The Experts below are selected from a list of 87 Experts worldwide ranked by ideXlab platform

F T Delbeke - One of the best experts on this subject based on the ideXlab platform.

  • elucidation of urinary metabolites of Fluoxymesterone by liquid chromatography tandem mass spectrometry and gas chromatography mass spectrometry
    Journal of Mass Spectrometry, 2008
    Co-Authors: Oscar J Pozo, Wim Van Thuyne, Koen Deventer, Peter Van Eenoo, F T Delbeke
    Abstract:

    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. The neutral loss scan of 20 Da (loss of HF) in LC-MS/MS has been applied for the selective detection of Fluoxymesterone metabolites. In a positive Fluoxymesterone doping control sample, 9 different analytes have been detected including the parent compound. Seven of these metabolites were also confirmed by GC-MS including 5 previously unreported metabolites. On the basis of the ionization, the CID fragmentation, the accurate mass of the product ions and the EI spectra of these analytes, a tentative elucidation as well as a proposal for the metabolic pathway of Fluoxymesterone has been suggested. The presence of these compounds has also been confirmed by the analysis of five other positive Fluoxymesterone urine samples.

  • efficient approach for the comprehensive detection of unknown anabolic steroids and metabolites in human urine by liquid chromatography electrospray tandem mass spectrometry
    Analytical Chemistry, 2008
    Co-Authors: Oscar J Pozo, Koen Deventer, Peter Van Eenoo, F T Delbeke
    Abstract:

    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. However, after analysis at high collision energy three common ions at m/z 105, m/z 91, and m/z 77 were found for all studied anabolic steroids. These ions can be explained by the fragmentation of the steroid structure and corresponded to the methyl tropylium, tropylium, and phenyl ions, respectively. Because of the theoretical low specificity of these ions, the simultaneous presence of all of them was used as a starting point to consider a substance as a possible anabolic steroid. Hence, the developed approach is based on the simultaneous acquisition of the precursor ion scan of m/z 105, 91, and 77. The specificity of this approach has been checked by the injection of several doping agents including beta-agonists, corticosteroids, beta-blockers, and diuretics. In general, only compounds with a steroidal structure showed a signal at all three selected m/z values although some exceptions have been found. The applicability of the method was tested for three different scenarios: the detection of steroid metabolites, the detection of unknown steroids, and the analysis of prohormones. In metabolic studies, several recently reported Fluoxymesterone metabolites were also found using this method. For detection of unknown steroids, some negative urine samples were spiked with the designer steroid THG and 33 other anabolic steroids and treated as blind samples. Finally, the applicability of the developed approach for the analysis of dietary supplements was checked by the analysis of a prohormone where several impurities and/or degradation products were found.

Oscar J Pozo - One of the best experts on this subject based on the ideXlab platform.

  • elucidation of urinary metabolites of Fluoxymesterone by liquid chromatography tandem mass spectrometry and gas chromatography mass spectrometry
    Journal of Mass Spectrometry, 2008
    Co-Authors: Oscar J Pozo, Wim Van Thuyne, Koen Deventer, Peter Van Eenoo, F T Delbeke
    Abstract:

    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. The neutral loss scan of 20 Da (loss of HF) in LC-MS/MS has been applied for the selective detection of Fluoxymesterone metabolites. In a positive Fluoxymesterone doping control sample, 9 different analytes have been detected including the parent compound. Seven of these metabolites were also confirmed by GC-MS including 5 previously unreported metabolites. On the basis of the ionization, the CID fragmentation, the accurate mass of the product ions and the EI spectra of these analytes, a tentative elucidation as well as a proposal for the metabolic pathway of Fluoxymesterone has been suggested. The presence of these compounds has also been confirmed by the analysis of five other positive Fluoxymesterone urine samples.

  • efficient approach for the comprehensive detection of unknown anabolic steroids and metabolites in human urine by liquid chromatography electrospray tandem mass spectrometry
    Analytical Chemistry, 2008
    Co-Authors: Oscar J Pozo, Koen Deventer, Peter Van Eenoo, F T Delbeke
    Abstract:

    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. However, after analysis at high collision energy three common ions at m/z 105, m/z 91, and m/z 77 were found for all studied anabolic steroids. These ions can be explained by the fragmentation of the steroid structure and corresponded to the methyl tropylium, tropylium, and phenyl ions, respectively. Because of the theoretical low specificity of these ions, the simultaneous presence of all of them was used as a starting point to consider a substance as a possible anabolic steroid. Hence, the developed approach is based on the simultaneous acquisition of the precursor ion scan of m/z 105, 91, and 77. The specificity of this approach has been checked by the injection of several doping agents including beta-agonists, corticosteroids, beta-blockers, and diuretics. In general, only compounds with a steroidal structure showed a signal at all three selected m/z values although some exceptions have been found. The applicability of the method was tested for three different scenarios: the detection of steroid metabolites, the detection of unknown steroids, and the analysis of prohormones. In metabolic studies, several recently reported Fluoxymesterone metabolites were also found using this method. For detection of unknown steroids, some negative urine samples were spiked with the designer steroid THG and 33 other anabolic steroids and treated as blind samples. Finally, the applicability of the developed approach for the analysis of dietary supplements was checked by the analysis of a prohormone where several impurities and/or degradation products were found.

Peter Van Eenoo - One of the best experts on this subject based on the ideXlab platform.

  • elucidation of urinary metabolites of Fluoxymesterone by liquid chromatography tandem mass spectrometry and gas chromatography mass spectrometry
    Journal of Mass Spectrometry, 2008
    Co-Authors: Oscar J Pozo, Wim Van Thuyne, Koen Deventer, Peter Van Eenoo, F T Delbeke
    Abstract:

    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. The neutral loss scan of 20 Da (loss of HF) in LC-MS/MS has been applied for the selective detection of Fluoxymesterone metabolites. In a positive Fluoxymesterone doping control sample, 9 different analytes have been detected including the parent compound. Seven of these metabolites were also confirmed by GC-MS including 5 previously unreported metabolites. On the basis of the ionization, the CID fragmentation, the accurate mass of the product ions and the EI spectra of these analytes, a tentative elucidation as well as a proposal for the metabolic pathway of Fluoxymesterone has been suggested. The presence of these compounds has also been confirmed by the analysis of five other positive Fluoxymesterone urine samples.

  • efficient approach for the comprehensive detection of unknown anabolic steroids and metabolites in human urine by liquid chromatography electrospray tandem mass spectrometry
    Analytical Chemistry, 2008
    Co-Authors: Oscar J Pozo, Koen Deventer, Peter Van Eenoo, F T Delbeke
    Abstract:

    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. However, after analysis at high collision energy three common ions at m/z 105, m/z 91, and m/z 77 were found for all studied anabolic steroids. These ions can be explained by the fragmentation of the steroid structure and corresponded to the methyl tropylium, tropylium, and phenyl ions, respectively. Because of the theoretical low specificity of these ions, the simultaneous presence of all of them was used as a starting point to consider a substance as a possible anabolic steroid. Hence, the developed approach is based on the simultaneous acquisition of the precursor ion scan of m/z 105, 91, and 77. The specificity of this approach has been checked by the injection of several doping agents including beta-agonists, corticosteroids, beta-blockers, and diuretics. In general, only compounds with a steroidal structure showed a signal at all three selected m/z values although some exceptions have been found. The applicability of the method was tested for three different scenarios: the detection of steroid metabolites, the detection of unknown steroids, and the analysis of prohormones. In metabolic studies, several recently reported Fluoxymesterone metabolites were also found using this method. For detection of unknown steroids, some negative urine samples were spiked with the designer steroid THG and 33 other anabolic steroids and treated as blind samples. Finally, the applicability of the developed approach for the analysis of dietary supplements was checked by the analysis of a prohormone where several impurities and/or degradation products were found.

Koen Deventer - One of the best experts on this subject based on the ideXlab platform.

  • elucidation of urinary metabolites of Fluoxymesterone by liquid chromatography tandem mass spectrometry and gas chromatography mass spectrometry
    Journal of Mass Spectrometry, 2008
    Co-Authors: Oscar J Pozo, Wim Van Thuyne, Koen Deventer, Peter Van Eenoo, F T Delbeke
    Abstract:

    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. The neutral loss scan of 20 Da (loss of HF) in LC-MS/MS has been applied for the selective detection of Fluoxymesterone metabolites. In a positive Fluoxymesterone doping control sample, 9 different analytes have been detected including the parent compound. Seven of these metabolites were also confirmed by GC-MS including 5 previously unreported metabolites. On the basis of the ionization, the CID fragmentation, the accurate mass of the product ions and the EI spectra of these analytes, a tentative elucidation as well as a proposal for the metabolic pathway of Fluoxymesterone has been suggested. The presence of these compounds has also been confirmed by the analysis of five other positive Fluoxymesterone urine samples.

  • efficient approach for the comprehensive detection of unknown anabolic steroids and metabolites in human urine by liquid chromatography electrospray tandem mass spectrometry
    Analytical Chemistry, 2008
    Co-Authors: Oscar J Pozo, Koen Deventer, Peter Van Eenoo, F T Delbeke
    Abstract:

    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. However, after analysis at high collision energy three common ions at m/z 105, m/z 91, and m/z 77 were found for all studied anabolic steroids. These ions can be explained by the fragmentation of the steroid structure and corresponded to the methyl tropylium, tropylium, and phenyl ions, respectively. Because of the theoretical low specificity of these ions, the simultaneous presence of all of them was used as a starting point to consider a substance as a possible anabolic steroid. Hence, the developed approach is based on the simultaneous acquisition of the precursor ion scan of m/z 105, 91, and 77. The specificity of this approach has been checked by the injection of several doping agents including beta-agonists, corticosteroids, beta-blockers, and diuretics. In general, only compounds with a steroidal structure showed a signal at all three selected m/z values although some exceptions have been found. The applicability of the method was tested for three different scenarios: the detection of steroid metabolites, the detection of unknown steroids, and the analysis of prohormones. In metabolic studies, several recently reported Fluoxymesterone metabolites were also found using this method. For detection of unknown steroids, some negative urine samples were spiked with the designer steroid THG and 33 other anabolic steroids and treated as blind samples. Finally, the applicability of the developed approach for the analysis of dietary supplements was checked by the analysis of a prohormone where several impurities and/or degradation products were found.

Hong Yuan - One of the best experts on this subject based on the ideXlab platform.

  • mass spectrometric identification and characterization of new Fluoxymesterone metabolites in human urine by liquid chromatography time of flight tandem mass spectrometry
    Steroids, 2012
    Co-Authors: Xiaobing Wang, Ying Dong, Xin Liu, Jian Zhao, Hong Yuan
    Abstract:

    Abstract In this study Fluoxymesterone urinary profiles were investigated by liquid chromatography quadrupole time-of-flight tandem mass spectrometry (LC–QTOFMS) with accurate mass measurement. Twelve metabolites including the parent drug were detected in two Fluoxymesterone positive control urine samples. Three parameters were employed for evaluation of the accuracy of the chemical formulae in positive full scan experiment, which contained error between actual and calculated mass weights of prontonated and isotopic molecules together with abundance match between prontonated and isotopic molecules. The 13 analytes were determined with mass accuracy less than 1.1 ppm and isotopic abundance match more than 94 marks. Based on the ionization, CID fragmentation, the accurate mass of the product ion and comparison of the accurate mass weight and retention time with reference standard, Fluoxymesterone and its 12 metabolites containing three unreported ones were detected. The chemical structures of three unreported metabolites were identified as: 9-fluro-17β-ol-17-methyl-11-en-5α-androstan-3-one (F13), 9-fluro-17β-ol-17-methyl-11-en-5β-androstan-3-one (F8) and 9-fluro-17β-ol-17-methyl-5-androstan-3,6,11-trione, and meanwhile a dihydroxylated metabolite (F12), 6,16-dihydroxylated Fluoxymesterone, was also detected in human urine, which was previously reported to be available only in equine urine.