Highly sensitive and selective determination of thiocyanate using gold nanoparticles surface decorated multi-walled carbon nanotubes modified carbon paste electrode

Gold nanoparticles and multi-walled carbon nanotubes were used to fabricate a modified electrode, as a highly sensitive and selective voltammetric sensor, for the determination of thiocyanate. A fast and easy method for the fabrication of gold nanoparticles/multi walled carbon nanotube/carbon paste electrode (GNPs/MWCPE) by cyclic voltammetry was used. Scanning electron microscopy (SEM) image demonstrated that the gold nanoparticles deposited on MWCNTs/CPE, with an average size of 30 nm. By combining the benefits of GNPs/MWCNTs and CPE, the resulted modified electrode exhibited outstanding electrocatalytic activity in terms of thiocyanate oxidation by giving much higher peak currents than those obtained for the unmodified CPE and also the MWCNTs-modified electrode. The effects of various experimental parameters on the voltammetric response of thiocyanate were investigated. At the optimum conditions the sensor has a linear response in the 0.01–200.0 μmol L−1 concentration range, a very good detection sensitivity (2.9046 μA L μmol−1), and a low detection limit of 5 × 10−3 μmol L−1 of thiocyanate. The proposed electrode was used to the determination of SCN– in saliva, urine and water samples and the results were found to be in good agreement with the values obtained by standard method.