Certification of Pharmaceutical Substances as In-House Primary Standards (Review)

The question of certification of a pharmaceutical substance (DR) as a standard arises quite often during the development, validation, and use of analytical methods in laboratories. At present, R&D and QC laboratories are more and more widely using the mass-balance method for certifying in-house primary standards (IPSs). At the same time, it has pitfalls that need to be taken into account. In this review, the features of DR certification as IPSs by the mass-balance method or differential scanning calorimetry (DSC) are considered. The necessary calculation formulas, explanations, and recommendations are provided. It is emphasized that the certification of DRs as IPSs is an easier procedure than it might initially appear. When using the mass-balance method, the actions resemble the incoming control of several samples of a substance without biological indicators. IPSs are more accurate than secondary standards. They can also be used for quality control of medicines and for incoming control of parent substances (when no pharmacopoeial standards are available).