Abstract: The color reaction between Pb2+and CPA-Ⅲ was studied. In the medium of 0.2mol/L HCl, lead could form a violet-red complex with CPA-Ⅲ. The maximum absorption of the complex occurred at 650nm .The apparent molar absorptivity was 5.7×104L•mol-1•cm-1, and Beer’s law was obeyed in the range of 0～15μg(Pb)/25ml. This method has been applied to determinate trace lead in cosmetics and water successfully.

Key words: Spectrophotometry , CPA-Ⅲ , Lead