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Updated: Aug 15, 2026

Dithranol as a Matrix for Matrix Assisted Laser Desorption/Ionization Imaging on a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer
Published on: November 26, 2013
Analysis of derivatised steroids by matrix-assisted laser desorption/ionisation and post-source decay mass
Muhammad Atif Khan1, Yuqin Wang, Sibylle Heidelberger
1Department of Pharmaceutical and Biological Chemistry, The School of Pharmacy, University of London, 29-39 Brunswick Square, London WC1N 1AX, UK.
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.
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