Preparation and Evaluation of 2 m Long Open Tubular Capillary Columns of 50 μm Internal Diameter for Separation of Peptides in Liquid Chromatography

A 2 m long open tubular column with a copolymer layer fabricated on the inner surface of silica capillary of 50 μm id has been prepared. A ligand with a terminal halogen was bound to the capillary inner surface via silanol-isocyanate reaction and an initiator moiety was introduced by reacting with the terminal halogen. Then a thick layer of linear copolymer chains was generated on the inner surface of capillary by reversible addition-fragmentation transfer polymerization of styrene and N-phenyl acrylamide. The resultant open tubular column exhibited a remarkably high separation efficiency for the separation of a synthetic mixture of five peptides in liquid capillary chromatography (in the pressure mode). The effect of monomer mixing ratio (styrene versus N-phenyl acrylamide) on the chromatographic separation efficiency has been studied. The column prepared with the optimum mixing ratio produced the number of theoretical plates (N) of 391,200 per column under the optimized elution pressure. The column to column repeatability estimated as relative standard deviation in plate count, retention factor, asymmetry factor, and resolution was found better than 3.0%.