ABSTRACT
During the last decade, hyphenated analytical techniques have grown rapidly to solve complex analytical problems. The combination of separation technologies with spectroscopic techniques is extremely powerful in carrying out qualitative and quantitative analysis of unknown compounds in complex matrices. High-performance liquid chromatography (HPLC) is the most widely used analytical separation technique for the qualitative and quantitative determination of compounds in solution. Mass spectrometry (MS) and nuclear magnetic resonance (NMR) are the primary analytical techniques that provide structural information for the analytes. The physical connection of HPLC and MS (liquid chromatography-mass spectrometry, LC-MS) or NMR (LCNMR) increases the capability of analysts to solve structural problems of mixtures of unknown compounds. LC-MS has been the more extensively applied hyphenated technique because MS has higher sensitivity than NMR.[1-3] Recent advances in NMR, LC-NMR, and even LC-MS-NMR have enabled these techniques to become routine analytical tools in many laboratories. This article provides an overview of the LC-NMR and LC-MS-NMR techniques with a description of their limitations, together with an example of LC-MS-NMR to illustrate the data generated by these hyphenated techniques. This article is not meant to imply that LC-MS-NMR will replace LC-MS, LC-NMR, or NMR techniques for structural elucidation of compounds. LC-MS-NMR, together with LC-MS, LC-NMR, and NMR, are techniques that should be available and applied to appropriate cases based on their advantages and limitations.
