Electrocatalysis at a Thin Multi-Wall Carbon Nanotube Film Modified Glassy Carbon Electrode

A sensitive and selective amperometric procedure, based on a glassy carbon electrode (GCE) modified with a thin multi-wall carbon nanotube (MWNT) film, for the determination of ascorbic acid (AA) was developed. The modified electrode showed excellent electrocatalytic activity towards the oxidation of AA. The oxidation potential of AA shifted negatively by as much as 460 mV to –18 mV (vs. SCE) at the modified electrode. Experimental variables were investigated and optimized. Amperometric tests of AA were performed at -10 mV. A linear response was obtained in the range of 5.0 10 -6 to 4.0 10 -3 M with a detection limit of 2.0 10 M. Interference studies indicated that the modified electrode is highly selective to AA in a mixture of AA, uric acid and dopamine. The proposed procedure was applied to the determination of AA in pharmaceutical and food samples with little or no sample pretreatment.