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. Iron (Ⅲ) was reduced to iron (Ⅱ) by vitamin C quantification, iron (Ⅱ) and phenanthroline color reaction, the excess iron (Ⅲ) was masked with phosphoric acid solution.The results showed that in the solution of pH = 4.0 , The linear range of vitamin C was 0 ~ 12.8μg.mL-1, the apparent molar absorptivity ε = 2.03 × 104L.mol-.1cm-1, the recoveries were 97.3% ~ 98.5% and the coefficients of variation were 1.1 The method is simple, accurate and sensitive and is an effective method to measure vitamin C in fresh yacon.