Qualitative detection of desmopressin in plasma by liquid chromatography-tandem mass spectrometry.

This work describes a liquid chromatography-electrospray tandem mass spectrometry method for detection of desmopressin in human plasma in the low femtomolar range. Desmopressin is a synthetic analogue of the antidiuretic hormone arginine vasopressin and it might be used by athletes as a masking agent in the framework of blood passport controls. Therefore, it was recently added by the World Anti-Doping Agency to the list of prohibited substances in sport as a masking agent.

Quantitative detection of inhaled salmeterol in human urine and relevance to doping control analysis.

Salmeterol is a frequently prescribed β₂-agonist used for the treatment of asthma. Due to performance-enhancing effects of some β₂-agonists, salmeterol appears on the prohibited list published by the World Anti-Doping Agency and its therapeutic use is allowed but restricted to inhalation. Because the data on urinary concentrations originating from therapeutic use are limited, no discrimination can be made between use and abuse when a routine sample is found to contain salmeterol.

Comparison between triple quadrupole, time of flight and hybrid quadrupole time of flight analysers coupled to liquid chromatography for the detection of anabolic steroids in doping control analysis.

Triple quadrupole (QqQ), time of flight (TOF) and quadrupole-time of flight (QTOF) analysers have been compared for the detection of anabolic steroids in human urine. Ten anabolic steroids were selected as model compounds based on their ionization and the presence of endogenous interferences. Both qualitative and quantitative analyses were evaluated.

A fast, comprehensive screening method for doping agents in urine by gas chromatography-triple quadrupole mass spectrometry.

The use of performance enhancing drugs in sports is prohibited. For the detection of misuse of such substances gas chromatography or liquid chromatography coupled to mass spectrometry are the most frequently used detection techniques. In this work the development and validation of a fast gas chromatography tandem mass spectrometric method for the detection of a wide range of doping agents is described.

Population based evaluation of a multi-parametric steroid profiling on administered endogenous steroids in single low dose.

Steroid profiling provides valuable information to detect doping with endogenous steroids. Apart from the traditionally monitored steroids, minor metabolites can play an important role to increase the specificity and efficiency of current detection methods. The applicability of several minor steroid metabolites was tested on administration studies with low doses of oral testosterone (T), T gel, dihydrotestosterone (DHT) gel and oral dehydroepiandrosterone (DHEA).

Combination of liquid-chromatography tandem mass spectrometry in different scan modes with human and chimeric mouse urine for the study of steroid metabolism.

Anabolic steroids are among the most frequently detected compounds in doping analysis. They are extensively metabolized and therefore an in-depth knowledge about steroid metabolism is needed. In this study, a liquid chromatography tandem mass spectometry (LC-MS/MS) method based on a precursor ion scan with a uPA-SCID mouse with humanized liver (a chimeric mouse) was explored for the detection of steroid metabolism.

Steroid metabolism in chimeric mice with humanized liver.

Anabolic androgenic steroids are considered to be doping agents and are prohibited in sports. Their metabolism needs to be elucidated to allow for urinary detection by gas chromatography-mass spectrometry (GC-MS) or liquid chromatography-tandem mass spectrometry (LC-MS/MS). Steroid metabolism was assessed using uPA(+/+) SCID mice with humanized livers (chimeric mice).

beta-Adrenergic stimulation.

Two groups of substances which stimulate the adrenergic system are listed as prohibited by the World Anti-Doping Agency. Stimulants are prohibited in-competition only and beta(2)-agonists are prohibited in- and out-of-competition. While beta(2)-agonists act directly on the target receptors, sympathomimetic amines can exert their action directly and indirectly.

Reference ranges for urinary concentrations and ratios of endogenous steroids, which can be used as markers for steroid misuse, in a Caucasian population of athletes.

The detection of misuse with naturally occurring steroids is a great challenge for doping control laboratories. Intake of natural anabolic steroids alters the steroid profile. Thus, screening for exogenous use of these steroids can be established by monitoring a range of endogenous steroids, which constitute the steroid profile, and evaluate their concentrations and ratios against reference ranges.

The uPA(+/+)-SCID mouse with humanized liver as a model for in vivo metabolism of 4-androstene-3,17-dione.

The metabolism in primary human hepatocyte cultures often deviates from that in clinical studies, which in turn are hampered by ethical constraints. Here the use of urokinase-type plasminogen activator-severe combined immunodeficiency [uPA(+/+)-SCID] mice transplanted with human hepatocytes was investigated as a model for in vivo metabolic studies. The urinary excretion profile after oral administration of 4-androstene-3,17-dione (AD) in chimeric mice was investigated by using gas chromatography-mass spectrometry detection and was compared with previously reported metabolites of AD in humans and cell cultures.

Detection and characterization of a new metabolite of 17alpha-methyltestosterone.

The misuse of the anabolic steroid methyltestosterone is currently routinely monitored in doping control laboratories by gas chromatography-mass spectrometry (GC-MS) of two of its metabolites: 17alpha-methyl-5beta-androstane-3alpha,17beta-diol and 17alpha-methyl-5alpha-androstane-3alpha,17beta-diol. Because of the absence of any easy ionizable moiety, these metabolites are poorly detectable using liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI). In this study, the metabolism of methyltestosterone has been reinvestigated by the use of a precursor ion scan method in LC-ESI-MS/MS.

uPA+/+-SCID mouse with humanized liver as a model for in vivo metabolism of exogenous steroids: methandienone as a case study.

Background: Adequate detection of designer steroids in the urine of athletes is still a challenge in doping control analysis and requires knowledge of steroid metabolism. In this study we investigated whether uPA(+/+)-SCID mice carrying functional primary human hepatocytes in their liver would provide a suitable alternative small animal model for the investigation of human steroid metabolism in vivo.

Methods: A quantitative method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed and validated for the urinary detection of 7 known methandienone metabolites.

Detection and structural investigation of metabolites of stanozolol in human urine by liquid chromatography tandem mass spectrometry.

The applicability of LC-MS/MS in precursor ion scan mode for the detection of urinary stanozolol metabolites has been studied. The product ion at m/z 81 has been selected as specific for stanozolol metabolites without a modification in A- or N-rings and the product ions at m/z 97 and 145 for the metabolites hydroxylated in the N-ring and 4-hydroxy-stanozolol metabolites, respectively. Under these conditions, the parent drug and up to 15 metabolites were found in a positive doping test sample.

Quantification of testosterone undecanoate in human hair by liquid chromatography-tandem mass spectrometry.

Testosterone undecanoate (T-C11) can be used by athletes in order to improve performance. After oral intake, T-C11 is rapidly metabolized, hampering discrimination between exogenous and endogenous testosterone. A possible alternative is to detect the intact ester in hair.

Evaluation of different scan methods for the urinary detection of corticosteroid metabolites by liquid chromatography tandem mass spectrometry.

Different approaches for the non-target detection of corticosteroids in urine have been evaluated. As a result of previous studies about the ionization (positive/negative) and fragmentation of corticosteroids, several methods based on both precursor ion (PI) and neutral loss (NL) scans are proposed. The applicability of these methods was checked by the injection of a standard solution containing 19 model compounds.

Collision-induced dissociation of 3-keto anabolic steroids and related compounds after electrospray ionization. Considerations for structural elucidation.

The collision-induced dissociation of forty-one 3-keto anabolic steroids and related compounds has been studied using both triple quadrupole (QqQ) and hybrid quadrupole-time of flight (QTOF) instruments. Due to the complexity of the product ion spectra of these analytes, which generate a large number of ions, only two specific regions were studied in depth: the product ions near the precursor ion (m/z > or =M-100) and the most abundant product ions at a collision energy of 30 eV. Accurate mass measurements were used in order to obtain an unequivocal assignment of the empirical formula and the origin of each selected product ion.

Declared use of medication in sports.

Objective: To assess and compare the prevalence of declared medication, such as corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs), beta2-agonists, narcotic analgesics, anaesthetics, and antidepressant drugs, in time and between different sports among athletes tested for doping control in a 4-year period.

Design: Survey study.

Setting: Belgium.

Direct quantification of steroid glucuronides in human urine by liquid chromatography-electrospray tandem mass spectrometry.

A method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the direct quantification of glucuronides of testosterone (TG), epitestosterone (EPG), androsterone (AG) and etiocholanolone (ETG) has been developed. The method allowed for the direct determination of these analytes avoiding hydrolysis and derivatization, which are usual steps in commonly used methods based on gas chromatography-mass spectrometry (GC-MS). The electrospray ionization and the product ion spectra of the glucuronides have been studied in order to obtain the most specific transitions.

Efficient approach for the comprehensive detection of unknown anabolic steroids and metabolites in human urine by liquid chromatography-electrospray-tandem mass spectrometry.

The detection of new anabolic steroid metabolites and new designer steroids in urine is a challenge in doping analysis. An approach based on precursor ion scanning for the detection of unknown anabolic steroids and metabolites is proposed. The study of the MS/MS spectra of selected anabolic steroids revealed different fragmentation pathways at low and medium collision energy depending on the steroid structure.

Elucidation of urinary metabolites of fluoxymesterone by liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry.

The suitability of liquid chromatography tandem mass spectrometry (LC-MS/MS) and gas chromatography mass spectrometry (GC-MS) for the elucidation of fluoxymesterone metabolism has been evaluated. Electrospray ionization (ESI) and collision induced dissociation (CID) fragmentation in LC-MS/MS and electron impact spectra (EI) in GC-MS have been studied for fluoxymesterone and two commercially available metabolites. MS(n) experiments and accurate mass measurements performed by an ion-trap analyser and a QTOF instrument respectively have been used for the elucidation of the fragmentation pathway.

Development and validation of a qualitative screening method for the detection of exogenous anabolic steroids in urine by liquid chromatography-tandem mass spectrometry.

A screening method for the urinary detection of 34 exogenous anabolic steroids has been developed. The method involves an enzymatic hydrolysis, liquid-liquid extraction and detection by liquid chromatography-tandem mass spectrometry. The use of some adducts such as [M+NH(4)](+), [M+CH(3)COO](-) and [M+H+MeOH](+) was necessary in order to detect some analytes at the required level (lower than 10 ng/ml).

Development of a qualitative liquid chromatography/tandem mass spectrometric method for the detection of narcotics in urine relevant to doping analysis.

A new screening procedure for 18 narcotics in urine for anti-doping purposes has been developed using liquid chromatography/triple quadrupole mass spectrometry (LC/MS). Electrospray ionization (ESI) was used as interface. Infusion experiments were performed for all substances to investigate their mass spectrometric behaviour in terms of selecting product specific ions.

Presence of endogenous interferences in the urinary detection of selected anabolic steroids by liquid chromatography/electrospray tandem mass spectrometry.

The use of liquid chromatography/tandem mass spectrometry (LC/MS/MS) can give several benefits in the urinary detection of anabolic steroids (AS) such as avoiding the derivatization step or the possible direct detection of conjugated AS. However, the presence of endogenous compounds with similar structures can interfere with this detection, thus decreasing the reliability of the method. The circumvention of these interferences by the use of different MS/MS transitions has been studied.

Ionization of anabolic steroids by adduct formation in liquid chromatography electrospray mass spectrometry.

The ionization of 46 anabolic steroids has been studied. The absence of basic or acidic moieties in most of these analytes makes their direct ionization as [M + H]+ by atmospheric pressure interfaces difficult. The formation of adducts with different components of the mobile phase has been found to be an efficient way to ionize anabolic steroids by electrospray.

Metabolism and excretion of anabolic steroids in doping control--new steroids and new insights.

The use of anabolic steroids in sports is prohibited by the World Anti-Doping Agency. Until the 1990s, anabolic steroids were solely manufactured by pharmaceutical companies, albeit sometimes on demand from national sports agencies as part of their doping program. Recently the list of prohibited anabolic steroids in sports has grown due to the addition of numerous steroids that have been introduced on the market by non-pharmaceutical companies.