Fluorometric Analysis Of Vanillic Acid And Caffeic Acid In Traditional Chinese Medicine

In this thesis,fluorescence properties of vanillic acid(VA),caffeic acid(CA)and ethyl caffeate(EC)are studied.Fluorometric methods for determination of VA in Rhizoma picrorhizae(RP,Huhuanglian),in Fattening Baby Pill(FBP,Fei'er Wan)and in Huanglian Yanggan Pill(HYP,Huanglian Yanggan Wan),and CA in Dandelion(Pugongying),are investigated.In the experiment,fluorescence information of standard solution and sample solution are obtained by three-dimensional fluorescence technology,and the possible interference in the sample is preliminarily judged by comparing the consistency of fluorescence spectra,then fluorospectrophotometric method and three-dimensional fluorescence coupled with second-order correction method based on the alternating trilinear decomposition algorithm(ATLD)are used respectively to process spectral data in order to select the appropriate method.Three parts were included in this thesis:1.Fluorescence property of VA is studied.The native fluorescence of VA is very weak,but a sensitized fluorescence is produced when Al Cl3 is added into the VA aqueous solution.The fluorescence is stable under weak acidic condition,with maximum excitation and emission wavelengths located at 260 nm and 344 nm,respectively.The effects of experimental conditions on the sensitized fluorescence are investigated.Using L-tryptophan as a reference,fluorescence quantum yield of VA-Al(?)complex is measured to be 0.21,indicating that the complex is a strong fluorescence substance.2.Based on the fluorescence properties of VA,the contents of VA in RP,in FBP and in HYP are determined by fluorospectrophotometric method.The contents of VA are determined to be 0.434% in RP,0.106% in FBP,and 0.0344% in HYP.In the meantime,by using three-dimensional fluorescence coupled with second-order correction method,the contents of VA are detected to be 0.373% in RP,0.101% in FBP,and 0.0303% in HYP.By comparison,the results of the two methods are basically the same for VA in FBP,but different for VA in RP and in HYP,indicating that three-dimensional fluorescence coupled with second-order correction method has some ability to distinguish the interference of coexisting components.3.The fluorescence properties of CA and EC are studied.The effect of light on the fluorescence intensity of CA is investigated.It is found that the fluorescence of caffeic acid is enhanced by light irradiation.Using fluorospectrophotometric method and three-dimensional fluorescence coupled with second-order correction method,the content of CA in Dandelion is determined to be 0.0232% and 0.0240%,respectively.The two results are basically consistent.In this section,the feasibility of detection of CA and EC in the mixed solution by using three-dimensional fluorescence coupled with second-order correction method is also explored,and a meaningfull result is obtained.