Low affinity pair size exclusion chromatography (LAPSEC) is herein described as a novel approach specifically for lectin based monosaccharide separation but with the potential for wider application using weak antibody-antigen interactions. This technique exploits weak ligand receptor interactions and the difference in molecular size between free and receptor-bound ligand, to effect separations using a size exclusion chromatographic column. While such carrier-based separations are achievable with high affinity interactions, the advantage of the approach described here is that the use of weak interactions also allows separation of ligand from carrier in the same column, allowing recycling of the carrier. The utility of the LAPSEC approach is shown by results obtained using Concanavalin A and Lotus Tetragonolobus lectin to separate their specific monosaccharides (D-mannose and L-fucose, respectively) from unbound monosaccharides. These systems have been simulated using a simple multi-sectional equilibrium model using independent measurements of binding constants. The results show that monosaccharide separation and recovery of lectin is feasible in a single run and suggests that this approach may have potential for the selective recovery of low molecular weight products on a preparative scale. As receptors are not immobilized, resin costs are reduced, there is efficient use of affinity receptor, and separation is achieved under isocratic conditions.