Electrochemical Behavior of Dopamine at Carbon Black Microelectrode Modified by the Coordination Complex of Nickel(Ⅱ) with N-Salicylidene Glutamic Acid

Carbon black microelectrode modified by the coordination complex of nickel(Ⅱ) with N-salicylidene glutamic acid was prepared. Electrochemical behavior of dopamine at this modified microelectrode was studied by using the JP-303 polarograph. It was found that in a phosphate buffer of pH 7.0,a sensitive oxidation peak was observed at 0.14 V with 3 times enhanced peak current. Linear relationship was obtained between the peak current and the concentration of dopamine in the range of 2.0×10-7-1.0×10-3mol·L-1,with a detection limit (3s) of 1.0×10-7mol·L-1. The proposed method was applied to the determination of dopamine in samples of dopamine hydrochloride injection,giving values of RSD′s (n=7) less than 3.5%,and recoveries in the range of 96%-103%.