PEROXIDASE-CATALYZED CHEMILUMINESCENCE-DELAY OF LUMINOL FOR DETERMINATION OF TRACES OF COPPER(II)

Delayed chemiluminescence (CL) was observed in the copper(II)-catalyzed oxidation of cysteamine with oxygen in the presence of horseradish peroxidase (H RP) and luminol. After preferential catalytic oxidation of cysteamine by both Cu(II) and HRP, a HRP-catalyzed luminol CL reaction was subsequently commenced with hydrogen peroxide accumulated from the catalytic oxidation. Thus, a delay time from the reaction initiation to a sharp flash of CL was observed. The HRP-catalyzed CL-delay of luminol was applied to the determination of Cu(II). The delay time was linearly correlated with the Cu(II) concentration over the range from the detection limit of 5.0X 10(-9) to 1.5X10(-5) M. The detection limit of the present method is a factor of 30 times better than that of the conventional luminol CL method. The relative standard deviation of the delay time in five successive experiments was 3.2% at 1.0X10(-7) M of Cu(II). The present method was highly sensitive compared to the conventional luminol CL method.