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.
A description of the methods used to build a high quality, comprehensive reference library of electron-ionization mass spectra is presented. Emphasis is placed on the most challenging part of this project--the improvement of quality by expert evaluation. The methods employed for this task were developed over the course of a spectrum-by-spectrum review of a library containing well over 100,000 spectra. Although the effectiveness of this quality improvement task depended critically on the expertise of the evaluators, a number of guidelines are discussed which were found to be effective in performing this onerous and often subjective task. A number of specific examples of the particularly challenging task of spectrum editing are given.
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.
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