二苯碳酰二肼分光光度法测定水中六价铬方法的改进

Improvement of Method for Determination of Chromium(Ⅵ) in Water by 1,5-diphenylcarbohydrazide Spectrophotometry

结合环境监测实际工作，对GB／T7467—1987二苯碳酰二肼分光光度法测定水中六价铬的方法进行了适当的改进，在配制二苯碳酰二肼显色剂时，以乙醇代替有毒的丙酮作为溶剂，同时加入适量硫酸和磷酸，配成含混合酸的显色剂，分析时一次加入，简化操作步骤，提高了工作效率；对含色度、浊度的水样前处理方法进行了优化。改进方法与国标法测定结果无显著性差异，实际样品加标回收率在91％-110％之间，能够确保水样六价铬测定的精密度和准确度。

Combined with the work practice of environmental monitoring, the method for determi- nation of chromium （ Ⅵ ） by 1, 5-diphenylcarbohydrazide spectrophotometry （ GB/T 7467 - 1987 ） in water and wastewater was improved. The diphenylcarbohydrazide chromogenic agent was prepared by u- sing ethanol instead of toxic acetone as the solvent, adding appropriate amount of sulfuric acid and phos- phoric acid at the same time. When analyzing, the chromogenic agent containing mixed acid was added once, simplifying procedures and improving work efficiency. The pre-treatment method of water samples containing color and turbidity was optimized. The improved method has no significant difference in the re- suits compared with the national method, and the recovery of the actual samples was 91% to 110%, which could ensure the precision and accuracy in determination of chromium （V[） in water samples.