CHARACTERIZATION OF FLAVONOID STRUCTURES AND REACTIVITIES USING ONLINE CONTINUOUS FLOW KINETIC MEASUREMENTS AND HIGHER ORDER MS~n

摘要

The antioxidant characteristic of flavonoids may be responsible for their link to some therapeutic phenomena. Growing interest by horticulturists and food marketers in these nutritional polyphenolic compounds has fueled further study into reactive flavonoid chemistry. Traditional methods characterize the bulk antioxidant character or the degradation rate, but do not offer insight into the degradative mechanism or reactionary products being generated. In this work, an online capillary mixing device with adjustable reactor volume that can be modified to fit an electrospray inlet of a mass spectrometer (inspired by Wilson and Konermann, Anal. Chem.2003, 75, 6408-6414) was developed. This device allows an in depth study of flavonoid degradation mechanisms by providing continuous flow kinetic measurements as well as mass spectral information. A mixing device with an adjustable volume reactor was constructed by connecting a micro-mixing tee to two concentric capillaries. Flavonoid standards (quercetin, flavone, and flavanone) were introduced using a syringe pump. Another syringe pump delivered various solutions to the tee, allowing degradation studies by heat and oxidation. An electrospray ionization-ion trap-time of flight mass spectrometer was used to perform higher order fragmentation of resultant product ions. Iterative fragmentation pathways and mass accuracy was used to assess the structural identity of observed signals.