|Harnly, James - Jim|
Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2011
Publication Date: 1/19/2011
Citation: Lin, L., Harnly, J.M. 2011. Quantitation of flavanols, proanthocyanidins, isoflavones, flavanones, dihydrochalcones, stilbenes, and benzoic Acid derivatives after identification by LC-MS. Journal of Agricultural and Food Chemistry. 60:5832-5840. Interpretive Summary: Both identification and quantification of dietary polyphenols is very important for the estimation of daily intake of food polyphenols and evaluation of their human benefits. Quantifying these compounds is difficult because there are thousands of them and very few authentic standards. This paper introduces a general approach for quantification using one common standard. The structure of each compound is identified using liquid chromatography and mass spectrometry and a correct response factor is selected. The response factor, combined with calibration with the common standard, potentially allows for quantification of thousands of compounds. The concept and data presented in this paper will offer accurate, convenient, and efficient quantification of the polyphenols at a low cost. Quantification of the polyphenols will allow assessment of their impact on human health through clinical and epidemiological studies.
Technical Abstract: A general method was developed for the systematic quantitation of catechins, proanthocyanidins, isoflavones, flavanones, dihydrochalcones, stilbenes, and hydroxybenzoic acid derivatives (mainly hydrolyzable tannins) using the UV relative mole response factors (MRRF) of the reference standard from each group. The standards of each group have one UV maximum absorption in a closed wavelength range, thus, the MRRFP were measured at 278 nm for flavanols and proanthocyanidins, 274 nm for hydrolyzable tannins, 288 nm for flavanones, and 260 nm for isoflavones, respectively. MRRFP were used to quantify the phenolics of each group using only one standard more economically and conveniently, and the quantitation of catechins, proanthocyanidins and gallic acid derivatives of white tea was used as the example.