Fabrication of an Electrochemical Sensor Based On Single-Walled Carbon Nanotubes Modified Gold Electrode for Determination of Ascorbic Acid

Since the discovery of carbon nanotubes (CNT) in 1991, research on CNT has progressedrapidly, and has became one of the most attractive part of nanotechnology [1].Carbon nanotubes are molecular-scale wires with high electrical conductivity, high chemical stability, and extremely high mechanical strength and modulus [2]. There have been many newapplications due to their unique chemical, electronic and mechanical properties. Recently,electrochemical studies suggested the ability of CNT to promote certain kindsofelectrontransferreactions[ 3]Nanotubes are categorized as single-walled carbon nanotubes (SWCNT) and multi-walled carbon nanotubes (MWCNT). Single-walled carbon nanotubes are constructed of asingle sheet of graphite of diameter 0.4-2.0 nm while multi-walled carbon nanotubes consist ofmultiple concentric graphite cylinders of increasing diameter of 2-100 nm [4],In thisexperimental research , the electrochemical manner of ascorbic acid was investigated based on modified gold electrod using single- wall carbon nanotube (SW CNT/AuE) as an electrochemical sensor. At first, ascorbic acid was measured at the level of non modified and modified goldelectrode with single- wall carbon nanotube; cyclic voltametric technique was used for determination of ascorbic acid. Ascorbic acid effectively accumulates on the (SW CNT/AuE)and causes redox peak (V.S Ag/AgCl) in a solution of ascorbic acid 300 μm with scan rate0.05 v/s .The height of redox peak become significantly higher than (AuE). And there was no peak on the AuE , before modification. the electrochemical parameters including : PH , kind of acid , concentration of acide , nanotube Scale. and scan rate have been optimized. Under the optimizedconditions, the peak current was linear with the concentration of ascorbic acid in the range of 10 to 650μm with a detection limit 2.951μm. The proposed method was successfully used for the determination of ascorbic acid in the samples of blood serum.

Keywords:

Ascorbic acid , Electrochemical Sensor , Single- wall carbon nanotube (SW CNT) and Cyclic voltammetry