Structure and mechanism of formation of an important ion in doping control

Chad R. Borges, James Taccogno, Dennis J. Crouch, Ly Le, Thanh N. Truong

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


An ion with m/z 143 serves as a biomarker that is often continuously monitored in urine samples undergoing screening by electron ionization gas chromatography/mass spectrometry (EI GC/MS) for banned anabolic agents. The ion is known to arise from trimethylsilyl (TMS)-derivatized synthetic 17-hydroxy, 17-methyl steroids. The purpose of this work was to characterize, in detail, the origin(s), structure(s), and mechanism(s) of formation of such ions with m/z 143. High resolution mass spectrometry (HRMS) data revealed the elemental composition of the D-ring derived m/z 143 ion to be C7H 15OSi. Analysis of dihydrotestosterone (DHT) and its 2-methyl substituted analog dromostanolone by HRMS revealed that an elementally equivalent ion of m/z 143 could be derived from the A-ring of TMS-derivatized 3-keto-enol steroids demonstrating that an abnormally intense peak in the m/z 143 extracted ion chromatogram of urine samples undergoing screening for banned anabolic agents does not necessarily indicate the presence of a 17-hydroxy, 17-methyl steroid. To gain information on ion structure, breakdown curves for the most abundant product ions of the m/z 143 ion were generated using both native and perdeutero-TMS derivatives, providing structures for second, third, and fourth generation product ions. An EI-mass spectrum of [16,16,17- 2H3]-DHT (DHT-d3) demonstrated that one of the C-16 hydrogen atoms is removed prior to the formation of an ion that is highly analogous to the ion with m/z 143 strongly suggesting, in accord with all other evidence, one particular fragmentation pathway and resulting product: a resonance stabilized 3-(O-trimethylsilyl)but-1-ene ion.

Original languageEnglish (US)
Pages (from-to)48-54
Number of pages7
JournalInternational Journal of Mass Spectrometry
Issue number1-3
StatePublished - Dec 1 2005
Externally publishedYes


  • Anti-doping
  • Ion structure
  • Steroids
  • m/z 143

ASJC Scopus subject areas

  • Instrumentation
  • Condensed Matter Physics
  • Spectroscopy
  • Physical and Theoretical Chemistry


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