Identification of Flavonoids Using UV-Vis and MS Spectra

Flavonoids are a group of specialized metabolites that are ubiquitously found within the plant kingdom. While they fulfill various important functions within the plant, they are also utilized by humans in a variety of different fields such as medicine, food science, and agriculture. Thus, to elucidate the chemical composition of any given plant extract, extraction and identification of flavonoids are of high interest. In this chapter, we outline a general approach for analyzing flavonoids in complex plant extracts. Using blueberry as an example, we start by describing the extraction of plant material, followed by simple spectrophotometric measurements and thin layer chromatography (TLC), to get first insights into flavonoid content and composition. Furthermore, we describe a standard protocol for liquid chromatography-mass spectrometry (LC-MS) for the identification of specific flavonoids. By utilizing and combining the described techniques, general analysis of flavonoid content, composition, as well as identification of specific compounds can be realized within a complex metabolic mixture.