What are standards and reference substances? standard
Reference substance and standard substance are two different concepts, which are clearly defined in the Chinese Pharmacopoeia: control strain refers to the reference substance used for identification, inspection, content determination and calibration of the performance of the verification instrument, while standard strain refers to the reference substance used for biological assay, antibiotics or biological drugs.
The two concepts are often confused in the literature, believing that the reference substance is the standard substance, and it is only two formulations of one substance. The reason for the error may be that some drugs have bothreference substance, and there are standards. For example, when measured by microbiological methodCefkroWhen potency is used, cefcro standard is used, and when it is determined by HPLC or UV spectrophotometer, a reference substance is used; when phenacetin is used as a melting point calibration substance, a melting point standard is used, and when the content is determined, a reference substance is used. Even standards and reference substances of the same substance may have different specifications, calibration methods, and uses.
The mixing of reference substances or standards, that is, the use of reference substances or standards for content determination that is not their calibration method, is a problem that often occurs in drug inspection but has not attracted attention. Although the content of different calibration methods of the same batch of reference substances has a good correlation, the national standard product network collates and provides them but not exactly the same, and sometimes the difference can be very large. For example, the cefuroxime ester reference substance provided by the British company Glaxo, HPLC calibration is 96.9% for content determination; UV is 98.8% for dissolution determination. Although the Chinese Pharmacopoeia generally stipulates that the reference substances issued by the Ministry of Health are only used for the analytical methods specified in the text. But because:
(1) The instructions for use of reference substances provided by the Ministry of Health are not detailed enough, and most of them do not have quality requirements and calibration methods for reference substances.
(2) Lack of awareness of the correct use of reference substances or standards;
(3) It is extremely difficult to find corresponding reference substances in daily scientific research.
(4) In the text of the Chinese Pharmacopoeia, there is also the problem of mixing reference substances. For example, the standard or reference substance used for content determination is often used for dissolution inspection, and the content determination method is different from the dissolution analysis method, so it is very easy to cause mixing.
