Electrocatalytic oxidation and voltammetric determination of nitrite on hydrophobic ionic liquid-carbon nanotube gel-chitosan composite modified electrodes

A novel room temperature ionic liquid (i.e., 1-octyl-3-methylimidazolium hexafluorophosphate, OMIMPF6)-multiwall carbon nanotube (MWNT) gel-chitosan (Chi) composite modified glassy carbon electrode (GCE) was fabricated and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), infrared spectroscopy (IR), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). The OMIMPF6-MWNT gel-Chi composite showed good conductivity stability, and extraction effect due to the synergic action of OMIMPF6, MWNT, and Chi. Furthermore, it was found that the OMIMPF6-MWNT gel-Chi composite had strong electrocatalytic effect on the oxidation of nitrite and at the OMIMPF6-MWNT gel-Chi/GCE nitrite could produce a very sensitive anodic peak. Under optimized conditions, the peak current was linear to nitrite concentration from 2.0 x.10(-8) to 6.0 x 10(-5) M. The detection limit was 1.0 x 10(-8) M. The electrode also exhibited acceptable stability, repeatability and selectivity. It was used successfully for the determination of nitrite in soil, sewage and sausage samples.