Moment analysis of chromatographic behavior of separation media for fast HPLC.

The van Deemter equation and moment equations were used for analyzing the flow rate dependence of HETP experimentally measured in order to clarify chromatographic behavior from the kinetic points of view in columns packed with C18-silica monolith and C18-core-shell particles under RPLC conditions. They provided some information about molecular diffusion, eddy diffusion, and mass transfer kinetics in the columns. Additionally, the value of intra-stationary phase diffusivity was determined in the range of 10(-7)-10(-6) cm(2) s(-1) by the moment analysis. Information about the contribution of the mass transfer resistance in the external liquid film around the stationary phase to HETP was also obtained. Its contribution increases with an increase in the flow velocity of the mobile phase. It was concluded that the moment equations can provide more detailed information about the kinetic behavior in the columns than the van Deemter equation.