NEW METHOD OF CALCULATION OF KOVATS RETENTION INDICES FOR SUBSTANCES CHROMATOGRAPHED ON CARBON ADSORBENTS

摘要

Inverse gas chromatography (IGC) is widely used for the investigation of both carbon and non-carbon adsorbents characterizing by a weakly and strongly developed micropore structure and polimers. From the chromatographic data the physico-chemical parameters of adsorption e.g., standard free energy of adsorption, surface energy and entropy of specific interactions are calculated. The suitability of IGC for physico-chemical invesigations follows from the fact, that a chromatographic process is related to the properties and physico-chemical interactions of column filling (e.g. carbon or non-carbon adsorbent) with the chromatographed substances. Reflection of these interactions is the retention of chromatographed substances. One of more important parameter characterizing a substance retention in precisely defined chromatographic system is Kovats retention index. According to carrying out the chromatographic process in this case we most often deal with non-ideal, linear chromatography and rarely with ideal, linear chromatography [5], and ideal, non-linear one . Only in a few articles describing adsorbent investigations one may find mentions about the obtained results at the conditions typical of non-ideal, non-linear chromatographic process. If retention time of adsorbate depends on amount of the adsorbate injected on column, then the retention volume and Kovats retention index also depend on it. In this paper a new method for calculation of net retention volumes and Kovats retention indices calculated on the basis of them is described. The proposed method may be applied in the case when the temperature retention dependency is a continuous function in temperature interval in which the measurements are carried out.