Spectrophotometric determination of trace cadmium in galvanized waste water with 5-Br-PADAP-TritonX-100-β-cyclodextrin system

Based on the colour reaction of Cd(Ⅱ) and 2-[(bromo-2-pyridyl)-azo]-5-diethyl-aminophenol(5-Br-PADAP) in the presence of β-cyclodextrin(β-CD) and TritonX-100,a new method was found for the determination of cadmium in galvanized waste water by spectrophotometry.The absorption maxima of the complex is at 570 nm with apparent molar absorptivity of 2.40×105 L·mol-1·cm-1.Beer's law is obeyed in the range of 10~800 μg/L for Cd(Ⅱ).The regression equation of calibration curve is as follows: A=0.085 6 ρ+ 0.001 2.The correlation coefficient is 0.999 1.The method has been applied to the determination of trace cadmium in galvanization waste water with the relative standard deviation of 2.5%-3.2% and the recovery of 98.0%-102.0%.The results of this method are in good agreement with those of AAS.