title: Analysis of derivatised steroids by matrix-assisted laser desorption/ionisation and post-source decay mass spectrometry.
abstract: Neutral steroids are difficult to analyse using desorption ionisation methods coupled with mass spectrometry (MS). However, steroids with an unhindered ketone group can readily be derivatised with the Girard P (GP) reagent to give GP hydrazones. Steroid GP hydrazones contain a quaternary nitrogen atom and are readily desorbed in the matrix-assisted laser desorption/ionisation (MALDI) process, giving an improvement in sensitivity of two orders of magnitude. Steroids without a ketone group, but with a 3beta-hydroxy-Delta5 function, can be readily converted to 3-oxo-Delta4 steroids and subsequently derivatised to GP hydrazones for MALDI analysis. In addition to giving strong [M]+ ions upon MALDI, steroid GP hydrazones give informative post-source decay (PSD) spectra. By using the accurate mass of the precursor-ion measured by MALDI-MS, in combination with the structural information encoded in its PSD spectrum, steroid structures can readily be determined.
authors.affiliation: Department of Pharmaceutical and Biological Chemistry, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.
authors.forename: Muhammad Atif
authors.initials: MA
authors.lastname: Khan
authors.forename: Yuqin
authors.initials: Y
authors.lastname: Wang
authors.forename: Sibylle
authors.initials: S
authors.lastname: Heidelberger
authors.forename: Gunvor
authors.initials: G
authors.lastname: Alvelius
authors.forename: Suya
authors.initials: S
authors.lastname: Liu
authors.forename: Jan
authors.initials: J
authors.lastname: Sjövall
authors.forename: William J
authors.initials: WJ
authors.lastname: Griffiths
mesh_terms: D006835:Hydrazones / Q000737:chemistry*; D013058:Mass Spectrometry; D015394:Molecular Structure; D011280:Pregnanolone / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013256:Steroids / Q000032:analysis*; D013739:Testosterone / Q000737:chemistry*
chemical_list: D006835:Hydrazones; D013256:Steroids; D013739:Testosterone; D011280:Pregnanolone