PEAK RESOLUTION IN LINEAR CHROMATOGRAPHY - EFFECTS OF INTRAPARTICLE CONVECTION

The quantitative relationship between separation performance and intra particle convection in large-pore, permeable supports for chromatograp hy is examined. A model for linear chromatography is used in the analy sis for particles that contain both throughpores where diffusive and c onvective transport occur and purely diffusive micropores. The key con cept is that of a convection-augmented intraparticle diffusivity, whic h depends only on the intraparticle Peclet number, lambda. The separat ion performance is expressed in terms of both resolution and peak prof iles at the column outlet. It is shown that, for given operating condi tions, the separation enhancement obtained for intraparticle convectio n is dependent on the relative importance of throughpore and micropore diffusion rates. In the absence of micropore resistances, the resolut ion is always increased by intraparticle convection. The latter, howev er, is shown to have no effect on the separation performance when micr opore diffusional resistances are dominant. Relationships necessary to assess the importance of these effects for linear chromatography cond itions are provided.