Voltammetric determination of nitrite by using a multiwalled carbon nanotube paste electrode modified with chitosan-functionalized silver nanoparticles.

A cyclic voltammetric method is described for the determination of nitrite by using a multiwalled carbon nanotube paste electrode (MWCNT) that was modified with chitosan-functionalized silver nanoparticles (Chit-AgNPs). The AgNPs were prepared by one step procedure using chitosan as stabilizing agent. The resulting modified AgNPs were drop-coated onto the electrode. By combining the advantages of chitosan, AgNPs (in the form of Chit-AgNPs) and MWCNT, the assay exhibits a remarkable improvement in the cyclic voltammetric response towards the oxidation of nitrite at a typical peak potential of 0.81 V (vs. SCE) in buffer of pH 4.0. The accumulation of nitrite on the electrode also was achieved, and this further enhances the analytical sensitivity. Under optimized conditions, the oxidation peak current increases linearly in the 100 nM to 50 μM nitrite concentration range, and the detection limit is 30 nM. The method has high selectivity for nitrite even in the presence of other potentially interfering ions. Graphical abstract Schematic illustration of the prepared chitosan functionalized silver nanoparticles (transmission electron microscope image) and modification of multi-walled carbon nanotube paste electrode with chitosan functionalized silver nanoparticles for the electrochemical oxidation of nitrite to nitrate.