Electrochemical Determination of Vitamin C on Glassy Carbon Electrode Modified by Carboxyl Multi-walled Carbon Nanotubes

A new sensor was constructed by using a glassy carbon electrode (GCE) modified with carboxyl multi-walled carbon nanotubes (MWCNTs) dispersed in N,N-dimethylfomamide (DMF) media. Compared with bare GCE, the resultant DMF/carboxyl/MWCNTs/GCE was used to detect vitamin C (VC) in samples with higher sensitivity, lower detection limit and better repetitiveness. Under the optimal conditions, the obtained sensor presented linear response to VC in the range of 1.0x10(-6) to 1.0x10(-3) mol/L, the linear regression equation was i(pa)(10(-5)A)= 0.226 c (10(-4) mol/L) + 1.351 with the linear correlation (r): 0.999, the limit of detection(LOD): 2.5x10(-7) mol/L. As tomato samples were detected by the DMF/carboxyl/MWCNTs/GCE, the recovery rate was in the range of 99%similar to 105%. Relative Standard Deviation (RSD) was in the range from 3.18 to 4.21. The proposed electrode was used to detect VC concentration in real samples successfully.