Infrared absorption spectroscopy

Abstract

The applications of infrared (IR) absorption spectroscopy are one of the most fun- damental and useful spectroscopic techniques available in the arsenal of a pharmaceutical scientist. Typically, when most investigator scientists think of vibrational spectroscopy, studies in the IR region of the spectrum come to mind, owing to the commercial availability of spectrophotometers, the common understanding of the technique, the ease of spectral interpretation with the aid of correlation tables, and the widespread reference to the technique in pharmaceutically based regulatory guidance documents. Within this frame- work, the IR spectroscopy is routinely used as an identification assay method for various intermediate compounds, active pharmaceutical ingredients, excipi- ents, and formulated drug products, and the methodology can also be developed as a quantitative technique for any of these.