[Study on the determination of peptide mixture by HPCE]

A rapid method for the simultaneous assay of 7 peptide mixture, including angiotensin I, II, III, substance P, neurokinin, somatostatin and neurotensin, by high performance capillary electrophoresis has been established. The nature, pH and concentration of buffer, running voltage, detection wavelength, injection time and the effective length of amino-coated capillary were defined with the results of experiment. With 50 mmol/L ammonium acetate (pH 4.5) as running buffer and siphonage injection for 10 seconds, the measurements were carried out at 25 degrees C and 10 kV running voltage [(-)-->(+)] applied to a 57 cm x 75 microns i.d. (50 cm effective length) amino-coated capillary. The 7 peptide mixture was determined by a UV detector at 214 nm. The total time for separation and determination was within 8 min. The recoveries ranged from 95% to 98% with RSD from 2.9% to 4.2%. It has been found that the 75 microns i.d. capillary has higher sensitivity than 50 microns, but its efficiency and Rs were worse.