Improved quantification of catechin and epicatechin in red rice (Oryza sativa L.) using stable isotope dilution liquid chromatography-mass spectrometry

Abstract Epimerization can change the catechin content and composition of samples during extraction analytical analyses. To control effect epimerization, we developed a novel stable isotope dilution liquid chromatography-mass spectrometry (LC–MS) method using catechin-2,3,4- 13 C 3 epicatechin-2,3,4- as stable-isotope-labeled internal standards (SIL-ISs). When SIL-ISs were used, epicatechin contents (104–109% 100–109% initial concentration, respectively) despite long storage times. In contrast, when L-2-chlorophenylalanine was used an standard, concentrations 88–97% 164–277% respectively, obtained after Furthermore, least significant epimerization highest extractability observed performed at 70 ℃ for 30 min. The recoveries red rice LC–MS two different between 100.72 118.67%, with relative standard deviations less than 3.67%.