Nuclear Magnetic Resonance Spectroscopy in Pharmaceutical Analysis

Nuclear magnetic resonance (NMR) spectroscopy is an extremely powerful tool for the detection, identification and quantification of drugs and related substances. The whole range of one-dimensional (1-D) and two-dimensional (2-D) NMR techniques is available for performing the required analyses. These NMR methods may be used for routine purposes, such as the confirmation of the identity of the drug or quantification of the amount of drug substance present in a formulation. However, the area where NMR stands out as an analytical tool is in the identification of unknown compounds such as metabolites or drug degradation products. NMR is also used for impurity profiling or determination of the drug's optical purity. Although NMR has been used for many years to analyze drugs, even the most modern spectrometers lack the sensitivity obtainable by other techniques such as mass spectrometry (MS) or high-performance liquid chromatography (HPLC). However, NMR is a nondestructive technique which provides essential structural information that cannot easily be obtained from these other methods. Recent advances in technology have allowed the interfacing of NMR instruments with other equipment such as HPLC devices to provide even more robust analytical methodology.