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研究了新显色剂5’-硝基水杨基荧光酮在溴化十六烷基三甲铵存在下与Cr(Ⅲ)的显色反应.在磷酸盐缓冲介质中(pH5.7～6.2),经沸水浴加热后.Cr(Ⅲ)与5’-硝基水杨基荧光酮形成组成比为1:2的紫色配合物.其吸收峰波长λ_(max)=590nm,对比度△λ=67nm,表观摩尔吸光系数为1.72×10~5,桑德尔灵敏度为3.0×10~(-4)μg·cm~(-2).Cr(Ⅲ)浓度为0～1.8μg/10ml时服从比耳定律.将Cr(Ⅲ)氧化为Cr(Ⅵ).采用阴离子交换树脂柱离干扰离子,方法用于水样中总铬和Cr(Ⅵ)的测定.Cr(Ⅲ)含量由差减求得.结果与二苯卡巴肼法一致.
The color reaction of 5 ’-nitrosalicylfluorone with Cr (Ⅲ) in the presence of cetyltrimethylammonium bromide was studied in a phosphate buffered medium (pH5.7 ~ 6.2) (Ⅲ) with 5’-nitrosalicylfluorone to form a purple complex with a compositional ratio of 1: 2. The absorption peak wavelength λ max (max) = 590 nm, the contrast △ λ = 67 nm , The apparent molar absorptivity was 1.72 × 10 ~ 5, and the sensitivity of Sander was 3.0 × 10 ~ (-4) μg · cm ~ (-2). When the Cr (Ⅲ) concentration was 0 ~ 1.8μg / The Cr (Ⅲ) is oxidized to Cr (Ⅵ), and the ion exchange resin is used to separate the interfering ions from the ions, and the method is applied to the determination of total chromium and Cr (Ⅵ) in water samples. The results are consistent with the diphenylcarbazide method.