Tris (2,2?-bipyridil) copper (II) chloride complex: a biomimetic tyrosinase catalyst in the amperometric sensor construction

The use of tris (2,2?-bipyridil) copper (II) chloride complex, [Cu(bipy)3]Cl2 /6H2O, as a biomimetic catalyst, is reported in the construction of an amperometric sensor for dopamine. The sensor was prepared modifying a glassy carbon electrode with a Nafion† membrane doped with the complex. The optimized conditions for the sensor response were obtained in 0.25 mol dm 3 Pipes buffer (pH 7.0) containing 150 mmol dm 3 H2O2, with an applied potential of /50 mV versus saturated calomel electrode (SCE). In these conditions, a linear response range between 9 and 230 mmol dm , with a sensitivity of 1.439/0.01 nA dm mmol 1 cm 2 and a detection limit of 4.8 mmol dm 3 were observed for dopamine. The response time for this sensor was about 1 s, presenting the same response for at least 150 successive measurements, with a good repeatability (4.8%) expressed as relative standard deviation for n /13. After its construction, this sensor can be used after 180 days without loss of sensitivity, kept at room temperature. The difference of the sensor response between four preparations was 4.2%. A detailed investigation about the sensor response for other eighteen phenolic compounds and five interfering species was performed. The sensor was applied for dopamine determination in pharmaceutical preparation with success. # 2002 Elsevier Science Ltd. All rights reserved.