基于铬(Ⅵ)对过氧化氢与靛蓝胭脂红之间的氧化还原反应的催化作用,对应用此催化反应作为测定痕量铬的催化动力学荧光光度法的基础进行了研究。优化的反应条件如下:在10 mL总体积中依次加入1.0×10-3mol·L-1靛蓝胭脂红溶液1.5 mL,30%(w)过氧化氢溶液0.1 mL及pH 4.0乙酸-乙酸钠缓冲溶液3 mL。在65 ℃条件下反应11 min,迅速冷却至室温。在波长λex 330 nm和λem 415 nm处测其荧光强度,并计算ΔF(F-F0)值。所测得的ΔF值与铬(Ⅵ)的质量浓度在0.001~0.06 mg·L-1范围内呈线性关系。检出限(3s/k)为0.004 4 mg·L-1。应用此法分析了明胶胶囊,并进行了回收试验,测得平均回收率为98.0%。

Based on the catalytic action of Cr(Ⅵ) on the redox reaction between H2O2 and indigo carmine, the feasibility to develop a method for fluorophotometric determination of Cr(Ⅵ) on the basis of this catalytic reaction was studied. It was found that when in a solution of total volume of 10 mL, 1.5 mL of 1.0×10-3mol·L-1 indigo carmine solution, 0.1 mL of 30% (w) H2O2 solution and 3 mL of HOAc-NaOAc buffer solution of pH 4.0 were added in succession, and the mixture was heated at 65 ℃ for 11 min, and cooled rapidly to room temperature. When in the presence of Cr(Ⅵ), significant enhancement of fluorescence was observed as measured at λem of 415 nm with λex at 330 nm, and linear relationship between values of ΔF(F-F0) and mass concentration of Cr(Ⅵ) was found in the range of 0.001-0.06 mg·L-1, with detection limit (3s/k) of 0.004 4 mg·L-1. Test for recovery was made with capsule sample as matrixes by standard addition method, value of average recovery found was 98.0%.