to 500 lmol L1 caused a remarkable increase in the DI of the CL
system. However, above the concentration of 500 lmol L1 the
DI is gradually decreased, possibly due to the self-absorption of
the emitted radiation by the luminol in its higher concentrations
[27]. This causes a decrease in the DI of the CL system. So,
500 lmol L1 luminol was selected as the optimal concentration
for further experiments.