Industry Insights: The Case For Raman Spectroscopy

Bioresearch Online had the opportunity to speak with three spectroscopy experts to uncover the trends and challenges associated with the growing use of Raman spectroscopy (RS).

What specific type of information does Raman spectroscopy (RS) give?

Art Hamfeldt, Delta Nu:  RS, like some other well-known spectrophotometric techniques (e.g. Mid-Infrared Spectroscopy), provides qualitative information about the chemical identity of a compound. The Raman spectrum is unique for a given compound (except in the case of chirality) and can be utilized as a compendial ID test, as well as for structural elucidation (per USP <1120>). RS provides quantitative information as well, thus also making it a good choice for gathering reaction monitoring information and implementation in PAT/QbD.

Raman, being a spectrographic technique, involves electromagnetism exciting the electrons in a bond with a photon and observing the behavior the interaction of that photon with the bond.  Raman Spectroscopy (RS) specifically uses light, from UV to NIR, and observes the shift in wavelength from the original. A photon entering a bond can be absorbed or returned as is (Rayleigh) or the photon can be absorbed and returned with more (anti-Stokes) or less energy (Stokes). The second interaction is used in Raman Spectroscopy as the shifts observed in wavelength are directly propositional to length and number of those bonds in a molecule.  Raman takes advantage of the fact that the ratio of observed bonds are fixed for a given molecule, allowing for identification.