ABSTRACT
The source of migration in chromatography is the downstream motion of the mobile phase. People must clearly understand the measure of this motion in order to make quantitative sense out of migration. Frequent use is made of expressions such as column migration or processes within the column. The quantity R is the basic retention ratio characterizing migration rates. The quantities R and RF, while closely related, are sometimes mistakenly equated. Separation is achieved through differential migration. Hence the migration process is a cornerstone of chromatography. The latter definition leads us to the viewpoint that zone migration, despite its chaotic molecular origin, is related to equilibrium parameters. The above equations can be related more directly to the dynamics of sorption and desorption. It may, however, also involve nonlinear dynamic processes such as diffusion and kinetics.
