Determination of Proanthocyanidins Content in the Skin of Lotus

Vanillin assay was carried out in HCl medium to determine the content of proanthocyanidins in the skin of lotus extract.Several parameters affecting the precision and accuracy of vanillin assay including HCl concentration,vanillin concentration,reaction time,reaction temperature,and sunlight were studied.The results showed that the proper reaction conditions were as the following: the medium comprised of 0.5 mL of sample,3 mL of 4%vanillin solution in methanol,and 1.5 mL of concentrated HCl in methanol,and the reaction was carried out at 30℃ for 20 min(measured at 500 nm).Assessment of the method by statistics showed that the method had high stability,reproduction,and recovery.