Comparison of particle size and flow rate optimization for chromatography using one-monomer molecularly imprinted polymers versus traditional non-covalent molecularly imprinted polymers

The dependence of enantio-selective chromatographic performance on particle size, as measured by separation factor, was investigated for one-monomer molecularly imprinted polymers (OMNiMIPs) compared to traditionally formed EGDMA/MAA molecularly imprinted polymers (MIPs). Five particle size ranges were compared (< 20 mu m, 20-25 mu m, 25-38 mu m, 38-45 mu m, and 45-63 mu m), revealing that the particle sizes above 25 mu m provided the highest separation factor, and thus the best enantionter separation, for both imprinted polymers. Other chromatographic parameters such as the number of theoretical plates and resolution exhibited only minor changes for the OMNiMIPs as the particle size changed, except for particles 20 mu m and below. However, the number of theoretical plates and resolution for EGDMA/MAA are higher for particles in the 20-25 mu m range. Thus, chromatographic factors for the EGDMA/MAA polymers are better in this range, despite better enantioselectivity for particle sizes above 25 mu m. In contrast, OMNiMIPs generally show the most favorable performance for particle sizes in the 38-45 mu m range. It was also found that decreasing flow rate resulted in improved enantioselectivity for both MIPs for all particle sizes. (c) 2005 Elsevier B.V. All rights reserved.