Voltammetric determination of trace amounts of fenitrothion on a novel nano-TiO2 polymer film electrode

A novel nano-TiO2 polymer modified glassy carbon (GC) electrode was developed for the determination of an organophosphorous pesticide, fenitrothion (phi-NO2), in citrate buffer solution. The electrochemical behavior of fenitrothion was characterized by using cyclic voltammetry. An irreversible form, phi-NO2, was transformed into a reversible redox couple (phi-NHOH/phi-NO), and it can be used to determine trace fenitrothion by square wave voltammetry. The experimental parameters, such as film thickness, pH value, accumulation potential and time were optimized. Interestingly, a cyclic voltammetric scan was observed to be more effective than a constant potential for the accumulation of fenitrothion. A linear response over a fenitrothion concentration of 2.5 x 10(-8) to 1.0 X 10(-5) M was exhibited, with a detection limit of 1.0 x 10-8 M (S/N = 3). The high sensitivity and selectivity of this film electrode was demonstrated by its practical application to the determination of trace amounts of fenitrothion in lake water and apple samples.