Study On Difference Between Epidermis, Phloem And Xylem Of Radix Ginseng With Molecular Spectroscopy And High Performance Liquid Chromatography

Ginseng as a valuable Traditional Chinese Medicine, its research is a hot field. HPLC is one of the most popular methods in the research, but it will causes irreversible damage of samples and needs long analytical time normally. Molecular spectroscopy, such as IR and NIR that can supply nondestructive analysis can offset insufficiency of HPLC. A method has been established to study differences between parts of a ginseng including epidermis, phloem and xylem using infrared spectroscopy, near-infrared spectroscopy and HPLC.Infrared spectra of ginseng epidermis, phloem and xylem are clear different. The epidermis contains very high characteristic peaks of volatile oil (peaks 2920 cm-1 and 1736 cm-1), but do not contains characteristic peak of polysaccharide (peak 925.7 cm-1). PCA result shows that epidermis clearly separated from phloem and xylem, and some dots of phloem and xylem are mixed.Particle size and thickness of sample loaded are important interference factors for determination of near infrared spectroscopy.200 mesh of sample granularity was chosen, according to experimental comparison. Sample thickness must be over 1 cm normally to record stable and reliable spectra. In the study, large numbers of samples from different positions of ginseng were collected each containing small volume. A small volume sample holder (1-2mm thickness sample) was developed for the measurements of ginseng samples.The analysis results of near infrared spectra also show that the epidermis, phloem and xylem parts of ginseng root are obvious different according to the NIR spectra, even spectra measured at different positions from top to bottom of epidermis, phloem and xylem show gradually changes.Operation conditions of HPLC analysis for ginseng samples were established and the samples from the epidermis, phloem and xylem parts were analyzed. The classification results of the three parts due to HPLC data are similar with those of IR and NIR data. The results indicate that IR and NIR spectroscopy can replace HPLC to analyze the differences between different parts of epidermis, phloem and xylem of ginseng.