Electrochemical Determination of Ascorbic Acid Using Poly(Xanthurenic Acid) and Multi-Walled Carbon Nanotubes

Poly(xanthurenic acid) (polyXa) and multi-walled carbon nanotubes (MWCNT) hybrid composite have been successfully prepared to form polyXa-MWCNT for the determination of ascorbic acid (AA). One well defined redox couple has been recognized as the polyXa redox processes. This composite is stable in various scan rates and different pH conditions. It is surface-confined with the surface coverage of 2.3×10−9 mol cm−2 at polyXa-MWCNT/GCE. This electrode shows lower over-potential and higher current response to AA when compared to the bare electrode. Linearity is also found in other electrochemical techniques using linear sweep voltammetry (LSV) and amperometry. Applied potential at +0.3 V, it shows the sensitivity of 160.2 μA mM-1 cm-2 for the linear concentration range of 1×10−6–1.52×10−3 M, and detection limit of 0.1 μM (S/N = 3).