Reversed-Phase High-Performance Liquid Chromatography and Capillary Electrophoresis in the Stability Study of the Neuropeptide Growth Factor Antagonist [Arg 6,D-Trp 7,9,MePhe 8]-Substance P {6-11}: A Comparative Study

Abstract

Reversed-phase high-performance liquid chromatography and capillary zone electrophoresis are widely used in protein and peptide analysis. Degradation of the basic peptide [Arg 6, D-Trp 7,9, MePhe 8]-substance P {6-11} (antagonist G) was monitored with reversed-phase high-performance liquid chromatography, free capillary zone electrophoresis, and capillary zone electrophoresis with a capillary cationic coating. Capillary zone electrophoresis with a dynamically coated capillary provided better separation between antagonist G and its degradation products (formed at pH/H — 13) than high-performance liquid chromatography and free zone capillary electrophoresis. Rate constants of the alkaline degradation of antagonist G measured with reversed-phase high-performance liquid chromatography and capillary zone electrophoresis with a dynamic coated capillary wall are similar whereas the values measured with free zone capillary electrophoresis are lower. Rate constants for the degradation of antagonist G in acidic media are comparable for the three techniques. It is concluded that capillary zone electrophoresis using a dynamic coating with Fluorad is the most suited of the above-mentioned techniques in analyzing antagonist G and its degradation products.