[show abstract][hide abstract] ABSTRACT: Two-step derivatization procedures were developed for the enhancement of the positive ESI in LC-MS detection of anabolic androgenic steroids, a class of prohibited substances with limited ionization efficiency in atmospheric pressure interfaces. The developed procedures are based on the esterification of hydroxyl groups of anabolic steroids with picolinic acid, followed by conversion of carbonyl groups to Schiff bases by either Girard's reagent T or 2-hydrazino pyridin.
Ionization efficiency for the model derivatized compounds 19-norandrosterone (nandrolone main metabolite) and methasterone was higher by almost two orders of magnitude compared with the respective efficiency of the underivatized compounds.
The obtained derivatives provided a significant improvement in the ESI sensitivity, compared with those of underivatized molecules in positive LC-ESI-ion trap-MS full-scan mode.
[show abstract][hide abstract] ABSTRACT: Unification of the screening protocols for a wide range of doping agents has become an important issue for doping control laboratories. This study presents the development and validation of a generic liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS) screening method of 241 small molecule analytes from various categories of prohibited substances (stimulants, narcotics, diuretics, beta(2)-agonists, beta-blockers, hormone antagonists and modulators, glucocorticosteroids and anabolic agents). It is based on a single-step liquid-liquid extraction of hydrolyzed urine and the use of a rapid-resolution liquid chromatography/high-resolution time-of-flight mass spectrometric system acquiring continuous full scan data. Electrospray ionization in the positive mode was used. Validation parameters consisted of identification capability, limit of detection, specificity, ion suppression, extraction recovery, repeatability and mass accuracy. Detection criteria were established on the basis of retention time reproducibility and mass accuracy. The suitability of the methodology for doping control was demonstrated with positive urine samples. The preventive role of the method was proved by the case where full scan acquisition with accurate mass measurement allowed the retrospective reprocessing of acquired data from past doping control samples for the detection of a designer drug, the stimulant 4-methyl-2-hexanamine, which resulted in re-reporting a number of stored samples as positives for this particular substance, when, initially, they had been reported as negatives.
Rapid Communications in Mass Spectrometry 06/2010; 24(11):1595-609. · 2.51 Impact Factor
[show abstract][hide abstract] ABSTRACT: A common trend in food contaminants and sports doping control is towards a limited number of targeted, full-scan, accurate-mass spectrometry (MS) methods based on time-of-flight (TOF) or Fourier-transform orbital trap (Orbitrap) mass analyzers. Retrospective analysis of the full-scan datasets of signals from emerging contaminants, novel metabolites and illegal designer substances is a major step forward. We present data from recent applications of gas chromatography with TOF-MS, ultra-high-performance liquid chromatography (LC) with TOF-MS and LC-Orbitrap MS in the screening of European Commission-regulated veterinary drugs and other contaminants in foods, and World Anti-Doping Agency-prohibited substances. We discuss the potential impact of these new approaches on future developments.
TrAC : Trends in Analytical Chemistry 29 (2010) 11. 01/2010;
[show abstract][hide abstract] ABSTRACT: While a number of different derivatization procedures for screening GC-MS analysis of prohibited substances are followed by doping control laboratories, a unified derivatization procedure for the GC-MS analysis of 190 different doping agents was developed.
Following preliminary experiments, a two-step derivatization procedure was selected. The evaluation of various silylation parameters, such as reagent composition, reaction time, reaction temperature, catalysts and microwave oven reaction time, for this procedure was carried out.
The suitability of the developed procedure was demonstrated through application on urine samples at concentration levels of the minimum required performance limit for all tested substances. This new derivatization procedure, which significantly decreases time and cost, is suitable for a routine basis application.
[show abstract][hide abstract] ABSTRACT: In equine sport, salicylic acid is prohibited with a threshold level of 750 microg mL(-1) in urine; hence, doping control laboratories have to establish quantitative and qualitative methods for its determination. A simple and rapid liquid chromatographic/mass spectrometric method was developed and validated for the quantification and identification of salicylic acid. Urine samples after 900-fold dilution and addition of the internal standard (4-methylsalicylic acid) were directly injected to the liquid chromatography/quadrupole time-of-flight mass spectrometry system. Electrospray ionization in negative mode with full scan acquisition mode and product ion scan mode were chosen for the quantification and identification of salicylic acid, respectively. Run time was 2.0 min. The tested linear range was 2.5-50 microg mL(-1) (after 100-fold sample dilution). The relative standard deviations of intra- and inter-assay analysis of salicylic acid in horse urine were lower than 2.5% and 2.8%, respectively. Overall accuracy (relative percentage error) was less than 3.3%. Method was applied to two real samples found to be positive for salicylic acid, demonstrating simplicity, accuracy, and selectivity.
Analytical and Bioanalytical Chemistry 09/2009; 395(5):1403-10. · 3.66 Impact Factor
[show abstract][hide abstract] ABSTRACT: Levodopa and dopamine have been abused as performance-altering substances in horse racing. Urinary 3-methoxytyramine is used as an indicator of dopaminergic manipulation resulting from dopamine or levodopa administration and is prohibited with a urinary threshold of 4 microg mL(-1) (free and conjugated). A simple liquid chromatographic (LC)/mass spectrometric (MS) (LCMS) method was developed and validated for the quantification and identification of 3-methoxytyramine in equine urine. Sample preparation involved enzymatic hydrolysis and protein precipitation. Hydrophilic interaction liquid chromatography (HILIC) was selected as a separation technique that allows effective retention of polar substances like 3-methoxytyramine and efficient separation from matrix compounds. Electrospray ionization (ESI) in positive mode with product ion scan mode was chosen for the detection of the analytes. Quantification of 3-methoxytyramine was performed with fragmentation at low collision energy, resulting in one product ion, while a second run at high collision energy was performed for confirmation (at least three abundant ions). Studies on matrix effects showed ion suppression depending on the horse urine used. To overcome the variability of the results originating from the matrix effects, isotopic labelled internal standard was used and linear regression calibration methodology was applied for the quantitative determination of the analyte. The tested linear range was 1-20 microg mL(-1). The relative standard deviations of intra- and inter- assay analysis of 3-methoxytyramine in horse urine were lower than 4.2% and 3.2%, respectively. Overall accuracy (relative percentage error) was less than 6.2%. The method was applied to case samples, demonstrating simplicity, accuracy and selectivity.
Drug Testing and Analysis 08/2009; 1(8):365-71. · 3.17 Impact Factor
[show abstract][hide abstract] ABSTRACT: In equine sport, theobromine is prohibited with a threshold level of 2 microg mL(-1) in urine, hence doping control laboratories have to establish quantitative and qualitative methods for its determination. Two simple liquid chromatography/mass spectrometry (LC/MS) methods for the identification and quantification of theobromine were developed and validated using the same sample preparation procedure but different mass spectrometric systems: ion trap mass spectrometry (ITMS) and time-of-flight mass spectrometry (TOFMS). Particle-free diluted urine samples were directly injected into the LC/MS systems, avoiding the time-consuming extraction step. 3-Propylxanthine was used as the internal standard. The tested linear range was 0.75-15 microg mL(-1). Matrix effects were evaluated analyzing calibration curves in water and different fortified horse urine samples. A great variation in the signal of theobromine and the internal standard was observed in different matrices. To overcome matrix effects, a standard additions calibration method was applied. The relative standard deviations of intra- and inter-day analysis were lower than 8.6 and 7.2%, respectively, for the LC/ITMS method and lower than 5.7 and 5.8%, respectively, for the LC/TOFMS method. The bias was less than 8.7% for both methods. The methods were applied to two case samples, demonstrating simplicity, accuracy and selectivity.
Rapid Communications in Mass Spectrometry 04/2009; 23(7):1020-8. · 2.51 Impact Factor
[show abstract][hide abstract] ABSTRACT: Two simple and rapid LC/MS methods with direct injection analysis were developed and validated for the quantification and identification of hydrocortisone in equine urine using the same sample preparation but different mass spectrometric systems: ion trap mass spectrometry (IT-MS) and time-of-flight mass spectrometry (TOF-MS). The main advantage of the proposed methodology is the minimal sample preparation procedure, as particle-free diluted urine samples were directly injected into both LC/MS systems. Desonide was used as internal standard (IS). The linear range was 0.25-2.5 microg ml(-1) for both methods. Matrix effects were evaluated by preparing and analyzing calibration curves in water solutions and different horse urine samples. A great variation of the signal both for hydrocortisone and the internal standard was observed in different matrices. To overcome matrix effects, the unavailability of blank matrix and the excessive cost of the isotopically labeled internal standard, standard additions calibration method was applied. This work is an exploration of the performance of the standard additions approach in a method where neither nonisotopic internal standards nor extensive sample preparation is utilized and no blank matrix is available. The relative standard deviations of intra and interday analysis of hydrocortisone in horse urine were lower than 10.2 and 5.4%, respectively, for the LC/IT-MS method and lower than 8.4 and 4.4%, respectively, for the LC/TOF-MS method. Accuracy (bias percentage) was less than 9.7% for both methods.
Journal of Mass Spectrometry 05/2008; 43(9):1255-64. · 3.21 Impact Factor
[show abstract][hide abstract] ABSTRACT: A new combined doping control screening method for the analysis of anabolic steroids in human urine using liquid chromatography/electrospray ionization orthogonal acceleration time-of-flight mass spectrometry (LCoaTOFMS) and gas chromatography/electron ionization orthogonal acceleration time-of-flight mass spectrometry (GCoaTOFMS) has been developed in order to acquire accurate full scan MS data to be used to detect designer steroids. The developed method allowed the detection of representative prohibited substances, in addition to steroids, at concentrations of 10 ng/mL for anabolic agents and metabolites, 30 ng/mL for corticosteroids, 500 ng/mL for stimulants and beta-blockers, 250 ng/mL for diuretics, and 200 ng/mL for narcotics. Sample preparation was based on liquid-liquid extraction of hydrolyzed human urine, and the final extract was analyzed as trimethylsilylated derivatives in GCoaTOFMS and underivatized in LCoaTOFMS in positive ion mode. The sensitivity, mass accuracy, advantages and limitations of the developed method are presented.
Rapid Communications in Mass Spectrometry 02/2007; 21(15):2439-46. · 2.51 Impact Factor
[show abstract][hide abstract] ABSTRACT: This study summarizes the results obtained from the doping control analysis during the period of the XXVIII summer Olympic Games (30 July–29 August 2004). The analysis of all doping control samples was performed at the Doping Control Laboratory (DCL)—the World Anti-Doping Agency (WADA) Accredited Laboratory of Athens. Three thousand six hundred and seventeen tests were conducted in total throughout the games. In 23 specimens the presence of a prohibited substance was confirmed. Sixteen of those were related to anabolic agents. The screened results were confirmed with various mass spectrometry analytical techniques, such as gas chromatography/high resolution mass spectrometry (GC/HRMS), gas chromatography/mass spectrometry (GC/MS), gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) and liquid chromatography/mass spectrometry (ion trap) (LC/MS). The results of the first time applied screening and confirmatory procedures for the detection of recombinant human growth hormone in serum were also presented. Besides, 107 therapeutic use exemptions (TUE) were verified for glucocorticosteroid and beta2-agonist use.
[show abstract][hide abstract] ABSTRACT: A study of the metabolism of isometheptene, an antispasmodic drug, in man and comparison with heptaminol metabolism, is presented in this paper. Isometheptene and two metabolites were detected in human urine after oral administration of a tablet containing isometheptene mucate. The urine level of the parent drug, which is excreted during the first 24 h, was determined using gas chromatography-mass spectrometry, after alkaline extraction with organic solvent. A minor metabolite of isometheptene was converted to heptaminol in vitro under the acidic hydrolysis conditions used for the screening procedure of stimulants and narcotics in doping control analysis.
Journal of Chromatography B 01/2006; 827(2):199-204. · 2.49 Impact Factor
[show abstract][hide abstract] ABSTRACT: Xylazine and its main metabolites were detected in equine urine after a single-dose intravenous administration of 0.98 and 1.01 mg/kg body weight xylazine, respectively, in two horses, in order to be used for equine doping control routine analysis. The urine levels of the parent drug and its metabolites were determined using gas chromatography-mass spectrometry (GC-MS). Xylazine is metabolised rapidly, down to a concentration level of about 1.0 microg/ml after 1-3h administration. Seven metabolites were identified in urine. 4-Hydroxy-xylazine, the major metabolite, could be traced for 25 h and it is regarded as the long-term metabolite of xylazine in horse. 2,6-Dimethylaniline was, for the first time, reported as metabolite in equine.
Journal of Pharmaceutical and Biomedical Analysis 05/2004; 35(1):107-16. · 2.95 Impact Factor