ELECTROCATALYTIC DETERMINATION OF DOPAMINE BY POLY-L-HISTIDINE AND FERRICYANIDE COMPOUND FILM MODIFIED ELECTRODE

Poly-L-histidine and ferricyanide compound film modified glassy carbon electrode was prepared by electropolymerization.The electrochemical behavior of dopamine (DA) at the aboved mentioned modified electrode was studied.As shown by the experimental results,remarkable catalytic action of the modified electrode on the oxidation of DA was observed.Phosphate buffer of pH 7.6 was chosen as the base solution for the electrode reaction.Under the condition specified,the interference of ascorbic acid was effectively eliminated,since the difference of peak potentials (ΔEp) between dopamine and ascorbic acid achieved to a value of 200 mV.Linear relationship was obtained between the oxidation peak current (Ip) of dopamine and its concentration in the range from 1.0×10-7mol·L-1 to 2.2×10-5mol·L-1.Detection limit (S/N=3) found was 2.0×10-8mol·L-1.In its application to the determination of DA in injections,RSD′s found were 3.2%.