双波长双指示剂催化光度法测定牛奶中的痕量铁

以酸性介质中痕量铁(III)催化的双氧水氧化中性红和亚甲基蓝褪色原理为基础,建立了双波长双指示剂催化动力学光度法测定痕量铁的新方法。确定的最佳试验条件为HCl用量为0.5 m L,亚甲基蓝用量为3 m L,中性红用量为0.4 m L,3%的双氧水用量为0.5 m L,反应时间为8 min,反应温度为100℃,线性范围为0.4~20.0μg/L,回收率在85%~89%之间,将该方法与经典原子吸收光度法相比,具有反应时间短、准确度高、精确度好的优点,适合牛奶中痕量铁的检测。

Determination for Trace Iron in Milk by Dual-indicator and Dual-wavelength Catalytic Kinetic Spectrophotometry

A new determination method for trace iron in milk by dual-wavelength and dual-indicator catalytic kinetic spec-trophotometry was established based on decoloration of hydrogen peroxide oxidation neutral red and methyl thionine chloride catalyzed by the trace iron (Ⅲ) in acid medium. The optimum conditions of demonstration experiments showed as follow: the dosage of HCl, methyl thionine chloride, neutral red, and hydrogen peroxide in 3% volume fraction were 0.5 mL, 3 mL, 0.4 mL, and 0.5 mL respectively, with reaction time of 8 mins and reaction temperature of 100℃. The linear range was from 0.4 to 20.0μg/L while the recovery rate was in 85%~89%. Compared with the classical method atomic absorption spectroscopy, the method have advantages of less reaction time, higher accuracy and better precision, which was suitable for determining trace iron in milk.