| Gallic acid (GA) is a kind of polyphenolic compounds in nature, and widely distributed in medicine herbs, such as Rhus Chinensis Mill., Radix Sanguisorbae, et al. GA is an important organic fine chemical material, it is mainly used to produce ink, dye and medicine, and is applied in daily chemicals, leather, food, organic synthesis, et al. The last century, products with GA as functional ingredient are popular in the international market, which greatly promoted the domestic research and development of GA. Ellagic acid (EA) is one of natural polyphenol compounds, belongs to the two poly-derivatives of gallic acid, and widely distributed in Pomegranate, Terminalia Chebula Retz. and other medicine herbs. Due to excellent antioxidant property and whitening effect, EA has been widely used in food, medicine, cosmetics.This thesis made a systematic and comprehensive study on chromatographic separation and determination, properties of solutions of GA and EA, preparation and identification of EA-Ca complex.Our main work as follows:1. Determination of GA and EA in18kinds of medicine herbs by HPLC analysisIn this chapter, optimum mobile phase conditions of HPLC separation and determination of GA and EA were discussed by changes of mobile phase ratio and concentration of phosphoric acid aqueous; And content of GA and EA in18kinds of medicine herbs were determined. The results showed that optimum chromatographic separation condition of GA and EA was Gemini5u C18110A (250mm×4.6mm,5μm) chromatographic column, column temperature35℃, a flow rate of1mL/min, UV detection wavelength of254nm, with mobile phase of methanol:water (0.3%phosphoric acid)=55:45(V:V); GA and EA were completely separated in10min. Determination results of18kinds of medicine herbs showed that GA was only detected in4medicine herbs, the highest content of GA was up to280.4mg/g in Rhus Chinensis Mill.. EA was only found to be contained in6medicine herbs, the highest content of GA was up to was up to162.2mg/g in Pomegranate. Both GA and EA were simultaneously found in4medicine herbs. Both GA and EA were not detected in4medicine herbs. The HPLC method established by this experiment with high precision, good repeatability, high recovery, stable measurement result, and has the advantages of simple operation and rapid.2. Studies on properties of GA and EA solutionsIn this chapter, influences of pH value, metal ions, EDTA, lights, temperatures on GA and EA were discussed through ultraviolet spectrophotometry. The results showed that under different acidic conditions, maximum absorption wavelength of GA and EA solutions did not significantly change, but under alkaline conditions, with the increase of pH value of solution, different levels of dissociation of carboxyl, hydroxyl of GA, and hydrolysis of lactone bond, dissociation of phenolic hydroxyl of EA affected their characteristic absorption in the ultraviolet region. Monovalent metal ion and divalent metal ion did not have a great effect on the maximum absorption wavelength and its corresponding absorbance value of GA and EA, but trivalent metal ion significantly changed their maximum absorption wavelength and corresponding maximum absorbance values. EDTA with low concentration did not have obvious effects on GA and EA, but increasing of concentration of EDTA could significantly reduce the absorbance value of EA. After placed5h, GA and EA had less degradation under the condition of indoor lighting, and had obvious degradation under the condition of outdoor lighting. GA and EA had thermal stablity.3. Preparation and characterization of EA-Ca complexIn this chapter, EA and calcium chloride were used as raw material to prepare EA-Ca complex. The complex was dark green solid with stable physical properties, and poorly dissolved in most organic solvents. Element analysis result showed that molecular formula of complex was Ca(C14H9O10)2·2H2O; Infrared absorption spectrum analysis showed that compared with EA, main absorption peaks of complex had obvious displacement, and their relative intensity changed; vibration peak of3421 cm-1, multiple broad peak among3000～2500cm-1interval and707,667and551cm-1respectively indicated that there was water, carboxyl, and O-Ca-O bond in complex molecular. TG, DSC and X-ray diffraction analysis showed that various properties of EA-Ca complex were different from EA, which further proved EA and calcium ion formed complex. |
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