Simultaneous determination of folic acid and uric acid under coexistence of l-ascorbic acid using a modified electrode based on poly(3,4-ethylenedioxythiophene) and functionalized single-walled carbon nanotubes composite

In this study, a highly sensitive and selective sensor based on poly(3,4-ethylenedioxy- thiophene) (PEDOT) and β-cyclodextrin functionalized single-walled carbon nanotubes (β-CD-SWCNT) composite was fabricated for the simultaneous determination of folic acid (FA) and uric acid (UA) under coexistence of ascorbic acid (AA). The modified electrode combined the features of PEDOT and SWCNT, which hold excellent conductivity, low cost and high surface areas for working as an efficient electron-mediator for FA and UA in the presence of AA. Voltammetric techniques separated the anodic peaks of FA and UA with activation overpotential, and the interference from AA was effectively excluded from FA and UA determination. The differential pulse voltammetry (DPV) data showed that the obtained anodic peak currents were linearly proportional to concentration in the range of 1-1000 μM with a detection limit (S/N = 3) of 0.8 μM for FA and in the range of 0.1-500 μM and with a detection limit of 0.07 μM for UA. It also presented superior reproducibility and long-term stability, as well as high selectivity. Moreover, the proposed sensor was successfully employed for the determination of FA and UA in spiked human urine samples with satisfactory results.