A modified sensitive carbon paste electrode for 5-fluorouracil based using a composite of praseodymium erbium tungstate

This paper describes the modification of a modified carbon paste electrode (CPE) using nanoparticles of praseodymium erbium tungstate (Pr:Er). The modified electrode was used for the sensitive voltammetric detection of an anticancer drug (5-fluorouracil (5-FU)) using. The modified-CPE was evaluated using cyclic voltammetry (CV), square wave voltammetry (SWV) and electrochemical impedance spectroscopy (EIS) and the resulting data showed the irreversible 5-fluorouracil oxidation peak around 1.0 V vs. Ag/AgCl. Some key parameters such as pH, the amount of the modifier, potential amplitude, step potential and frequency were studied and optimized. The square wave voltammetry (SWV) analytical calibration curve was linear in the range of 0.01-50 mu M, with a detection limit of 0.98 nM analyses. The electron transfer coefficient (a) was also determined to be 0.76. The analyte concentration was also determined in pharmaceutical formulations and recovery percentages were found to be in the range of 96-102%. The sensor had good reproducibility and repeatability with acceptable RSD values of 3.6%, and 1.02% and a rather long-term stability of around one month. The as-synthesized nanoparticles were also characterized using FESEM, TEM, FTIR and XRD techniques.