| Stilbene compounds normally existed in both cis- and trans- forms in nature, but only trans-isomer has antitumor, antioxidant, anti-inflammatory and other biological activities, and in the condition of light the trans-isomer can transformed into cis-isomer, which led to the lose of activities of such precursor compound of potential drug. Therefore, through spectroscopy, chromatography, capillary electrophoresis and other analytical tools to study the light-induced cis-trans isomerization of these compounds is very important for the further development and use of stilbene compounds.This dissertation mainly focused on the study of light-induced isomerization of stilbenes, including resveratrol, piceid, rhapontigenin, rhaponticin, desoxyrhaponticin and desoxyrhapontigenin using capillary electrophoresis, UV- Vis and NMR spectrum. The effects of irradiation time and wavelength of light were studied, and the stereo chemistry structure characteristics were obtaind. And the rate constant of the isomerization was also calculated. On the basis of experiment, the mechanism of reaction was discussed.On the basis of previous literatures, some original studies were carried out as follows:1. The effects of various factors on the light-induced isomerization of resveratrol and piceid were studied by CE-DAD system and UV-Vis spectrum. On the basis of experiment, the reaction conversion rate and the rate constant were calculated. Furthermore, the mechanism of reaction was preliminarily discussed.2. The determinations of trans- reactant and cis- product of the light induced isomerization of rhapontigenin and rhaponticin were performed through the capillary electrophoresis. The effects of the irradiation time and wavelength were investigated. The experiment result of CE was further verified by UV-Vis spectrum, and the stereochemistry molecular structure was confirmed by NMR.3. The effect of the complexation of P-CD and desxoyrhapontigenin on the light-induced isomerization was discussed for the first time, and studied the way of complexation, calculated the rate constant of isomerization, futher explained the experimental results.4. A selective and sensitive method was developed for simultaneous determination of ammonia and 22 aliphatic amines by micellar electrokinetic chromatography (MEKC) with laser-induced fluorescence detection (LIF) using NBD-Cl as derivatization reagent. The method was successfully applied for the determination of aliphatic amines and ammonia in environment water samples.This dissertation consists of five chapters:Chapter 1:This chapter introduced various methods for the study of chemical reaction dynamics, focus on the several common modes, developments and applications of capillary electrophoresis in the study of chemical reaction dynamics.Chapter 2:Qualitive and quantitive research of light-induced isomerization of resveratrol and piceid were performed by CE and UV- Vis spectrum. The effects of reaction conditions on the isomerization were evaluated, including the concentration of solution, wavelength of irradiation light, irradiation time, different solvents and UV absorbents. On the basis of experiment, the mechanism of reaction was preliminarily discussed. The maximum UV absorption wavelengths of methanol solution of RES, piceid and each cis-isomer were 305/285 nm and 319/291nm, respectively. The results showed that the more dilute solution was more sensitive to light; when the wavelength of light source is longer than the maximum UV absorption wavelengths of compounds, the effect on isomerization is more significant; with the irradiation time increases, the proportion of isomerization increased, when it reached the equilibrium state, the concentrations of reactants and products did not change anymore; under the irradiation of 365 nm, trans RES converted 75%, piceid converted 58%; acetone solvent with UV-absorbing chromophore inhibited the cis-trans isomerization to some extent; The UV absorbents whose maximum UV absorption wavelength longer than the maximum UV absorption wavelength of RES are also able to inhibit the isomerization of RES.Chapter 3:The determinations of trans- material and cis- product of the light induced isomerization of rhapontigenin and rhaponticin were performed through capillary zone electrophoretic. The samples after irrdiation were directly injected and analyzed by CZE-DAD, and the experiment was finishied in 3 minutes. The effects of various reaction conditions including different irradiation time, wavelength of light on the yield of isomerization were studied. And the result was further verified by UV- Vis spectrum, and the stereochemistry molecular structure were confirmed by NMR, excluded the possibility of existence of by-product.Chapter 4:Study of the light-induced isomerization of DOR and DG was performed by capillary electrophoresis. Using 30 mM borax, pH 2.5 background buffer completed the separation of the cis-product and trans-reactant within 4 minutes and the rate constant of isomerization was 0.0189 min-1. The UV-Vis spectra before and after UV irradiation were also studied. And UV spectra of the CD inclusion complex were characterized to investigate the effect ofβ-cyclodextrin (β-CD) and deoxy glycosides inclusion on the isomerization. The results showed that the cooperation with CD accelerated the process of light-induced isomerization, the reaction rate constant was 0.0268 min-1, which is bigger than the rate constant when the CD does not exist.Chapter 5:A selective and sensitive method was developed for separation and simultaneous determination of 22 aliphatic amines and ammonia by MEKC-LIF using NBD-Cl as derivatization reagent. And the detailed conditions of derivatization and separationand were discussed. The optimum deirvatization conditions were:1.5 mM NBD-Cl,30 mM borax derivatization buffer, pH 9.0,70℃, incubation time was 20 min; The optimum separation conditions were:20 mM borax separation buffer,25 mM SDS,7 mMβ-CD,10% acetonitrile and 0.5 mM urea at pH 9.70, separation voltage was 25 kV.22 aliphatic amines and ammonia were separated in a short 19 min analysis time and the relative standard deviations for migration time and peak areas were less than 0.72% and 1.73%, respectively. The method was successfully applied for the quantification of aliphatic amines and ammonia in environmental water samples, including aquarium water, lake water and the yellow river water, and the reconvenes were in the range of 90.2% to 110.8%, the result is satisfied. |
PDF Full Text Request