Drug analysis focuses on the determination of content and related substances, followed by other impurity inspection and identification items. Most of the impurities are inorganic salts, ionic impurities and elemental impurities, and the determination and inspection of these impurities are generally introduced in the process, which is generally not directly related to the drug structure. It can be identified from the specific functional groups and ions of drugs (such as lactate identification, sodium salt identification, specific reactions of some functional groups, etc.). ). Other items such as residual solvent, moisture, residue on ignition, sterility and heat source inspection, preparation inspection, etc. have nothing to do with the drug structure.
As far as content and related substances are concerned, the determination of content and related substances by high performance liquid chromatography has become popular. High-performance liquid chromatography (HPLC) is a method to achieve separation through the structural differences between the main components of drugs and their related substances or starting materials (this difference mainly comes from factors such as polarity, chirality, affinity for stationary phases, etc.). ), and through the optical characteristics of drugs to detect (for ultraviolet light, substances that do not absorb in the ultraviolet region can be detected by universal detector or even mass spectrometry). Therefore, the column type, detector type, general composition of streamline and other factors can be preliminarily determined from the structure, but the specific analysis method needs specific experiments to determine.