A novel monolithic column for capillary electrochromatographic separation of oligopeptides

A monolithic column was prepared using L-phenylalanine as template and a covalent approach through the formation of Schiff base with o-phthalaldehyde (OPA). OPA, allylmercaptan, L-phenylalanine, and triethylamine were stirred at first, then methacrylic acid, 2-vinylpyridine, ethyleneglycoldimethacrylate,alpha,alpha-azobisisobutyronitrile, and 1-propanol were added to the reaction mixture. The resulting material was introduced into a capillary column. Following thermal polymerization, the template was then extracted with a mixture of HCl and methanol. The column was employed for the capillary electrochromatographic separation of oligopeptides. A capillary column of 75 (50) cm x 75 mu m ID with a mobile phase of phosphate buffer (pH 7.0, 40 mM)/methanol (5%, v/v), an applied voltage of + 15 kV, and detection at 214 nm, could baseline separate angiotensin I, angiotensin II, [Sar(1), Thr(8)] angiotensin, oxytocin, vasopressin, tocinoic acid, P-casomorphin bovine, P-casomorphin human, and FMRF amide within 20 min. The separation behavior of the templated polymer was also compared with that of the non-templated polymer. As a result, it can be concluded that the electrochromatographic separation of this set of peptides was mediated by a combination of electrophoretic migration and chromatographic retention involving hydrophobic, hydrogen bonding, electrostatic as well as the Schiff base formation with OPA in the cavity of the templated polymer. (c) 2006 Elsevier B.V. All rights reserved.