浊点萃取分光光度法测定水中Cr(Ⅵ)

Determination of Cr(Ⅵ) in water by spectrophotometry with cloud point extraction

利用二苯碳酰二肼显色,Triton X-100-正辛醇浊点萃取,建立了一种分光光度法测定水中Cr(Ⅵ)的新方法,并探讨了不同测定条件对测定效果的影响。优化后的测定条件为(总体积50 mL)1 mol/L稀硫酸加入量1.0mL、2 g/L二苯碳酰二肼溶液加入量1.5 mL、10 g/L Triton X-100溶液加入量1.5 mL、3 g/L苯甲酸溶液加入量4.0mL、正辛醇加入量5.0 mL。Cr(Ⅵ)质量浓度在0~20μg/L范围内符合朗伯-比尔定律,线性回归方程的相关系数为0.995 5。该方法应用于水样中痕量Cr(Ⅵ)的测定,相对标准偏差小于2.5%,加标回收率为95.7%。

A new method for determination Cr （Ⅵ）in water was established by spectrophotometry with diphenylcarbazide for color development reaction and Triton X-100-octanol for cloud point extraction. The effects of determination conditions were discussed. The optimum conditions were as follows： total volume 50 mL, volume of the 1.0 mol/L H2SO4 solution 1.0 mL, volume of the 2 g/L diphenylcarbazide solution 1.5 mL, volume of the 10 g/L Triton X-100 solution 1.5 mL, volume of the 3 g/L benzoic acid solution 4.0 mL, volume of octanol 5.0 mL. The Cr （Ⅵ） mass concentrations were fitted Beer-Lambert Law in the range of 0-20 μg/L with 0.995 5 of correlation coefficient of the linear regression equation. When the method was applied to determine trace Cr （Ⅵ）in water sample, the relative standard deviation was less than 2.5% and the recovery rate of standard addition was 95.7%.