The determination of steroids with and without natural electrophores by gas chromatography and electron‐capture detection

Abstract

The response of the electron-capture detector to organic compounds is poorly defined, and the steroids are no exception to this observation. For those steroids which are naturally electron-capturing, the structures of the electrophores will be defined. Other steroids can be made electron-capturing by the formation of appropriate derivatives. Some new or infrequently used reagents for this purpose (flophemesyl ethers, t-bulflophemesyl ethers, pentafluorophenylhydrazone derivatives and halogen-substituted aromatic boronic acids) are described.

Determination of testosterone:epitestosterone ratio after pentafluorophenyldimethylsilyl-trimethylsilyl derivatisation using gas chromatography-mass spectrometry in equine urine

“…The pentafluorophenyldimethylsilyl (abbreviated to flophemesyl for convenience) derivatives generally show a strong molecular ion and provide much more detailed diagnostic information. 9,10 The objective of this work was to improve the determination of testosterone : epitestosterone ratios in equine urine by using a novel mixed flophemesyl-trimethylsilyl ether derivatisation method. The new method was assessed by GC-MS analyses and comparisons with deuterium labelled testosterone and epitestosterone internal standards were made.…”

Bringing GC–MS profiling of steroids into clinical applications

“…In general, alkyl or aryl compounds with closely bound fluorine atoms are remarkable in that they show little increase in boiling point compared to hydrocarbons containing a similar number of carbon atoms. However, the flophemesyl ring is a strong electron‐attracting group that is able to influence the mode of fragmentation of steroid derivatives under electron impact in a way that leads to diagnostic mass spectra (Poole et al, ; Jayasinghe et al, ). Flophemesyl chloride does not cause the formation of enol ethers or react with hindered steroid hydroxyl groups, but rapidly reacts with unhindered secondary hydroxyl groups to produce silyl ethers (Morgan & Poole, ).…”

Sample Preparation for Chromatographic Analysis

“…To improve the detectability of silyl ethers, silylation reagents containing an electron-capturing group [443,[449][450][451]468] or cyano group for thermionic detection [469] have been prepared. The 2-cyanoethyldimethylsilyl derivatives are only marginally more sensitive (ca.…”

“…However, it may be desirable to protect ketone groups when other functional groups are derivatized to avoid enolization or condensation reactions that might result in byproduct formation. This derivative is generally superior to the 2,4dinitrophenylhydrazone and pentafluorophenylhydrazone derivatives which do not s t o r e well and f r e q u e n t l y produce byproducts [468,515,516]. The most common reagents used are methylhdyroxylamine, ethylhydroxylamine and benzylhydroxylamine as their hydrochloride salts.…”