Jan K. Rozylo

Separation of optical isomers of amino acids on modified chitin and chitosan layers

The possibilities of separation of seven D,L-mixtures of amino acids on chitin, chitosan beds and their modifications are tested, using TLC methods. From investigated stationary phases chitin modified by Cu2+ ions may be used for separation of optical isomers of amino acids. The best results have been obtained in chromatographic systems with ternary mobile phases.

Thermodynamic Description of Liquid-Solid Chromatography Process in the Optimization of Separation Conditions of Organic Compound Mixture

Abstract Continuous interest in chromatographic methods as analitical techniques of different compounds separation gives rise to studies on theoretical description of chromatographic systems and, at the same way, to the selection of the best way of the prediction of chromatographic separation results. The main problem of theoretical studies in adsorption chromatography is to describe precisely correlations between retention parameters of given solute and mobile phase composition. In present paper the effort was made to use thermodynamic description of adsorbent - binary solvent - substance systems for theoretical predictions of analytical separation results in high-performance liquid column and thin-layer chromatography. The attention was paid to the possibility of using thin-layer chtomatography as a method of an initial choice of chtomatographic process optimization.

Thin-layer and overpressured-layer chromatography for evaluation of the hydrophobicity of s -triazine derivatives

The retention factor in pure water, log kw, is proposed as a measure of the hydrophobicity of s-triazine derivatives. In these studies two reversed-phase techniques, thin-layer chromatography (TLC) and overpressured-layer chromatography (OPLC), were used. The effects of the chromatographic system, i. e. mobile and stationary phase properties, on log kw were analyzed to select the best system for determination of the hydrophobicity of the compounds. In TLC the chemically bonded phases RP-18 and RP-CN were used as stationary phases and acetone, acetonitrile, tetrahydrofuran, and dioxane as organic modifiers of the mobile phases. In OPLC RP-8 and RP-18 stationary phases and water-acetonitrile mobile phases were used. The values of log kw, determined by linear extrapolation and by the new method based on Oscik’s equation, were compared with log P values calculated by different theoretical methods. In TLC the best linear correlations between log P and log kw were observed for water-dioxane as mobile phase on both RP-18 and RP-CN stationary phases whereas in OPLC very good relationships were obtained for all the systems applied. Better functions for correlation of log P with log kw were obtained for log kw values determined by the method developed from Oscik’s equation.

Determination of Association Effects in TLC Data for Different Solutes Chromatographed in Methanol-Acetone on Silica Gel

Abstract The TLC data for different solutes chromatographed in methanol-acetone mobile phase on silica gel at 293 K are analysed by means of the theoretical equations discussed in the previous paper (1). This analysis shows that for the above systems the solute-solvent and solvent-solvent association and the composition of the surface phase play an important role. The composition of the surface phase has been determined by utilizing the excess adsorption data of methanol from acetone on silica gel.

The effect of electric fields on solute migration and mixture separation in TLC

The effect of electric fields on mobile phase migration velocity and on the retention of chromatographed solutes has been investigated for so-called horizontal electric fields with sample applied at the anode and cathode ends of the plates. An electric field can also affect the surfaces of stationary phases. These investigations were performed in a so-called vertical electric field at a gradient voltage 12 kV cm−1. The effect of the electric field on the apolar component of the surface free energy was determined for six popular stationary phases; for silica and aluminum oxide it was possible to determine the acidic and basic components of the surface free energy. The effect of electric fields on the zeta potential of silica-methanol and aluminum oxide-water systems was also demonstrated.

Theoretical calculation of the optimum separation in thin-layer chromatography

SummaryUp to now the optimum composition of a binary mobile phase for separation in thin-layer chromatography has been determined mainly by the method of successive trials. In this paper a simple way is presented to determine the mobile phase composition and the maximum difference in the RM values of two substances. The equation introduced has been illustrated with examples of adsorption thin-layer chromatography on magnesium silicate. Calculation of the largest difference in the RM values of two substances in relation to the composition of the binary mobile phase has been compared with the corresponding values determined experimentally. A good agreement of the obtained theoretical data and experimental values has been found.

The Correlations between Capacity Factors k′ and RM Values in Liquid Column and Thin-Layer Chromatography

Abstract The purpose of this studie being carried out is to define some regularities between Thin-layer and Liquid Column Chromatography; i.e. between experimental obtained and theotetical calculated RM-values and experimental obtained logk-values for some non-active organic substances in mixed binary solvents systems. It was studied the kind these correlations change with changing mobile phase compositions. The present paper is a certain aspect of new studies on possibilities of the use Thin-layer Chromato-graphy as a pilot technique for Liquid Column Chromatography (1,2). In a study on the optimization of chromatographic process it is necessary to define the correlations between RM-values which characterize the retention in TLC and k′-values which characterize the retention in in LCC. In the paper the changes of these correlations with the changes of mobile phase compositions are studied. The conformity between theoretical calculated and experimental obtained RM-values of chromatographed substances for ...

Characterization of Chromatographic Systems with Ternary Mobile Phase

Abstract A new equation for description of the RM values obtained by adsorption TLC with ternary mobile phase is examined for naphthalene isomers in tetrachloride carbonchloroform-methanol and tetrachloride carbon-chloroformacetone solvents mixtures on silica gel at 24°C. This equation creates a possibility to calculate the RM values for a given substance in ternary solvent mixture by means of the RM values for this substance in the single solvents and so-called heterogeneity parameter m.

Thin-layer chromatography with an isolated support and forced flow of the mobile phase

The first group includes paper chromatography and classic thinlayer chromatography [1–4]. The mobile phase can migrate up the plates – the so-called ascending technique – or through a horizontal adsorbent layer in a so-called sandwich chamber. All techniques in which the mobile phase migrates by capillary action are characterized by decrease in the velocity of the mobile phase with increasing development distance. The velocity of migration of the mobile phase in classical TLC techniques depends on the type of stationary phase, its particle size, and the properties of a mobile phase – density, viscosity, and surface tension. In such chromatographic systems the mobile phase velocity is not often optimum; this reduces the efficiency of the chromatographic system [1–4].

Possibility of calculating the Rm values in thin-layer chromatography using a ternary mobile phase

SummaryOn the basis of an equation derived it is possible to establish theoretically the RM values for a ternary mobile phase. The RM values of phenol and its derivatives, naphthalene and its derivatives and some polycyclic aromatic hydrocarbons were measured. A good agreement has been found between the calculated and the experimentally obtained RM values. Analysis of the results showed some regularities of certain values obtained in binary systems when related to the ternary mobile phase.