PREPARATION OF GRAPHITE PASTE MODIFIED ELECTRODES SUPPORTED BY POLYANILINE AND CHROMIUM OXIDE NANOPARTICLES FOR ELECTROCHEMICAL DETECTION OF UREA

: A graphite paste modified electrodes with Cr2O3 2 O 3 nanoparticles and polyaniline nanocomposite were prepared to study the electrochemical behavior of urea in 1M KOH solution. A co-precipitation simple method was utilized to synthesis the Cr2O3 2 O 3 nanoparticles and chemical polymerization was used to prepare polyaniline (PANI). The modified electrodes under study were prepared by mixing of graphite powder with Cr2O3 2 O 3 nanoparticles and PANI in a ratio of (1/4 w/w). The electrodes were characterized by X-ray diffraction, field emission scanning electron microscopy, cyclic voltammetry and differential pulse voltammetry. The electrocatalytic activity of the electrodes toward urea was investigated. The results indicated that the Cr2O3/graphite 2 O 3 /graphite (Cr-G) electrode was more sensitive to urea than PANI /graphite (P-G) or PANI/Cr2O3/graphite 2 O 3 /graphite (P-Cr-G) electrodes. The cyclic voltammetry method was used to determine the linear range and limit detection. Accordingly, the modified electrode (Cr-G) showed a linear range of (0.001- 0.040) mM and a detection limit was 0.00637 mM. Moreover, the kinetic characteristics of urea, like transfer coefficient and the rate constant, were examined in an alkaline media.