ESI mass spectrometry of amino acid trimethylsilylethyl esters

The fragmentation mechanism of β-(N-alkyl/arylamino)-α,β-unsaturated carboxylates under electrospray ionization conditions

The positive ion mass spectrometric behavior of six beta-(N-alkyl/arylamino)-alpha,beta-unsaturated carboxylates, alpha-(1-alkyl/arylaminoethylidene)-gamma-lactones, has been studied under electrospray ionization conditions. Their fragmentation pathways are described and supported by tandem mass spectrometry. The protonated compounds are apt to eliminate a water, and a water plus a oxacyclopent-2-yne molecule. Some of the compounds show a tendency to undergo a four-membered ring contraction rearrangement to lose a carbon dioxide. The fragmentation patterns of these compounds exhibit a strong substituent dependency.

Derivatization in mass spectrometry--8. Soft ionization mass spectrometry of small molecules

This is the first of two reviews devoted to derivatization approaches for "soft" ionization mass spectrometry (FAB, MALDI, ESI, APCI) and deals, in particular, with small molecules. The principles of the main "soft" ionization mass spectrometric methods as well as the reasons for derivatizing small molecules are briefly described. Derivatization methods for modification of amines, carboxylic acids, amino acids, alcohols, carbonyl compounds, monosaccharides, thiols, unsaturated and aromatic compounds etc. to improve their ionizability and to enhance structure information content are discussed. The use of "fixed"-charge bearing derivatization reagents is especially emphasized. Chemical aspects of derivatization and "soft" ionization mass spectrometric properties of derivatives are considered.

Derivatization in mass spectrometry--1. Silylation

This is the first of a series of reviews on the application of derivatization in mass spectrometry. A description is given of advances in silylation as a powerful tool used for increasing the volatility, thermal and thermo-catalytic stability, and chromatographic mobility of polar and unstable organic compounds. In addition to chemical aspects of silylation, mass spectral properties of silyl derivatives useful for structure determination and quantitation of various organic and biologically-active compounds, mainly by GC/MS, are described. Practically all tested and widely used silylating agents are described. The role of comprehensive libraries containing reference mass spectra for various silyl derivatives and search systems in structure determination is emphasized. Applications of silylation for particular analyses are summarised.