Simultaneous Voltammetric Determination of Epinephrine and Dopamine with Gold Electrode Modified with 2,3-Dimercaptosuccinic Acid

It was found that significant enhancement of electrochemical responses of both epinephrine (EP) and dopamine (DA) was observed at the 2,3-dimercaptosuccinic acid (DMSA) modified Au electrode (DMSA/Au) due to the catalytic action of the modified electrode.In a PBS of pH 6.7,values of oxidation peak current (ipc) of EP and DA found were 0.793 μA and 1.059 μA respectively,and reduction peak current (ipa) of DA found was 1.249 μA,while no reduction peak was observed with EP.In the co-existence of EP and DA,values of ipa were related only with the existence of DA,and values of ipc were the sum of ipc,EP and ipc,DA.Linear relationship between values of ipa and concentration of DA was found in the range of 4.0×10-6-1.0×10-4mol·L-1,and that between values of ipc and concentration of EP was in the range of 1.0×10-5-1.0×10-4mol·L-1.Based on these facts,a voltammetric method for simultaneous determination of EP and DA was proposed,giving values of recovery in ranges of 0.98-1.03 g·L-1 and 0.97-1.02 g·L-1 respectively.