Correction Factors in Formulas for Calculating Impurity Contents: Essence and Determination Methods and Their Limitations

Resumo

Formulas for calculating relative response factors (RRFs) and correction factors (Fs) of impurities and those necessary for understanding the essence of RRFs and Fs are presented. The main methods for determining Fs and their limitations (conditions necessary for correct determination of RRFs and Fs) are considered. These limitations do not appear in the European and US pharmacopoeias although they must be considered to determine the correct Fs. Examples and recommendations are given for reliable determination and correct use of the Fs.