The activity behaviors of particle based and monolithic immobilized enzyme reactors (IMERs) developed for proteomics applications in semi-micro-liquid chromatography were comparatively investigated. For monolithic IMER, the plain monolith was synthesized by in situ thermal copolymerization of glycidyl methacrylate (GMA) and ethylene dimethacrylate (EDM) in fused silica capillary. For particle based IMER, monodisperse-porous poly(GMA-co-EDM) beads 6.8 mu m in size were synthesized by staged-shape template polymerization and used as support in a stainless steel microbore column. alpha-Chymotrypsin (CT) was covalently attached onto the particle based and monolithic supports via amination and glutaraldehyde coupling stages. In the case of monolithic IMER, higher final substrate conversions were achieved particularly with high substrate feed rates with respect to particle based IMER probably due to the convective diffusion in the macropores of continuous monolithic block. The final substrate conversion increased with increasing substrate feed concentration for monolithic IMER while a decrease was observed for particle based IMER. Hence monolithic IMER was superior when high substrate feed concentration was used with sufficiently high substrate feed flow rates.(C)2013 Elsevier B.V. All rights reserved.