以磷酸为掩蔽剂的铁（II）-邻二氮菲分光光度法间接测定雪莲果中维生素C含量

摘要

利用维生素C定量将铁（Ⅲ）还原为铁（Ⅱ），铁（Ⅱ）与邻二氮菲发生显色反应，多余的铁（III）用磷酸溶液掩蔽．结果表明，在pH=4．0的溶液中，维生素C的线性范围为0-12．8μg·mL^-1，表观摩尔吸收系数8=2．03×10^-1L·mol^-1·cm^-1，加标回收率为97．30%-98．5％，变异系数为1．1％．该方法简便、准确、灵敏，是测量新鲜雪莲果中维生素C的一种有效方法．%This paper has investigated the chromogenic reaction between phenanthroline and Fe (II )by first reducing Fe (III)to Fe ( II )with vitamin C quantitatively, the surplus Fe( III )being occulted by phosphoric acid solution. The results indicate that the linear range of determination of vitamin C in solution at pH 4.0 is 0-12.8 μg.mL^-1. The apparent molar absorptivity is 2.03×10^4 L.mol^-1.cm^-1, the recovery is 97.3%- 98.5%, and the relative standard deviation is 1.1%. The method is simple, accurate and sensitive and is effective at the determination of vitamin C in Smallanthus sonchifolius.