ABSTRACT
Typically, most chemists think of infrared (IR) spectroscopy as the only form of vibrational analysis for a molecular entity. In this framework, IR is routinely used as an identification assay for various intermediates and final bulk drug substance, and also as a quantitative technique for solution-phase studies. Full vibrational analysis of a molecule must also include Raman spectroscopy. Although IR and Raman spectroscopy are complementary techniques, widespread use of the Raman technique in pharmaceutical investigations has been limited. Before the advent of Fourier transform techniques and lasers, experimental difficulties tended to limit the use of Raman spectroscopy. However, over the last 20 years a renaissance of the Raman technique has been seen, due mainly to instrumentation development.
