Footnotes Source of Support: Nil Conflict of Interest: None declared.
Hyphenated techniques combine chromatographic and spectral methods to exploit the advantages of both. Chromatography produces pure or nearly pure fractions of chemical components in a mixture. Spectroscopy produces selective information Romidepsin mechanism for identification using standards or library spectra. A couple of decades ago, Hirschfeld introduced the term ��hyphenation�� to refer to the on-line combination of a separation technique and one or more spectroscopic detection techniques. This technique, developed from a marriage of a separation technique and a spectroscopic detection technique, is nowadays known as hyphenated technique [Figure 1]. Figure 1 Hyphenated technique In recent years, hyphenated techniques have received ever-increasing attention as the principal means to solve complex analytical problems.
The power of combining separation technologies with spectroscopic techniques has been demonstrated over the years for both quantitative and qualitative analysis of unknown compounds in complex natural product extracts or fractions. To obtain structural information leading to the identification of the compounds present in a crude sample, liquid chromatography (LC), usually a high-performance liquid chromatography (HPLC), gas chromatography (GC), or capillary electrophoresis (CE) is linked to spectroscopic detection techniques, e.g., Fourier-transform infrared (FTIR), photodiode array (PDA) UV�Cvis absorbance or fluorescence emission, mass spectroscopy (MS), and nuclear magnetic resonance spectroscopy (NMR), resulting in the introduction of various modern hyphenated techniques, e.
g., CE-MS, GC-MS, LC-MS, and LC-NMR. HPLC is the most widely used analytical separation technique for the qualitative and quantitative determination of compounds in natural product extracts. The physical connection of HPLC and MS or NMR has increased the capability of solving structural problems of complex natural products. Because of the greater sensitivity, LC-MS has been more extensively used than LC-NMR. The hyphenation does not always have to be between two techniques; the coupling of separation and detection techniques can involve more than one separation or detection techniques, e.g., LC-PDA-MS, LC-MS-MS, LC-NMR-MS, LCPDA-NMR-MS, and the like.
Where trace analysis is vital, and the analyte enrichment is essential, on-line coupling Anacetrapib with solid-phase extraction (SPE), solid-phase microextraction or large volume injection (LVI) can be incorporated to build in a more powerful integrated system, e.g., SPE-LC-MS or LVI-GC-MS. The two key elements in natural product research are the isolation and purification of compounds present in crude extracts or fractions obtained from various natural sources, and the unambiguous identification of the isolated compounds.