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Steroids. 2006 Jan;71(1):42-53. Epub 2005 Sep 30.

Analysis of derivatised steroids by matrix-assisted laser desorption/ionisation and post-source decay mass spectrometry.

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  • 1Department of Pharmaceutical and Biological Chemistry, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.


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.

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