Ascorbate amperometric determination using conducting copolymers from aniline and N-(3-propane sulfonic acid)aniline.

The sequential electrochemical polymerization of aniline and N-(3-propane sulfonic acid)aniline (PSA) is proposed to construct a sensor able to detect ascorbate at physiological conditions. Compared to poly(aniline) modified electrode, a device with improved conducting and electrochemical properties at neutral pH is obtained. The electrochemical copolymerization of the same starting materials is also carried out. For a PSA:aniline ratio of 10:90, a polymer with a similar electrochemical behavior to the one grown in the sequential mode is observed. The detection of ascorbate was tested for both configurations at pH 7.2, the modified electrode is able to determine ascorbate at 0mV versus Ag/AgCl; an optimized sensor constructed by sequential polymerization can easily detect ascorbate concentrations with a detection limit of 2.2muM. Uric acid and dopamine does not interfere in the ascorbate determination.