Pharmaceutical process applications of Raman spectroscopy

摘要

In the past decade Raman spectroscopy has moved out of the shadow of infrared spectroscopy and has become a routine analytical tool and is finding value in pharmaceutical process applications. Raman spectroscopy, like infrared spectroscopy, can identify and quantify chemicals by their vibrational modes. Raman spectroscopy offers two important advantages for process measurements. First, communication grade fiber optics can be used to transmit and collect light to and from a sample probe, allowing considerable flexibility in probe designs. Second, Raman scattering responds linearly to concentration, and a path length does not have to be defined as in infrared spectroscopy. However, process Raman measurements, such as continuous monitoring or raw materials identification, have been slow to develop due to instability of the wavenumber axis. To overcome this difficulty, just as dispersive infrared spectrometers have been replaced by Fourier transform infrared spectrometers, we have developed an industrial hardened Fourier transform Raman spectrometer. Furthermore, we have increased sensitivity by 30 times by employing an Si detector instead of an InGaAs detector. Here we present the abilities of this hybrid Raman spectrometer to address a number of pharmaceutical applications, including identifying raw materials in less than one minute using spectral library matching, analyzing blended materials, and determining polymorphism.