The metabolism and urinary excretion of 1,2(n)-3H-1-dehydrotestosterone were studied in cross-bred gelded horses. Approximately 40% of the dose was excreted in 24 h. The steroid metabolites were extracted by Amberlite XAD-2 resin and fractionated into glucuronides and sulphoconjugates. Unchanged 1-dehydrotes-tosterone was the only component identified by gas chromatography mass spectrometry after solvolysis of the sulphoconjugates. Positive and negative ion fast atom bombardment mass spectra were obtained on the purified 1-dehydrotestosterone sulphoconjugate isolated from horse urine and on the alkali metal salts of three standard steroid conjugates. Spectra obtained in the different modes were of comparable intensity. Positive ion spectra were generally more complex due to the formation of alkali metal adduct ions containing several sodium cations. The most abundant ion in the negative ion spectra corresponded to the loss of the alkali metal cation to give [M]−. Thus, the structure of a conjugate can be defined from the combination of mass spectrometric techniques.

Studies related to the metabolism of anabolic steriods in the horse: The metabolism of 1-dehydrotestosterone and the use of fast atom bombardment mass spectrometry in the identification of steroid conjugates

The structures of the sterol side chains and ring systems discussed in this chapter are presented in Figs. 1 and 2 respectively.

GC-MS of Plant Sterol Analysis

Les steroides anabolisants androgenes peu acides ou basiques ne permettent pas d’obtenir des signaux importants lors de leur analyse par spectrometrie de masse electrospray (ESI-MS), rendant ainsi leur detection compliquee par l’utilisation de cette technique. Bien que certains steroides puissent etre analyses de maniere adequate avec des methodes d’analyse antidopage classiques comme la chromatographie en phase gazeuse (GC) couplee a la MS avec une source d’ionisation electronique (EI), il reste un besoin pour le developpement d’une methode qui soit capable de detecter efficacement les composes plus difficiles, c’est-a-dire ceux qui sont moins susceptibles de s’ioniser en ESI. Pour resoudre ce probleme l’approche envisagee se base sur l’addition d’anions (sous forme de sel d’ammonium) a des steroides anabolisants comme principe pour le developpement d’une methode analytique de detection de ces composes. Il a ete confirme que les limites de detection instrumentales obtenues avec ces anions sont plus basses qu’en comparaison des memes analyses sans additif en ESI positif ou negatif. Les etapes de developpement de cette methode basee sur la chromatographie en phase liquide (LC) couplee a la MS en tandem sont egalement presentees. Les resultats obtenus sur des echantillons en matrice urinaire demontrent que l’attachement anionique apporte une nouvelle approche prometteuse pour la detection des steroides en controle antidopage. De plus, des experiences sur des steroides bifonctionnels comme la 5-α-pregnan-3α,20β-diol ou la d4-17,21,21,21-pregnenolone reduite ont permis de mieux apprehender les facteurs qui permettent que l’attachement preferentiel d’un anion donne puisse se faire sur une region specifique de la molecule, i.e. que l’attachement anionique soit « regioselectif ». La fragmentation des adduits anioniques de steroides bifonctionnels en MS en tandem a montre des voies de decomposition produisant des ions produits caracteristiques de chaque anion. La determination d’acidites en phase gazeuse obtenues par des calculs de chimie theorique a egalement permis d’apporter une nouvelle lumiere sur le comportement des adduits anion-steroide.

/pdf/attachement-anionique-en-spectrometrie-de-masse-electrospray-3oe62m2aan.pdf

Attachement anionique en spectrométrie de masse électrospray négative : étude de la régiosélectivité et application à l'amélioration de la détection des stéroïdes en matrice urinaire pour le contrôle antidopage dans le sport.

CHAPTER 7 – Derivatization and Gas Chromatography in the Mass Spectrometry of Steroids

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CHAPTER 7 – Derivatization and Gas Chromatography in the Mass Spectrometry of Steroids