[Spectrophotometric determination of nystatin]

New equations for spectrophotometric calculation of the concentrations of nystatin and its semiproducts in the finished drugs are presented. The results obtained with the use of these equations correlated with those of the biological assay. It was found that the difference in the standard deviations with regard to the one-point procedure for the assay of nystatin, the method of 3 equidistant wavelengths and the method of the background algebraic correction was statistically insignificant. The one-point procedure for the assay of nystatin based on measuring the solution optical density at one wavelength, i. e. 304.5 nm should be considered most handy in practice.