A novel modified electrode was fabricated with 9-aminoacridine by electropolymerization in the phosphate buffer solution (PBS) (pH 7.4) and was characterized by cyclic voltammetry (CV). The modified electrode showed excellent electrocatalytic effect and high stability toward the electrochemical oxidation of dopamine (DA) and ascorbic acid (AA). Also, it showed a high stability for the determination of DA and AA simultaneously. Well-separated voltammetric peaks were observed for DA and AA on the modified electrode. The separation of two anodic peaks was 170 mV, which was large enough to eliminate the interference of AA and determine DA. The differential pulse voltammograms (DPV) were used for the measurement of DA by means of the poly(9-aminoacridine)-modified electrode in PBS at pH 7.4. A linear response to DA was observed in the concentration range from 1.5 x 10(-6) to 3.5 X 10(-3) mol L-1 with a correlation coefficient of 0.9998 and a detection limit (S/N = 3) of 1.0 X 10(-7)mol L-1. The proposed method was used to determine DA in DA-hydrochloride injection and showed excellent sensitivity and recovery. The ease of fabrication, good reproducibility, high stability, and low cost of the modified electrode are the promising features of the proposed sensor. (c) 2007 Wiley Periodicals, Inc.