COMPARISON OF POLYMER-COATINGS OF CAPILLARIES FOR CAPILLARY ELECTROPHORESIS WITH RESPECT TO THEIR APPLICABILITY TO MOLECULAR IMPRINTING ANDELECTROCHROMATOGRAPHY

In molecular imprinting (MI), interactive monomers and suitable cross- linking agents are polymerized in the presence of a template. Once the template has been removed, the remaining space acts as a highly speci fic binding site for the template or analogs thereof, due to the uniqu e three-dimensional arrangement of interaction points. Several steps a re involved in producing such a polymer coat inside a capillary electr ophoresis capillary. First, the silanization of the inner surface of t he capillary with a suitable silane is necessary, to link a monolayer of unsaturated groups suitable for polymerization to the capillary sur face. These monomeric groups are then integrated into the three-dimens ional polymer coat produced in the next step, MI-capillary coatings id eally are highly porous and of a thickness, delta, which is smaller th an the inner radius, r, of the capillary in question. Porous polymer n etworks can be produced by dispersive polymerization using a suitable solvent (porogen). However, the exact conditions for producing a coati ng suitable for capillary zone electrophoresis had to be determined ex perimentally. Seven porogens, namely hexane, toluene, tetrahydrofuran, acetonitrile, CHCl3, dimethyl sulfoxide and dimethylformamide, and tw o cross-linkers, namely ethyleneglycoldimethacrylate and divinylbenzen e, at concentrations of between 5 and 20% (v/v) were investigated. In about 20% of the combinations, a polymer coat of the desired qualities was obtained, The applicability of the MI capillaries to specific sep arations was demonstrated for the separation of a racemic mixture of S (+)- and R(-)-2-phenylpropionic acid. trans-3-(3-Pyridyl)-acrylic acid was used as the interactive monomer in this case. (C) 1997 Elsevier S cience B.V.