Certification of Reference Standards in Pharmacy: Mass Balance Method

Approaches to certification of substances as reference standards (RSs) by the mass-balance method and the restrictions that must be considered when using this method are considered. Formulas for estimating the uncertainty of certified values are presented. Also, formulas missing from the literature are given to assess a) the uncertainty in the contents of organic impurities obtained by normalization of peak areas (heights) with correction factors and b) the uncertainty in the detection limits of the organic impurities. Recommendations for correct certification of reference standards by the mass-balance method are provided.