[Method of determining the acid-base properties of antibiotics in water-alcohol solutions]

The pH scale of aqueous-alcoholic solutions titrated with aqueous solutions of hydrochloric acid and sodium hydrate was developed. These agents are most frequently used in investigation of the acid and basic transformations of antibiotics. The use of the scale was exemplified with the study of acid and basic properties of gramicidin S containing 2 amino groups in the side chain. Calculation of the constants of protonization of the amino groups of gramicidin S showed their significant differences depending on the solvent nature.