[Stability of rifamycin B in aqueous solutions].

Stability of rifamycin B in aqueous solutions at various values of pH and temperature was studied. It was shown that inactivation of the antibiotic in neutral and alkaline solutions proceeded according to the first order equation. In acid solutions rifamycin B was oxidized with air oxygen to form rifamycin O.

[Determination of rifamycin B activity in culture liquids and in preparations with varying degrees of purity].

A possibility of using the biological method of rifamycin B activity determination in the fermentation broth and dry preparations of various purity levels was studied. It was found that the biological method was useful only for determination of rifamycin B activity in preparations containing not less than 850 gamma/mg of the main product. When the activity of rifamycin B was determined in the fermentation broth and crude preparations containing less than 800 gamma/mg of the main product, the results of the biological assay were always higher as compared to those of spectrophotometrical estimation.

[Chromatographic control of the process of rifamycin B isolation and purification].

A method of chromatography in a thin layer of Silica Cel No. 2 was developed for rifamicin B, rifamicin complex and some admixtures. Extracts of rifamicin B in an organic solvent, aqueous buffer reextracts and dry preparations of rifamicin B were analyzed with the above method.