Chemical Derivatization for Liquid Chromatography and Mass Spectrometry of Nucleosides and their Analogs

Abstract

<p>Currently, nucleosides and their analogs are routinely analysed by reverse phase (RP) or ion exchange (IEX) high performance liquid chromatography (HPLC) with UV detection. These methods require the use of buffer solutions which are incompatible with the newly introduced method of combined liquid chromatography-mass spectrometry (LC-MS). The LC-MS interface is not capable of eliminating the involatile salts in the buffers. Accumulation of these salts would cause arcing in the ion source. In addition, the nucleosides are polar and their analysis by this method, without chemical modification, would lead to the mass spectra of pyrolysis products. In this thesis a method involving chemical derivatization and combined LC-MS of the nucleosides and their analogs in discussed.</p> <p>N, N'-methylene-bridged dinucleosides were derivatized with tert-butyl-dimethylsilyl (TBDMS) reagent, purified and analysed by liquid chromatography and combined LC-MS. Mixed derivatization of the nucleosides to produce the N-dimethylaminomethylene-O-tertbutyldimethylsilyl (DMAM-TBDMS) derivatives and optimization of conditions are examined. The liquid chromatographic and combined LC-MS analyses of these derivatives are discussed. The electron-impact mass spectral fragmentation and rearrangement mechanisms of the TBDMS derivatives of the dinucleosides and the DMAM-TBDMS derivatives of the nucleosides are discussed.</p>