Polarity and hydrophilicity – principal independent characteristics of chromatographic stationary phases

Abstract

The goal of this work is the development of a new method of classification of chromatographic
stationary phases (SP) on the fundamental basis. In this paper, the well-known approaches Keesom and
Debye, which are supplemented by conclusions of the theory of generalized charges (TGC) and a quantummechanical
estimate of the parameters of the hydrogen bond. Generalized charge (GC) is a function of the
number, state function, and distance from the point of interaction of the valence electrons of the molecule.
TGC was a key instrument to describing the adsorption and create a method in general. With it derived an
expression for the energy of intermolecular interactions, which comprises three independent terms: one term
is a characteristic of the non-polar energy, which can be determined by means of generalized charges; second
- the characteristic of polar forces associated with the presence of dipole moments in at least one of the
interacting objects; third - the characteristic of hydrogen bond, which depends on the probability of its
formation. Condition of their interference is determined by the equilibrium distance corresponding to the
minimum of the total energy.
We propose and derive the relative characteristics of polar forces and hydrogen bonds, named
«polarity» and «hydrophilicity», respectively. Polarity parameter is the ratio of square of the dipole moment
to GC. Hydrophilicity parameter is the ratio of the probability of formation of the hydrogen bond to the GC.
Thus, SP parameters involve two independent quantities - polarity and hydrophilicity.