Dual wavelength spectrophotometric determination of copper with chlorophosphonazo- III

Abstract

The dual wavelength spectrophotometric determination of copper has been developed with chlorophosphonazo-III (CPA-III) at <i>p</i>H 5. The Cu(ll)-CPA-lll reaction is sensitive and selective if DDTC is used for preconcentrating trace amounts of copper and separating other metal ions. The b-correction method can eliminate the effect of excess CPA-III from its Cu(ll) coloured solution to give out the real absorbance of the Cu-CPA-lll chelate. Beer's law is obeyed over the concentration range 0-1.20mg/l Cu and the molar absorptivity of Cu(CPA-III) at 610nm is 2.75 x 10⁴I.mol^-1 cm^-1. The detection limit of copper is 0.005mg/l The method has been applied for the determination of trace amounts of copper in waste water.