Fluorescence Property And Analysis Of Syringic Acid, Sinapic Acid And Catechin In Chinese Herbal Medicine

Fluorescence spectra of syringic acid and sinapic acid, active components of Chineseherbal medicine, were studied in this thesis, and influences of experimental conditions onfluorescence spectra were investigated. High performance liquid chromatography (HPLC)methods were established for the determination of syringic acid in Leonuri Herba (Yimucaoin Chinese) and sinapic acid in Sinapis Semen (Jiezi in Chinese). Three-dimensional (3D)fluorescence spectra of catechin were also investigated, and a fluorimetric method fordetermination of catechin in Catechu (Ercha in Chinese) was established.Three parts were included in this thesis:1. Fluorescent properties of syringic acid were studied. Using L-Trp as a reference,Fluorescence quantum yields of syringic acid in water and in alkaline solutions weremeasured to be0.014and0.009, respectively. Molar fluorescence coefficients of syringic acidin water and in alkaline solutions were measured to be5.03×106(L/mol) and9.24×106(L/mol),respectively. The ionization constants of syringic acid were determined to be pKa1=4.33andpKa2=9.45, by a UV absorption method. Due to the interference of coexistent components,the content of syringic acid in Chinese herbal medicine Caryophylli Flos (Dingxiang inChinese) and in Yimucao was not determined by fluorimetric method and by thin layerchromatography (TLC) scanning method. An HPLC method was developed for thedetermination of syringic acid in a Leonuri Herba sample, and the result was3.33×10-4%.2. Fluorescent properties of sinapic acid were studied. Fluorescence quantum yield ofsinapic acid was measured to be0.009, using quinine sulfate as a reference. Influence of pHon fluorescence spectra of sinapic acid-CTAB system was investigated. Molar fluorescencecoefficient of sinapic acid in water was measured to be8.97×105(L/mol). Since theinterference of coexistent components with the fluorescence of sinapic acid and the instabilityof sinapic acid on thin layer plate, content of sinapic acid in Jiezi can not be determined byfluorimetric method and by TLC scanning method. An HPLC method was developed for thedetermination of sinapic acid in a Jiezi sample, and the result was0.0603%.3. Molar fluorescence coefficient of catechins in water was measured to be3.83×107(L/mol). A fluorimetric method was proposed for the determination of catechin in an Ercha sample, and the result was25.95%.