Abstract:
The classical analytical methods of extraction, separation, isolation and structure elucidation of natural substances, as the carotenoid stereoisomers, the flavonoid glycosyl-derivatives and the tocopherols are very time-consuming considering the constantly growing number of samples. Besides, analytical measurements of light and oxygen-sensitive substances without producing artefacts are not possible on this conventional way. Therefore, identification and structural information of these unstable biological materials are only available with the help of combined separation-identification methods. The direct coupling of the high pressure liquid chromatography (HPLC) with mass spectrometry (MS) or nuclear magnetic resonance spectroscopy (NMR) is essential for a fast and efficient handling of modern analytical problems. By combining the on-line HPLC-MS with HPLC-NMR coupling a complete structure elucidation of biological samples in the ng-range is possible.