Possibility for the theoretical calculation of the function between the RM values and the composition of two-component solvent mixtures used as the mobile phase and its application for the calculation of the optimum separation conditions in liquid adsorption chromatography

Abstract

Multicomponent solvent mixtures are frequently applied as the mobile phases in high pressure liquid adsorption chromatography as well as in TLC. In order to find the optimum separation conditions for these chromatographic systems it is necessary to carry out a theoretical investigation of the process of adsorption from multicomponent systems. In the present work an equation has been derived which relates the values of the RM coefficients with the composition of a two-component mobile phase. The equation also describes the relationship between the values of this coefficient and the values of the RM coefficients for the same substance but chromatographed while using pure solvents as the mobile phases. by chromatographic or adsorption methods. It has been demonstrated that the RM1,2=f(x1) function and consequently, the shape of the curves, depend, to a considerable degree, on the type of the two-component solvent used, e.g. whether it represents an ideal or a conformal solution. The theoretical curves representing the RM1,2=f(X1) relationship have been compared with those obtained from measurements in actual chromatographic systems. It is also possible to determine this function theoretically for a given system and thus, calculate the values of ΔRM for specified substances. Consequently, one can predict the optimum seperation conditions in adsorption chromatography. It is also possible to determine the intermolecular interactions with help of the equation derived in this paper for chromatographic systems for which the empiric RM1,2=f(x1) relationships are known. This can be done by comparing the shape of the curves found with the shape of the theoretical curves.