LUMINOL CHEMILUMINESCENCE-DELAY METHOD FOR DETERMINATION OF COPPER(II)

The copper(II)-catalyzed oxidation of cysteamine with oxygen was carried out in a basic medium involving luminol. After preferential oxidation of cysteamine to disulfide, a Cu(Il)-catalyzed luminol chemiluminescence (CL) reaction was subsequently commenced with hydrogen peroxide accumulated during the oxidation of cysteamine. Thus, a delay time from reaction initiation to a sharp flash of CL was observed. This delayed CL of luminol was applied to the determination of copper(II) by measuring the delay time or CL intensities. The delay time and the CL intensity at maximum light emission were linearly correlated with the Cu(II) concentration over the range from the detection limit of 3.0X10(-6) to 2.0X10(-5) M. The relative standard deviation of the CL intensity and the delay time in five successive experiments was 3.0% at 1.0X10(-5) M of Cu(II). The tolerance limits of Fe(III), Ni(II), and Zn(II) in the present method were 20- to 100-times higher than those in the conventional luminol CL method.