Band broadening peak shape models

The ideal model and the equilibrium-dispersive model are the two important subclasses of the equilibrium model. The ideal model completely ignores the contribution of kinetics and mobile phase processes to the band broadening. It assumes that thermodynamics is the only factor that influences the evolution of the peak shape. We obtain the mass balance equation of the ideal model if we write > =0 in Equation 10.8, i.e., we assume that the number of theoretical plates is infinity. The ideal model has the advantage of supplying the thermodynamical limit of minimum band broadening under overloaded conditions. 

The band broadening function G(V)i can be determined for several particle sizes by analyzing latex samples of known particle size which have very narrow size distributions, and then mathematically modeling the shape of the resulting chromatographic peaks. 

These mathematical models enable prediction of isothermal or temperature-programmed retention times with very good accuracy, and so chromatographers can estimate the effects of changing conditions on peak elution sufficiently well to provide a good basis for optimization. These models do not take into account any of the band-broadening processes that determine peak shapes, and therefore alone they cannot predict peak resolution, Trennzahl or separation number, or any other measurement of chromatographic quality. 

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