Analysing the quality of drugs
Vibrational spectroscopy, which is a technique for revealing the chemical and physical properties of molecules, is a precious tool in the pharmaceutical sector. Researchers at the Analytical Chemistry Laboratory of the University of Liege who specialise in this area of research, regularly collaborate with pharmaceutical companies to check their raw materials, finished products and processes.
Vibrating the molecules in order to expose them
There are three main techniques of vibrational spectroscopy known as mid-infrared (MIR), near-infrared (NIR) and Raman. In the context Process Analytical Technology (PAT), the first is used for more specific applications and the two others are often considered as being complementary. “Near-infrared spectroscopy is a technique that is very well-developed while that based on Raman scattering that is being currently developed offers advantages with regard to the interpretation of the signals obtained. It is also a very promising technique in the biotechnology sector”, explains Eric Ziemons. Without going into the details of these different techniques, all three are based on the same principle: causing the vibration of the molecules in a sample to vibrate and gathering information on the chemical bonds of the molecules that it is composed of. “In this way we obtain two types of information: chemical and also physical characteristics (crystalline structure, size of the particles, hardness of a tablet)”, continues the specialist. “These techniques present important advantages with regard to traditional methods such as liquid chromatography. While analysis of a drug by the latter method takes several minutes, analysis by vibrational spectroscopy only takes 5 to 10 seconds and does not require preparation of the sample beforehand. Combined with imaging, it makes it possible to precisely map one or other compounds of the pharmaceutical matrix”, indicates Eric Ziemons. Another non-negligible advantage, particularly in the context of following procedures or in the fight against drug counterfeiting: vibrational spectroscopy is a non-destructive method. The sample analysed can therefore be recovered to be subjected to other analyses.