二苯碳酰二肼分光光度法测定磁性材料中的铬(Ⅵ)

在硫酸介质中,二苯碳酰二肼可与铬(VI)发生显色反应生成紫红色的络合物,该络合物在540 nm波长处有最大吸收峰,由此建立测定磁性材料中铬(VI)含量的分光光度分析方法。本文对测定波长、显色pH值、显色剂用量以及显色时间等实验条件进行优化,在最佳实验条件下,络合物在540nm处的吸光度值与铬(VI)的浓度在0～0.3mg/L范围内呈良好的线性关系,其线性方程为A=0.839C-0.0048(c∶mg/L),相关系数r=0.9999;检出限为3.85×10~(-4)mg/L,回收率为94%～105%。采用碱浸煮方法提取磁性材料中的铬(VI),并用该方法对样品中铬(VI)的含量进行测定,并与SGS测得的结果进行对比。结果表明,该法的测定结果与SGS测得的结果相一致。该方法具有操作简便、快捷的优点,用于磁性材料中铬(VI)的测定,所得结果令人满意。

Determination of chromium in magnetic materials by diphenylcarbazide spectrophotometry

In the sulfuric acid medium at pH 2.0,chromium(Ⅵ) which is extracted by alkali in magnetic materials reacts with diphenylcarbazide to form a complex,whose maximal absorption wavelength is 540 nm.Beer's law is obeyed over the range of 0～0.3 mg/L for chromium(Ⅵ),the detection limit is 3.85×10~(-4)mg/L,and the recovery is 94%～105%.It is shown that the method is quick,highly accurate,easy to handle.And the method has been applied to the determination of chromium(Ⅵ) in magnetic materials with satisfactory results.