Figure 2: Effect of concentration of MBTH in the presence of 1.0 mL of 1% Ce(SO4)2 and concentration of Ce(SO4)2 and concentration of Ce(SO4)2 in the presence of 1.0 mL of 10-2 M MBTH on the formation of colored oxidative coupling product AVS (20 mg/mL−1) – MBTH – Ce(SO4)2.