Study On Phenolic Compounds In Honey By Chromatograph Analysis And Electrospray Mass Spectrometry

In this thesis,high performance liquid chromatography with electrochemical detection (HPLC-ECD) and electrospray ionization tandem mass spectrometry(HPLC-ESI-MS) are used in the analysis of phenolic compounds in Chinese honey,and quantum chemistrycalculation method is applied to analyze the fragmentation pathways of four flavonoid compounds.The thesis consists of five chapters,the main contributions are summarized and presented as follows:1.A simple and rapid method for the determination of phenol and thymol in honey by high performance liquid chromatography using combined electrochemical detection with diode array detection(HPLC-ECD-DAD) has been established.The limit of detections(LODs) for phenol and thymol are determined to be 2.0 ng/g and 12.5 ng/g,respectively.The sensitivity detected by ECD is 400-800 folds higher than that obtained by DAD.The method simplifies the sample treatment,decreases the determination time,reduces the error origins and makes samples be analyzed directly without enrichment.2.The HPLC-ECD method for the determination of four kinds of phenolic compounds (caffeic acid,p-coumaric acid,ferulic acid,hesperetin) in Chinese citrus honey by testing the chromatographic column,mobile phase,potential and separation condition has been founded. The experiment results indicate that the four phenolic compounds show good linearity (r＞0.9993),with the recoveries ranging from 98.9%to 100.3%and RSDs from 1.1%to 1.8%. This method is more simple,rapid,accurate and sensitive compared with the traditional methods.3.The rapid and accurate method for the simultaneous separation and determination of eight phenolic compounds,including gallic acid,caffeic acid,p-coumaric acid,ferulic acid, myricetin,quercetin,kaempferol and galangin in Chinese sunflower honey by HPLC-ECD-DAD has been established.The detection limits of the eight phenolic compounds by ECD range from 1.0×10^-3μg/mL to 2.9×10^-3μg/mL,much lower than that by DAD(3.1×10^-2 μg/mL to 9.7×10^-2μg/mL).4.The fragmentations of apigenin,chrysin,galangin and kaempferol are analyzed by ESI-MS and Gaussian program on the basis of Density Functional Theory(DFT) at ROB3LYP/6-311 ++ G(2d,2p)//B3LYP/6-31G(d) level.The single-point energy(SPE), zero-point vibrational energy(ZPVE) and bond dissociation energy(BDE) are calculated in order to deduce the detail fragmentation pathways.