Multi-walled carbon nanotubes（ MWNTs） are noncovalently functionalized with azocarmine B（ ACB）

which make it has water dispersing ability. Dopamine electrochemical sensor is fabricated through dipping MWNTs-ACB water dispersion on gold electrode surface and dried under an infrared lamp. Voltammetric investigations indicate that the MWNTs-ACB film has good catalytic ability to the electrochemical oxidation of a small bio-molecule dopamine（ DA）. Under optimal detecting conditions

a wide linear response over the DA concentration of 1. 0 × 10-6

1. 0 × 10-3mol / L is obtained with a low detection limit of 5. 0 × 10- 7mol / L（ S / N =3）. Properties of sensor are checked and results show that the DA sensor has good stabilit

y and reproducibility

high sensitivity and selectivity. The sensor is applied to determination of DA in injection samples and results are satisfied.