Mass spectrometric methods for the determination of flavonoids in biological samples

There is an ever-increasing interest in the biological effects of the bioflavonoids, members of the large group of plant polyphenols. Because of the aromatic character of these compounds, they have been analyzed by several chromatographic methods. In the case of high-performance liquid chromatography, they are readily detected by their ultraviolet absorbance or electrochemical properties. More evidence that the bioflavonoids undergo extensive metabolism during uptake from the gut and distribution around the body and in specific tissues is accumulating. In addition, free radical products at sites of inflammatory processes react with bioflavonoids and their metabolites, generating important new compounds of as yet unknown properties. For these reasons, careful examination of the chemical nature of bioflavonoids and their products in biological systems is absolutely required. Combination of mass spectrometry with the various chromatographic methods has proved to be highly successful in this regard. This review of the literature on the bioflavonoids is focused on the methods that are currently available for their qualitative and quantitative analysis by mass spectrometry and covers the period 2001-2003. Emphasis is placed on the description and value of existing methods, followed by an examination of emerging technologies.