Abstract Elution chromatography under non-retained conditions and frontal chromatography in retained conditions using various proteins (bovine serum albumin, myoglobin and ovalbumin) and POROS Q/M large-particles (PerSeptive Biosystems, Cambridge, MA, USA) were studied. Elution experiments show that the mass transfer mechanism which allows improved performance of perfusion chromatography is intraparticle convection. Convection enhances intraparticle diffusivity; the concept of “augmented” effective diffusivity was used to explain both peak sharpening and the modified Van Deemter equation for large-pore particles. Experimental adsorption isotherms were measured from experimental breakthrough curves. In the high concentration range (above 1 mg ml −1) the isotherm is rectangular; however, data in the low concentration region show that the Langmuir equation better represents the whole isotherm. A simple fixed-bed model based on a rectangular adsorption isotherm was used in the simulation of breakthrough curves and augmented effective diffusivities were calculated. The dependence of the augmented effective diffusivity on the superficial velocity agrees well with the relationship derived by Rodrigues et al. (A.E. Rodrigues, B. Ahn and A. Zoulalian, AIChE J., 28 (1982) 541). Similar results were obtained by using the Langmuir isotherm in a more detailed modelling of the chromatographic column.