GENERAL NONEQUILIBRIUM THEORY OF CHROMATOGRAPHY WITH COMPLEX FLOW TRANSPORT

The nonequilibrium theory of chromatography is developed in general terms for complex laminar flow involving local fluctuations in the direction and magnitude of the velocity vector. This theory leads to an effective diffusion coefficient which describes zone dispersion. It is shown that flow complexities are responsible for the phenomenon of coupled eddy diffusion" and the attendant transition of the effective diffusion coefficient from a second-power to a first-power dependence on flow velocity. Failure to account for this important phenomenon may lead to an error of several orders of magnitude. The two limiting cases and the transition region itself are discussed. The order of magnitude of equilibrium departure and the validity of the basic assumptions are established. The problems of devising realistic models for chromatographic media are also mentioned."