采用以盐酸为香草醛法的介质测定莲子皮原花青素的含量，考察了盐酸浓度、香草醛浓度、反应时间、反应温度、光照等因素对原花青素与香草醛显色反应的影响。结果表明，香草醛-盐酸法测定莲子皮原花青素含量的适宜条件为：0.5 mL提取液，3 mL 4%香草醛的甲醇溶液以及1.5 mL 浓盐酸的甲醇溶液，混匀后于30 ℃水浴保温20 min后即可测定A500。采用此法测定莲子皮原花青素的含量稳定性和重现性好，方法回收率高。

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.