The most widely used analytical separation technique for the qualitative and quantitative determination of chemical mixtures in solution in the pharmaceutical industry is high-performance liquid chromatography (HPLC). However, conventional detectors used to monitor the separation, such as UV, refractive index, fluorescence, and radioactive detectors, provide limited information on the molecular structure of the components of the mixture. Mass spectrometry (MS) and nuclear magnetic resonance (NMR) are the primary analytical techniques that provide structural information on the analytes. NMR is widely recognized as one of the most important methods of structural elucidation, but it becomes cumbersome for the analysis of. | 20 LC-NMR OVERVIEW AND PHARMACEUTICAL APPLICATIONS Maria Victoria Silva Elipe INTRODUCTION The most widely used analytical separation technique for the qualitative and quantitative determination of chemical mixtures in solution in the pharmaceutical industry is high-performance liquid chromatography HPLC . However conventional detectors used to monitor the separation such as UV refractive index fluorescence and radioactive detectors provide limited information on the molecular structure of the components of the mixture. Mass spectrometry MS and nuclear magnetic resonance NMR are the primary analytical techniques that provide structural information on the analytes. NMR is widely recognized as one of the most important methods of structural elucidation but it becomes cumbersome for the analysis of complex mixtures that require time-consuming sample purification before the NMR analysis. During the last two decades hyphenated analytical techniques have grown rapidly and have been applied successfully to many complex analytical problems in the pharmaceutical industry. The combination of separation technologies with spectroscopic techniques is extremely powerful in carrying out qualitative and quantitative analysis of unknown compounds in complex matrices in all the stages of drug discovery development production and manufacturing in the pharmaceutical industry. The HPLC or LC and MS LC-MS or NMR LC-NMR interface increases the capability of solving This chapter is an update reprinted from the reference 40 reprinted with permission from Elsevier copyright 2003. HPLC for Pharmaceutical Scientists Edited by Yuri Kazakevich and Rosario LoBrutto Copyright 2007 by John Wiley Sons Inc. 901 902 LC-NMR OVERVIEW AND PHARMACEUTICAL APPLICATIONS structural problems of mixtures of unknown compounds. LC-MS has been one of the most extensively applied hyphenated techniques for complex mixtures because MS is more compatible with HPLC and has higher sensitivity than NMR 1-3 . Recent
