Chapter 14 - Physicochemical property determinations by liquid chromatography

Abstract

The physicochemical properties that can be determined by retention and band broadening measurements in liquid chromatography include solvent-based properties inferred from equilibrium processes occurring predominantly in the mobile phase, surface properties of materials which can be used as stationary phases inferred from solute–stationary phase interactions, and diffusion-controlled processes inferred from retention and band broadening. In addition, physicochemical properties can be estimated indirectly from surrogate chromatographic models of chemical, environmental, and biological systems using correlation models. Examples of physicochemical properties determined by direct methods include equilibrium constants (partition, acid dissociation, formation, protein binding), molecular descriptors for solute–solvent interactions, soil–water distribution constants, and surface properties of solids by inverse liquid chromatography. Examples of physicochemical properties determined by indirect methods include lipophilicity, octanol–water partition constant, normalized soil–water equilibrium constant, non-specific toxicity to fish and microorganisms, and membrane permeation coefficients for blood–brain, blood–tissue, and skin–water barriers. The uncertainty in direct measurements is primarily a result of the heterogeneous structure of solvated stationary phases and changes in the retention mechanism for varied solutes and for indirect measurements by the limited number of suitable chromatographic models for estimating physicochemical properties.