ИСТИНА

Liquid column chromatography is one of the most effective methods for the separation of complex mixtures of various compounds. The resolution of any chromatographic column depends on its efficiency and selectivity of the stationary phase. As a rule, the selectivity of chromatographic separation is defined by the thermodynamics of various interactions between sorbate and the surface of the stationary phase. The interactions between the stationary phase and the solvent of the mobile phase contribute also to the thermodynamics of sorbate-sorbent interactions. A growing interest in the use of kinetic effects to achieve a new separation selectivity has been noted in the last decade. The kinetically selective separations are well known for the preconcentration and separation of isomeric hydrocarbons, hydrogen isotopes, and other kinetic separations in gas-phase systems. An extremely high separation selectivity cab be achieved owing to the difference in the rate of diffusion of gases into highly ordered nanoporous adsorbent. For example, the kinetic selectivity of the separation of propane and propylene, measured as the ratio of the diffusion coefficients of these gases in the solid stationary phase, was a record 1565 [1], which is much higher than the selectivity of the separation of these compounds based on differences in the thermodynamics of interactions with the stationary phase. Much less information has been published regarding the use of kinetic effects for the improvement of the separation selectivity in HPLC. The reported results are contradictory and not always correctly explained. One of the possible reasons for the low number of publications is a lack of adsorbents that can provide a required difference in the diffusion rates of low molecular weight substances. Nevertheless, the results obtained for a new generation of metal-organic framework open up new prospects for the development of kinetically selective HPLC [2, 3]. The current state and prospects of using kinetically selective chromatography for use in analytical chemistry are discussed.