3 Separation methods for
impurities
According to the impurities source, it is a big challenge to completely
remove the impurities in the medicine. In addition, the analysis method
of impurities not only needs detect the known impurities of the drug,
but also needs effectively detect the potential impurities in the
impurity spectrum concept. Therefore, choosing appropriate analytical
methods that accurately distinguish and quantify impurities is a key
link in the quality control of drugs. Some detectors can detect
impurities without separation. For example, quantitative Nuclear
Magnetic Resonance Spectroscopy (qNMR) 34 has been
described completely in the qualitative and quantitative methods
section. However, it is not feasible for some detectors to directly
perform qualitative and quantitative analysis of impurities in drugs.
Through separation technology, a single compound can be obtained before
detection to ensure the accuracy and authenticity of the detection
result. Some separation methods are shown in Table 1.
3.1 Liquid
Chromatography