The optimum conditions for spectrophotometric method for the determination of Ni2+ with chlorophosphonazo-III (CPA-III) were established and the nickel content in water samples has been successfully determined. In a pH 5.5 acetic acid-sodium acetate buffer medium, CPA-III and Ni2+2+ formed a 1:3 green blue complex and the maximum absorption wavelength of the complex is at 620 nm. Ni2+ content in a range of 0.1~3.5 μg/mL and absorbance shows a good linear relationship. The apparent molar absorption coefficient of method is e620nm = 1.40×104 L mol-1 cm-1and the detection limit is 0.075 μg/mL.
Nickel, Chlorophosphonazo-III, Spectrophotometry, Water sample