As the impurity removal has been given huge emphasis by regulatory authorities, several isolation and identification techniques have been suggested based on the type of impurities.
Usually, non-chromatographic and chromatographic techniques are being used for the isolation of impurities before its characterization. According to the impurity guidelines by ICH in new Active pharmaceutical ingredient , impurities below 0.1% level is usually not considered to be necessary, unless they are likely to be abnormally potent or toxic. Hence, it is very important to analyze them properly.
Since titrations are simple and accurate, these methods are used for a large proportion of the content determinations. Development of functional group analysis has resulted to beneficial in kinetic measurements which are used to establish reaction rates. The advantages of this technique are:-
- high precision
- Time and labor saving
- No need of using reference standards
Active pharmaceutical ingredient (APIs) in pharmaceuticals can be exactly estimated by ion chromatography. This can be used for separation of structurally similar antibiotics. Following Chromatographic techniques are generally used:-
- Thin layer chromatography
- High performance thin layer chromatography
- High-performance liquid chromatography (HPLC)
- Gas chromatography
They are based on absorption capacity of certain wavelengths by Active pharmaceutical ingredient or impurities. . Following Spectroscopic techniques are generally used:-
- Near infrared spectroscopy (NIRS)
- Nuclear magnetic resonance spectroscopy (NMR)
- Fluorimetry and phosphorimetry
The use of electrochemical methods in analysis of Active pharmaceutical ingredient has increased greatly over the last few years. Following Electrochemical techniques are generally used:-
This is an important method emerging lately in analysis of drugs. It is based on the separation of charged particles through a small capillary under the influence of an electric field. They are quicker and can be performed more effectively.