Electrochemical Determination of Catechol with Nano-gold Modified Glassy Carbon Electrode

A nanogold modified electrode behaving with electrocatalytic oxidation toward catechol was prepared by constant potential deposition of nanogold which was obtained by direct reduction of HAuCl4 onto the glassy carbon electrode.The electrochemical behavior of the modified electrode was studied by using a tri-electrode system with the modified electrode (or the bare glassy carbon electrode) as working electrode,SCE as reference electrode and Pt-wire as counter electrode.It was found that in a phosphate buffer solution of pH 7.5,a well-shaped redox peak of catechol (3.0×10-3mol·L-1 solution) was observed at the nanogold modified electrode,with Epa=140 mV,Epc=80 mV,Ipa/Ipc≈1.As compared with the bare glassy carbon electrode,a negative shift of Epa of 170 mV,a positive shift of Epc of 50 mV,a decrease of ΔE of 60 mV and a remarkable increase of peak current were obtained,denoting that the nano-gold modified electrode showed a distinct catalytic oxidation toward catechal,which was easier to be involved in the reversible redox reaction.Linear relationship was kept between Ipa and concentration of catechal in the range of 5.0×10-6-4.2×10-3mol·L-1,with a correlation coefficient of 0.997 6.Detection limit (3σ) of this method was found to be 5.0×10-7mol·L-1.RSD′s (n=10) tested at 5.0×10-4mol·L-1 was 2.9%.The recoveries tested gave values in the range of 98.0%-101.0%.