COMPARATIVE-ANALYSIS OF SOMATOSTATIN ANALOG PEPTIDES BY CAPILLARY ELECTROPHORESIS AND MICELLAR ELECTROKINETIC CHROMATOGRAPHY

Capillary electrophoresis (CE) and micellar electrokinetic chromatogra phy (MEKC) methods, utilizing uncoated silica capillary and triethyl a mmonium phosphate or sodium berate buffers in the pH range of 2.25-11. 0, containing sodium dodecyl sulfate (SDS) (0-100 mM) for analysis of somatostatin-analog peptides were developed. The method presented here was compared with the reversed-phase high performance liquid chromato graphic (RP-HPLC) and CE methods developed for analysis of peptides. T he peptides investigated in this work can be separated by CE on the ba sis of their electrophoretic mobility in aqueous buffer of low pH valu e (pH 2.25) or by MEKC on the basis of their hydrophobicity in SDS con taining buffer of high pH value (pH 11.0). Optimal MEKC separation of the investigated peptides has been achieved at pH 11.0 in an Na-borate buffer containing 100 mM SDS. CE at pH 2.25 proved insensitive to the hydrophobicity of the peptides investigated. By contrast, results obt ained with MEKC at pH 11.0 proved to be anologous to those obtained by RP-HPLC, with highly hydrophobic peptides - migrating slower than pep tides without hydrophobic moieties.