Investigation On Liquid Chromatography Electrochemistry Of Phenolic Compounds And β₂-Agonists

Electrochemical detector with the unique characters of high sensitivity, high selectivity, wide linear range, simple structure and small dead volumn, has been widely used. In this thesis, the high performance liquid chromatography - electrochemical detector (HPLC - ECD) method with liquid - liquid extraction or off-line pre-column reaction is established to detect the six kinds of phenolic compounds in Chinese herbal medicine and threeβ₂-agonists. The study has a certain of significances in broadening the application range of ECD. This thesis consists of four chapters. The works are as follows:The determination method of protocatechuic aldehyde, ferulic acid and baicalin in Tongmai granules is established by RP - HPLC - ECD. The results show that the recoveries of protocatechuic aldehyde, ferulic acid and baicalin in Tongmai granules are 97.4%, 98.7% and 97.9% respectively, and relative standard deviations (RSDs, n=3) are 0.8%, 2.3% and 2.9% respectively. The method provides the scientific basis for the quality control of Tongmai granules.A new method of HPLC - ECD using off-line pre-column reaction is established for the investigation of DPPH radical scavenging capacity of protocatechuic acid, chlorogenic acid, caffeic acid and ferulic acid, and the method is futher applied to investigate DPPH radical scavenging capacity of Honeysuckle and Chuanxiong. The results show that the 50% inhibition concentration (IC50) order of DPPH radical scavenging of four compounds is caffeic acid > chlorogenic acid > protocatechuic acid > ferulic acid, and the recoveries of four compounds are in the range of 95.3% to 100.1% (RSD≤3.2%). The method can be utilized for identifying the components of the Chinese herbal medicine with antioxidation function.A new method of HPLC - ECD using the two extractions is established for simultaneous separation and determination of two misusedβ₂-agonists (salbutamol sulfate and clenbuterol hydrochloride) in swine feed. The results show that calibration curves show good linearity relationship (r≥0.9993), and the extraction recoveries of two compounds are in the range of 75.1% to 95.9% (RSD≤1.8%). Compared with HPLC - DAD, HPLC - ECD is more sensitive.Two new methods of HPLC - ECD are established for the determination of the two misusedβ₂-agonists. They are as follows:HPLC - ECD technic is applied to detect the contents of salbutamol sulfate and formoterol fumarate in commercial tablets. The results show that the linear range of two compounds is 9.44×10^-1～3.38×10(r =0.9996) and 3.12×10^-1～5.00×10μg·mL^-1 (r =0.9995), and the recoveries are 99.0～107.8% (RSD≤4.6%). The method can be used for the determination of salbutamol sulfate and formoterol fumarate in commercial tablets.HPLC - ECD technic with liquid - liquid extraction is applied to determine formoterol fumarate in analog plasma of rabbit. The results show that the linear range of formoterol fumarate is 47～2500 ng·mL^-1 (r =0.9999), the extraction recoveries are 77.8～80.1%, and the method recoveries are 96.2～106.0% (RSD≤1.9%). The method is expected for the analysis of drug metabolism in animals.