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

Abstract

The use of tris (2,2′-bipyridil) copper (II) chloride complex, [Cu(bipy) 3]Cl 2·6H 2O, 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 μmol dm −3 H 2O 2, with an applied potential of −50 mV versus saturated calomel electrode (SCE). In these conditions, a linear response range between 9 and 230 μmol dm −3, with a sensitivity of 1.43±0.01 nA dm 3 μmol −1 cm −2 and a detection limit of 4.8 μmol 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.