Linear chromatography thermodynamic studies

Thermodynamic Studies by Linear Chromatography. The first one is under linear chromatography conditions at variable temperature making use of the van t Hoff equation (Equations 1.13 and 1.14) [48,50,52,53,89],... 

Similarly, the coefficients of the isotherm are considered as independent of the pressure and constant along the column. This is in agreement with what we know regarding the constancy of the retention factors imder linear conditions in Hquid chromatography. Careful studies, however, have shown that this is approximate. Fundamental thermodynamics shows that [23] ... 

What is the relative importance of thermodynamic effects compared to the kinetic sources of band broadening already known to exist from studies in linear chromatography ... 

In ideal chromatography, we assume that the column efficiency is infinite, or in other words, that the axial dispersion is negligibly small and the rate of the mass transfer kinetics is infinite. In ideal chromatography, the surface inside the particles is constantly at equilibrium with the solution that percolates through the particle bed. Under such conditions, the band profiles are controlled only by the thermodynamics of phase equilibria. In linear, ideal chromatography, all the elution band profiles are identical to the injection profiles, with a time or volume delay that depends only on the retention factor, or slope of the linear isotherm, and on the mobile phase velocity. This situation is unrealistic, and is usually of little importance or practical interest (except in SMB, see Chapter 17). By contrast, nonlinear, ideal chromatography is an important model, because the profiles of high-concentration bands is essentially controlled by equilibrium thermodynamics and this model permits the detailed study of the influence of thermodynamics on these profiles, independently of the influence of the kinetics of mass transfer... 

---