Stochastic simulation of the partition mechanism under diffusion-limited conditions in chromatography and electrochromatography

Abstract

A three-dimensional stochastic simulation has been used to study the kinetics of the partition mechanism in a homogeneous system under diffusion-limited conditions. By nonlinear regression of the simulation data, the rate constants for transport between the fluid and surface phases ( k fs and k sf) are determined with ±0.49% average relative standard deviation, and the ratio of the rate constants ( k fs/ k sf) with ±0.70% average relative standard deviation and ±2.25% average relative error. The results of these simulations are used to elucidate the relationship between the rate constants and the fundamental parameters of the system, including the equilibrium constant ( K), the diffusion coefficients ( D f and D s), and the radius of the fluid and surface phases ( R f and R s). In addition, the influence of slow kinetics on the solute zone profile is characterized under the conditions of laminar and electroosmotic flow. The mean, variance, and asymmetry of the zone profile are shown to vary systematically with the rate constants, the linear velocity, and the distance travelled.