Capillary Electrophoretic Analysis of Somatostatin Analog Peptides. Effect of Organic Solvents as Buffer Modifiers

Capillary electrophoretic (CE) method utilizing triethylammonium phosphate/organic modifier solvents as CE buffer was developed for analysis of new proprietary Somatostatin analog peptides synthetized in our laboratory. Acetonitrile, methanol, ethanol and i-propanol were applied as organic modifiers. Applicability of the systems in the analysis of Somatostatin analog peptides was evaluated and optimum conditions of the separation were determined. The effects of the organic solvents on the migration times of the S-analog peptides, elution order and selectivity in the CE systems were investigated. The migration time, elution order and selectivity can be influenced modifying the composition of the electrophoretic buffer with organic solvents. Applying different organic solvents as modifiers the elution order of the peptides can be changed in different ways. The effect of the alcohols on the CE migration time of the peptides is quite opposite to that of the acetonitrile. The degree of the effect of the alcohols at a given concentration depends on the nature of the alcohol: the longer the carbon chain of the alcohol the greater the increase of the CE migration time of the peptide comparing to the migration time obtained in buffer not containing organic solvents.