Electrochemical sensor for detecting both oxidizing and reducing compounds based on poly(ethyleneimine)/phosphotungstic acid multilayer film modified electrode

A novel electrochemical sensor was prepared by alternatively deposition of anionic phosphotungstic acid (PTA) and polyelectrolyte poly(ethyleneimine) (PEI) on ITO glass through Layer-by-Layer assembly technique. Ascorbic acid and H2O2 were used as model drugs to investigate the electrocatalytic behavior of PEI/PTA multilayer film modified electrode in 0.1 M NaAc-HAc buffer (pH 5.0), respectively. The results showed that the corresponding current response of redox peak increased linearly with the increase of the concentration of them in certain ranges. The results of the standard addition method at three concentration levels testified that as-prepared electrode can be used to determine both of oxidizing and reducing compounds with low detection limits and high recoveries. And more, the response current of the electrode still can remain 96% of its initial activity after 100 cycles of CV scan. The PEI/PTA multilayer film modified electrode was further used to determine ascorbic acid in three commercially available fruit drinks, and the results were validated by high performance liquid chromatography, it was found that no statistically significant difference existed between the two methods. Compared with previous reports, the PEI/PTA multilayer film modified electrode can be used to determine both of oxidizing and reducing compounds with high sensitivity, good stability and reusability.