Linear equilibrium, size exclusion

The functions /,(, /) and fi(x,t) allow solutions to be derived for special cases of inlet and initial conditions. Note that 5 is a dummy variable of integration. In the case where the column has been washed with eluent and a sample has not been introduced, initial condition 3 from Table I applies, and f 1 (x,t) = 0. After a sample has been introduced and washed into the column by eluent, boundary condition 1 from Table I with c = 0 applies and f x,t) = 0. The eluent volume is Q — Avta. The two limiting cases mentioned above may be superimposed, offset from one another by A v a t = Q = VF where Q is the feed volume. This superimposition is applicable only in the case of linear equilibrium, which yields symmetric solutions. Figure 4 shows the results of these equations graphically for selected values. These values may be particularly applicable to proteins in size exclusion supports. 

In size exclusion chromatography, components are excluded from the resin on the basis of size. By definition, solutes are not absorbed. These supports have a linear equilibrium, since a constant volume within the resin is available for a given size solute. When the support comes to equilibrium with the mobile phase, the volume in the pores available to the solute will have the same molar concentrations as the surrounding mobile phase. 

Enthalpy and entropy compensation phenomena have been found not only in the chromatographic analysis of polymers but also in many kinds of kinetic and equilibrium processes for which a linear relationship exists between AH and AS [52, 53]. In the LCCC analysis of synthetic polymers, it is generally assumed that the retention of polymers is balanced by unfavorable entropic effect due to the size exclusion mechanism (AS < 0) and the favorable enthalpic effect due to the solutestationary phase interaction (AH < 0) [54—56]. Consequently, it is expected that a polymer species at the LCCC condition elutes independent of its molecular weight... 

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