ABSTRACT
The theory behind peak dispersion is somewhat complex and can be explained partly by the plate theory but more completely by another theory originated by Van Deemter called the Rate Theory. Van Deemter and others considered that four spreading processes were responsible for peak dispersion, namely, multi-path dispersion, longitudinal diffusion, resistance to mass transfer in the mobile phase and resistance to mass transfer in the stationary phase. Any chromatogram can be presented as a curve relating solute concentration in the mobile phase to volume flow and this is the variable used in the plate theory. It is necessary to consider the effect of change in linear velocity and pressure along a GC column on the different dispersion processes that are taking place. Obviously the multi-path term which contains no parameters that depend on the velocity or gas pressure will be unaffected and the expression that describes it will remain the same.
