Molecularly imprinted polymer films grafted from porous or nonporous silica: Novel affinity stationary phases in capillary electrochromatography

Abstract

Molecularly imprinted composite materials were evaluated as chiral stationary phases in capillary electrochromatography (CEC). These consisted of spherical silica particles of different sizes and of different porosities, containing a surface-immobilized layer of molecularly imprinted polymer (MIP) targeted to bind L-phenylalanine anilide. Fused silica capillaries were packed over a length of 8.5 cm, using a pneumate amplification pump, and the stationary phase thus obtained was tested with respect to its electrochromatographic performance. The electroendosmotic flow (EOF) mobility was evaluated with respect to the content of grafted polymer, as well as the ionic strength and the acetonitrile content of the electrolyte. Moreover, the influence of the layer thickness and of the stationary phase porosity on the performance and on the sample load capacity was investigated. The packings exhibited different relative efficiencies for the two enantiomers. The results were discussed in terms of differencies in accessibility to the binding sites of the packings and of the mechanism of EOF generation. In the wide context of the different approaches so far proposed for MIP stationary phases in CEC, these materials can be a good alternative, worthy of further development and application, not restricted to chiral separations.

Analytical separations in open‐tubular capillary electrochromatography

“…This gives rise to a material that is filled with cavities, and one that is complementary in size, shape, and chemical functionality to the imprint molecule. These cavities enable the polymer to rebind the original template molecule [98,99,189,191,[193][194][195][196][197].…”

Biomimetic Polymers for Chiral Resolution and Antifreeze Applications

“…In a series of papers, Sellergren described the development of MIP films by grafting methods. [102][103][104][105][106][107] His group used silica particles bearing surface-immobilized, free radical azo-initiator species to favor grafting polymerization on the particle's surface over polymer growth in solution. In his research, L-phenylalanine anilide was used as a template in the polymerization of MAA and EDMA functionalized monomers.…”

Recent accomplishments in the field of enantiomer separation by CEC

“…Quaglia et al [78] employed the MIP technology for the preparation of silica particles chirally functionalized with a surface-immobilised layer of a MIP targeted to bind L-phenylalanine anilide. Hence, initiator-modified silica particles were suspended in a solution of the functional monomer methacrylic acid (MAA), the cross-linker ethylene dimethacrylate (EDMA), solvent (CH 2 Cl 2 or toluene) and L-Phe anilide as template (Fig.…”

“…Hence, initiator-modified silica particles were suspended in a solution of the functional monomer methacrylic acid (MAA), the cross-linker ethylene dimethacrylate (EDMA), solvent (CH 2 Cl 2 or toluene) and L-Phe anilide as template (Fig. 16) [78] and the polymerization was started by UV-initiation. Capillary columns (100 mm id) of 8.5 cm effective bed length were then packed with the MIPgrafted silica particles.…”