SEPARATION OF BIOLOGICALLY-ACTIVE PEPTIDES BY CAPILLARY ELECTROPHORESIS AND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

HPLC and CE have been applied to the separation of some newly synthesi zed substances, including nonapeptides from the intrachinary region of insulin, insulin-like growth factors I and II (IGF I and II) and some penta- and hexapeptides. All the peptides are satisfactorily. separat ed using a reversed-phase HPLC system with a C-18 stationary phase and mobile phases of 20-40% acetonitrile (v/v) and 0.2% trifluoroacetic a cid in water (v/v). The best CE separation of IGF I and II has been ac hieved in a 30 mM phosphate buffer (pH 4-5), whereas 150 mM phosphoric acid (pH 1.8) is optimal for the insulin nonapeptides. The latter ele ctrolyte is also suitable for the CE separation of the hexapeptides, a s is a micellar system containing 20 mM borate-50 mM sodium dodecyl su lfate (pH 9.0). Complete CE resolution of the D- and L-forms is possib le in a 50 mM phosphate buffer (pH 2.5) containing 10 mM beta-cyclodex trin. UV spectrophotometric detection was used throughout, at waveleng ths from 190 to 215 nm. The CE procedures are, in general, preferable to HPLC separations, as they exhibit better separation efficiencies, a re faster and consume smaller amounts of analytes and reagents.