S. V. Kurbatova

Laws of sorption of some aromatic heterocycles from solutions on nanoporous supercrosslinked polystyrene

Principles of the sorption of 5-tetrazole, 1,3,4-oxadiazole, and 1,2,4,5-tetrazine derivatives from solutions of various composition on nanoporous supercrosslinked polystyrene were studied by high performance liquid chromatography. The influence of the nature of heteroatom on the sorption of these heterocycles was demonstrated. The role of different types of intermolecular interactions in the sorption of the studied substances from solutions on nanoporous supercrosslinked polystyrene in quasi-normal phase and reverse phase liquid chromatography are discussed.

Thermodynamics of sorption of 1,3,4-oxadiazoles and 1,2,4,5-tetrazines according to reversed phase high-performance liquid chromatography

The thermodynamics of sorption of several 1,3,4-oxadiazoles and 1,2,4,5-tetrazines on octadecyl silica gel from aqueous acetonitrile solutions of different compositions has been studied. The thermodynamic characteristics of the chromatographic systems under study were calculated. The dependences of the standard molar change in the entropy term of the dependence lnk-1/T and the enthalpy after the transfer of the sorbate from bulk solution to the surface layer on the content of the organic component in the eluent were analyzed for the compounds. It was shown that the structure of sorbate molecules affected the thermodynamic characteristics of their quasichemical sorption and solvation. Tendencies of compensation were found for sorption and solvation of the heterocyclic compounds under study.

The influence of the structure of some aromatic heterocyclic derivatives on their retention in reversed-phase high-performance liquid chromatography

The chromatographic behavior of aromatic heterocyclic derivatives in reversed-phase high-performance liquid chromatography was investigated. The retention characteristics of the substances under the conditions of chromatography with water-acetonitrile mobile phases (retention factors, relative retentions, distribution coefficients, Henry adsorption constants, differences in the differential molar energy of sorption, and Gibbs energies of sorption) were determined. It was shown that the chromatographic retention of the sorbates depended on their molecular structure. The influence of the nature of heteroatoms and their number on the sorption of heterocyclic compounds was discussed.

Models of retention of adamantylamidrazones in reversed-phase high-performance liquid chromatography

Rules governing the chromatographic behavior of some amidrazones of the adamantane series were studied under the conditions of reversed-phase high-performance liquid chromatography. The characteristics of the retention of sorbates in elution by aqueous-acetonitrile phases with various compositions were calculated. Correlations between the structure and physicochemical characteristics of sorbate molecules and their retention were studied.

Chromatographic retention of adamantylamidrazones and triazoles by octadecyl silica gel and hypercrosslinked polystyrenes from water-acetonitrile solutions

Peculiarities of the chromatographic behavior of adamantylamidrazones and adamantyltriazoles on octadecyl silica gel and hypercrosslinked polystyrenes in the conditions of reverse phase high performance chromatography are investigated. A comparative analysis of the effect of structures and physicochemical characteristics of sorbate molecules on the Gibbs free energy of sorption for the investigated sorbates is performed.

Features of the adsorption of aryl- and hetaryl-substituted 1,3,4-oxadiazoles from solutions on the surface of porous graphitic carbon in Henry’s range

Adsorption in Henry’s range of structurally related aryl- and hetaryl-substituted 1,3,4-oxadiazoles from n-hexane-dichloromethane and water-acetonitrile solutions on the surface of porous graphitic carbon (PGC) under the conditions close to equilibrium is studied by high-performance liquid chromatography. The characteristics of sorption of 1,3,4-oxadiazoles from solutions on the surface of this adsorbent, octadecyl silica gel, and on hypercrosslinked polystyrene are compared. It is shown that the structure of the molecules and their Van der Waals surface area and polarity affect adsorption on a PGC surface. A variant of the mechanism of adsorption of the polar molecules on the PGC surface, explaining the anomalously high values of their Henry constants of adsorption and based on the planar location of the 1,3,4-oxadiazoles molecules with respect to the adsorbent surface and the specific adsorbate-adsorbent intermolecular interaction in addition to the background dispersion interactions, is proposed. It is established that the linear the Gibbs energy relationship upon the adsorption of the studied compounds from n-hexane-dichloromethane and water-acetonitrile solutions on the PGC surface holds.

The retention of some azoles in reversed-phase liquid chromatography

The influence of the structure-related physicochemical properties of derivatives of nitrogen-containing heterocyclic compounds on their retention under the conditions of reversed-phase liquid chromatography was studied. The dependence of the chromatographic retention of azole derivatives on the composition of the mobile phase was determined. The presence of azole protonated forms was substantiated by conductometric data.

The Influence of the Eluent Composition on the Retention of Derivatives of Some Aromatic Heterocyclic Compounds in Reversed-Phase High-Performance Liquid Chromatography

The influence of the composition of water-acetonitrile eluents on the retention of derivatives of aromatic heterocyclic compounds in reversed-phase high-performance liquid chromatography was studied. The coefficients of the displacement of acetonitrile molecules from the adsorption layer and equilibrium constants of quasi-chemical reactions of sorption and solvation of sorbate molecules were determined. For the investigated chromatographic systems, the applicability scope of the basic adsorption retention models are discussed.

Quasi-normal phase chromatography of nitrogen-containing adamantane derivatives

The chromatographic retention of adamantyl-containing amidrazones and triazoles is studied under the conditions of quasi-normal phase (QNP) and reversed phase high-performance liquid chromatography using partially sulfonated hypercrosslinked polystyrene as a stationary phase. The considerable effect of the sorbent-sorbate π interactions on the retention factor of the analytes, particularly under conditions of QNP chromatography, is revealed.

Regularities of the sorption of cycloalkenyl-substituted thiophenes and 2,2′-bithiophenes from water-acetonitrile solutions on hexadecyl silica gel under conditions of high-performance liquid chromatography

Regularities of the sorption of newly synthesized cycloalkenyl-substituted thiophenes and 2,2′-bithiophenes from water-acetonitrile solutions of different compositions on hexadecyl silica gel are investigated by high-performance liquid chromatography (HPLC). The retention factors and Henry constants of adsorption of these substances are determined. We discuss the effect of the molecular structure of the investigated heterocycles, and the nature and positions of the substituents, on the sorption. The equilibrium constants for the quasi-chemical reactions of sorption of the investigated compounds at the interface, and their solvation in a multicomponent bulk solution, are calculated using the Lanin-Nikitin equation. Based on the obtained results, we suggest that structural self-organization in the bulk solution and at the interface with the hydrophobic surface of hexadecyl silica gel plays an important part in the sorption of cycloalkenylsubstituted thiophenes and 2,2′-bithiophenes from multicomponent solutions.