新催化动力学光度法‘花青-H_2O_2体系测定痕量铬(Ⅵ)

A Novel Catalytic Procedure for Ultratrace Chromium(Ⅵ) Gallocyanine H_2O_2 Indicator Reaction

在六次甲基四铵－盐酸介质中， 痕量铬（Ⅵ）显著催化Ｈ２Ｏ２氧化‘花青褪色的指示反应， 催化反应的表观活化能为６．８４ ｋＪ·ｍ ｏｌ－ １， 建立了测定痕量铬（Ⅵ）的动力学分析法， 线性测定范围为０～１５０ μｇ·Ｌ－ １，检出限为０．８μｇ·Ｌ－ １。常见离子中，除Ａｌ３＋ ，Ｃｕ２＋ ，Ｆｅ３＋ ，Ｆｅ２＋ 外，其余离子不影响测定。其中Ａｌ３＋ 的干扰可用Ｆ－ 掩蔽消除， Ｃｕ２＋ ，Ｆｅ３＋ ，Ｆｅ２＋ 的干扰可用ＥＤＴＡ 掩蔽消除。本法已用于测定湖水，矿井水和电镀废水中的铬（Ⅵ）。

A novel catalytic procedure for the determination of chromium(Ⅵ) was proposed based on the oxidation of gallocyanine with hydrogen peroxide catalyzed by chromium(Ⅵ). The apparent active energy of catalytic reaction is 6.84 kJ·mol -1 . The calibration graph is linear for 0~150 μg·L -1 Cr(Ⅵ), and the detection limit is 0.8 μg·L -1 . Most foreign ions have no interfering effect on the determination of Cr(Ⅵ), except for Al 3+ , Cu 2+ , Fe 3+ , Fe 2+ , the interference of Al 3+ can be eliminated by masking with F -, and that of Cu 2+ , Fe 3+ and Fe 2+ by adding appropriate amount of EDTA. The procedure has been applied to the determination of trace chromium(Ⅵ) in lake water, mine water and electroplating wastewater, the results were satisfactory.