Reza Hajian - Department of Chemistry, College of Science, Gachsaran Branch, Islamic Azad University, 75818-63876,Gachsaran, Iran
Elaheh Gorjian - Department of Chemistry, College of Science, Gachsaran Branch, Islamic Azad University, 75818-63876,Gachsaran, Iran
Zahra Tayebi - Department of Chemistry, College of Science, Gachsaran Branch, Islamic Azad University, 75818-63876,Gachsaran, Iran

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.

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