SUMMARY
The study of validation parameters of the quantitative determination method of riboflavin by specific absorbance and their assessment have been conducted in order to standardize procedures for analysis by the specific absorbance and the stage-by-stage control of correctness of the results obtained during the validation experiment. According to the requirements of the State Pharmacopoeia of Ukraine (SPhU) the qualification of the spectrophotometer has been performed. The control of the cells (ddif = 0.002), absorbance accuracy, absorbance convergence with removing the cells (RSD0 0.0007% = 0.25%), as well as the study of the limit of stray light (absorbance of the solution at the wavelength of 198 nm is 2.56 = 2.0, which meets the requirements of SphU) have been carried out. Characteristics and acceptance criteria of the assay method for riboflavin such as the nominal concentration of the substance in solution by the method, the nominal absorbance and requirements for its minimum value, the maximum uncertainty of the analysis procedure have been theoretically calculated. The linearity parameter has been studied at 9 points. The linear dependence plot has been constructed in the normalized coordinates. The values of b, sb, a, sa, RSD0 and r calculated comply with the requirements to parameters of the linear dependence. When studying the parameter of accuracy the systematic error is d = 0.72%, which meets d = 1.00%. According to the results of the convergence study the relative confidence interval ?As = 0.83% does not exceed the critical value for convergence of the results ?As = 0.96%. The validation parameters of the method meet the requirements of the SPhU and are characterized by qualitative analytical indicators.