PEAK RESOLUTION IN LINEAR CHROMATOGRAPHY - EFFECTS OF INTRAPARTICLE CONVECTION

The quantitative relationship between separation performance and intraparticle convection in large-pore, permeable supports for chromatography is examined. A model for linear chromatography is used in the analysis for particles that contain both throughpores where diffusive and convective transport occur and purely diffusive micropores. The key concept is that of a convection-augmented intraparticle diffusivity, which depends only on the intraparticle Peclet number, lambda. The separation performance is expressed in terms of both resolution and peak profiles at the column outlet. It is shown that, for given operating conditions, the separation enhancement obtained for intraparticle convection is dependent on the relative importance of throughpore and micropore diffusion rates. In the absence of micropore resistances, the resolution is always increased by intraparticle convection. The latter, however, is shown to have no effect on the separation performance when micropore diffusional resistances are dominant. Relationships necessary to assess the importance of these effects for linear chromatography conditions are provided.