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

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ε=2.03×104L.mol-.1cm-1,加标回收率为97.3%～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.

Indirect determination of the vitamin C content in Smallanthus sonchifolius by phenanthroline-Fe ( II ) with phosphoric acid as masking agent

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.