New internal standard for quantitative determination of oxyphytosterols by gas chromatography

A study was conducted to develop a new internal standard for the quantitative determination of oxyphytosterols. Tests on 5-androsten-3beta,17beta-diol; 5alpha-androstan-3beta,17beta-diol; 5-pregnen-3beta,20alpha-diol; and 5alpha-pregnan-3beta,20beta-diol showed that these compounds were not fully adequate. However, the compound 3beta,22-dihydroxy-20-homo-5-pregnene, synthesized in 4 steps, resulted in a promising internal standard, with a molecule similar to hydroxysterols; retention time as trimethylsilyl in gas chromatography comprised between 5alpha-cholestane and 7alpha-hydroxycholesterol; clear mass spectrum in electronic impact mass spectrometry, with several intense ions suitable for selected ion monitoring-mass spectrometry. Further studies are necessary to observe the behavior of these compounds during the entire analytical procedure.