualizing the concentration and δ13C value time profiles of 6aOH-ADION.

Efficient approach for the detection and identification of new androgenic metabolites by applying SRM GC-CI-MS/MS: a methandienone case study.

Identification of anabolic androgenic steroids (AAS) is a vital issue in doping control and toxicology, and searching for metabolites with longer detection times remains an important task. Recently, a gas chromatography chemical ionization triple quadrupole mass spectrometry (GC-CI-MS/MS) method was introduced, and CI, in comparison with electron ionization (EI), proved to be capable of increasing the sensitivity significantly. In addition, correlations between AAS structure and fragmentation behavior could be revealed. This enables the search for previously unknown but expected metabolites by selection of their predicted transitions. The combination of both factors allows the setup of an efficient approach to search for new metabolites. The approach uses selected reaction monitoring which is inherently more sensitive than full scan or precursor ion scan. Additionally, structural information obtained from the structure specific CI fragmentation pattern facilitates metabolite identification. The procedure was demonstrated by a methandienone case study. Its metabolites have been studied extensively in the past, and this allowed an adequate evaluation of the efficiency of the approach. Thirty three metabolites were detected, including all relevant previously discovered metabolites. In our study, the previously reported long-term metabolite (18-nor-17β-hydroxymethyl,17α-methyl-androst-1,4,13-trien-3-one) could be detected up to 26 days by using GC-CI-MS/MS. The study proves the validity of the approach to search for metabolites of new synthetic AAS and new long-term metabolites of less studied AAS and illustrates the increase in sensitivity by using CI. Copyright

Potential of saliva steroid profiling for the detection of endogenous steroid abuse: Reference thresholds for oral fluid steroid concentrations and ratios

Urine and blood samples are the primary matrices for the detection of exogenous substances in doping control and toxicology. Although these matrices are, in general, very suitable for a wide range of substances, they do show some issues in particular cases. Here, alternative matrices may provide an answer. In this work, a quantitative method for steroid profiling (5 endogenous steroids and their ratios) in oral fluid was developed and validated. In total, 826 saliva samples were analyzed, and inter-individual reference population thresholds for saliva steroid profile parameters were set up. Alterations of this steroid profile after administration of naturally occurring anabolic androgenic steroids (e.g. testosterone (T) or dehydroepiandrosterone (DHEA)) were investigated. In addition, intra-individual short and long-term natural fluctuations were investigated. For longitudinal monitoring in oral fluid, steroid profile ratios (e.g., T/DHEA) were superior to absolute concentrations due to lower susceptibility towards the diurnal pattern. For the detection of a transdermal application of T, the salivary parameter T/DHEA proved to have the highest sensitivity. In contrast with the current screening procedures in urine, there is no need for an additional expensive and time-consuming isotope ratio mass spectrometry confirmation procedure to unequivocally attribute the elevated parameter to an exogenous origin.

Identification and confirmation of diuretics and masking agents in urine by turbulent flow online solid-phase extraction coupled with liquid chromatography-triple quadrupole mass spectrometry for doping control

Diuretics can be misused to force diuresis to achieve weight loss or to mask the intake of a prohibited substance and are therefore prohibited by the World Anti-Doping Agency (WADA). For similar reasons other masking agents (vaptans, probenecid, etc.) are also prohibited by the WADA. The currently employed methods to detect diuretics in urine use extraction or dilute-and-shoot, combined with 1D- liquid chromatography (LC) high resolution mass spectrometry (MS) or LC-triple quadrupole MS. Dilute-and-shoot methods save time and work, but these methods encounter some problems (e.g., peak drift and matrix effect). Therefore, a 2D-LC-MS/MS application was developed, validated and evaluated as an alternative. The effect of a turbulent flow rate was studied by loading samples under different conditions and the turbulent flow rate was found to be more effective in removing matrix interferences. A correlation with the specific gravity was observed. A turbulent flow online solid phase extraction (SPE) method combined with LC-MS/MS for the detection of 50 diuretics and masking agents was developed and validated for identification purposes. This method combines the advantages of dilute-and-shoot while solving the issues of matrix effect and retention time shift. Furthermore, the presented method is compliant with WADAs identification criteria and can hence be used for screening and/or confirmation.