Abstract: A short review is presented on the application of infrared spectroscopy to catalysis with emphasis on the principal stages in the studies of heterogeneous catalytic reactions. Examples are given (mainly from the research activity of Bulgarian scientists) that show the modes, the basic problems and approaches in application of the method to characterisation of reactants, catalysts, adsorption and desorption processes, formation and conversion of intermediates, studies on reaction mechanisms. The review is aimed at revealing that IR spectroscopy, in its 60-year history of application in catalysis, is now probably the most informative, powerful, fruitful, flexible, and convenient method for use in wide range of experimental conditions.

Abstract: The present paper summarizes the definitions of terms: chemical species, speciation analysis, speciation and fractionation. A categorization of chemical species is made according to isotopic composition of the element, its oxidation and electronic states and its complex and molecular structure. The methods used for analysis of different chemical species are briefly discussed. Attention is paid to fractionation and some methodological requirements and approaches. Some dynamic aspects of speciation analysis are concerned as well. The discussed items are in accordance with the guidelines for the subject reported as IUPAC recommendations.