Sensitive determination of herbicide trifluralin on the surface of copper nanowire electrochemical sensor

A novel voltammetric method for the determination of trifluralin is proposed based on a composit of carbon paste and copper nanowire as a sensitive sensor. The presence of copper nanowire in the composite film enhance the conductivity and as a result increased the electron transfer rate constant and so the current will increase. The composite exhibits a promising higher electrocatalytic activity towards the oxidation of trifluralin in pH 4.0 aqueous solution. The reduction peak currents of trifluralin increased remarkably and the reduction peak potential shifted positively at the nanostructuring electrode, compared with that at a bare CPE which show the enhanced effect of nanowire. The support electrolyte to provide a more defined and intense peak current for trifluraline determination was 0.05 mol L−1 phosphate buffer at pH 4.0. The fast Fourier transform square wave voltammetry was used as a new electrochemical technique in flow injection system to abtain more sensitivity by application of discrete fast Fourier transform method by background subtraction and two-dimensional integration of the electrode response over a selected potential range and time window, the signal-to-noise ratio has significantly increased and made the sensivity to be higher than other methods. The effective parameters such as frequency, amplitude, and pH were optimized to get the best sensitivity. As a result, the sensor showed a valuable response in linear concentration range of 100–0.02 nmol L−1 with a (limit of detection) LOD of 0.008 nmol L−1 and (limit of quantification) LOQ of 0.15 nmol L−1 for trifluralin. A good recovery was obtained for assay spiked urine samples and a good quantification of trifluralin was achieved in soil samples.