二苯碳酰二肼分光光度法测定硝酸铁中微量铬(Ⅵ)

Determination of Trace Chromium(Ⅵ) in Ferric Nitrate by Diphenylcarbazide Spectrophotometry

在硫酸-磷酸介质中，未经分离除去高浓度的Fe（Ⅲ），以二苯碳酰二肼作显色剂，与Cr（Ⅵ）形成有色配合物，在波长540nm处有最大吸收峰，显色程度与Cr（Ⅵ）含量成正比，Cr（Ⅵ）含量在0—50μg·（50mE）。范围内呈良好的线性关系，摩尔吸光系数为4．0×10^5L·mol^-1·cm^-1。将方法应用于工业品硝酸铁中微量铬的测定，相对标准偏差为4．06％（n=6），加标回收率在91．5％～105．2％之间。

In sulfuric acid and phosphoric acid medium, after removal of high concentration of Fe （ Ⅲ ） without separation, diphenylcarbazide formed a colored complex with Cr（ Ⅵ ） and it had a maximum absorption peak at wavelength of 540nm. The color degree was directly proportional to content of Cr （ Ⅵ ） and the content of Cr （Ⅵ ） showed a good linear relationship between 0-50 μg/50mL. Molar absorption coefficient was 4.0 × 10^5L · mol^-1 × cm^-1. The method was applied to determine trace chromium in industrial ferric nitrate and the relative standard deviation was 4.06% （n=6）, the recovery rate was 91.5%-105.2%.