ABSTRACT
The first measurements of the infrared absorptions of molecules occurred in the 1880s and the early spectroscopists performing these analyses recognized the potential of using this method to identify the organic compounds. These measurements were made using primitive devices, however, with analysts manually recording the absorption of each wavelength. This tedious process required several hours for each sample and infrared spectroscopy remained an esoteric research tool for several decades. From an analytical chemistry perspective, infrared spectroscopy has few peers in terms of its wide applicability and versatility. The forensic drug chemist, however, uses infrared spectroscopy because it can be used to distinguish among closely related compounds, such as positional isomers, geometric isomers, diastereomers, and so forth. It is for organic compounds that the attributes normally associated with infrared spectroscopy, namely its ability to provide functional group information and to permit differentiation between closely-related structures, are most evident.
