Determination of angiotensins by capillary electrophoresis

A protocol to separate ten peptides of the angiotensin family by capillary electrophoresis was described. The experiment was carried out using the Waters Quanta 4000 Electrophoresis system and the steps taken to determine the optimum electrophoretic conditions include (i) the use of different electrolytes, (ii) variation of ionic composition and pH of the electrolytes, (iii) variation of applied voltage and the wavelength of ultraviolet detection. Successful separation of the ten angiotensin peptides was obtained using a voltage of 10 kV, 0.1 M phosphoric acid (pH 1.95) as electrolyte and ultraviolet detection at 185 nm. The protocol was then used to follow the metabolism of exogenous angiotensin I (ANG I) in rat lung homogenate and the separation and identification of an angiotensin peptide in human plasma. In addition to these two applications, the protocol can be used to separate and identify angiotensins and other peptides for which specific antibodies have yet to be developed.