Open tubular capillary column of 50 μm internal diameter with a very high separation efficiency for the separation of peptides in CEC and LC.

A specially designed long open tubular capillary column (50 μm internal diameter and 112 cm effective length) was prepared by fabrication of a thin three-component co-polymer layer on the inner surface of silica capillary. A pretreated silica capillary was reacted with 4-(chloromethyl)phenyl isocyanate in the presence of dibutyltin dichloride as catalyst followed by sodium diethyl dithiocarbamate. Then a thin polymer layer was made on the inner surface of capillary by reversible addition-fragmentation transfer polymerization of styrene, N-phenylacrylamide, and methacrylic acid. A carefully adjusted formulation of reaction mixture and elaborated procedures were adopted to secure formation of the co-polymer layer of enhanced separation performance. The co-polymer immobilized open tubular capillary column was used for the separation of a synthetic mixture of five peptides and excellent separation efficiency (over 1.7 million per column) was obtained in the capillary electrochromatography mode. Such excellent separation efficiencies of ca. 1 m column have not been obtained in the isocratic elution mode so far. The column was also used for separation of the peptides in the liquid chromatography mode to show very good separation efficiency (average 286 700 per column).