A Metal–Organic Gel-Carbon Nanotube Nanocomposite for Electrochemical Detection of Nitrite

A nanocomposite material consisting of a copper ion-based metal–organic gel (MOG-Cu) and multiwalled carbon nanotubes (MWCNTs) was prepared and served to construct a sensor for electrochemical detection of nitrite. The micromorphology of the MOG-Cu-MWCNT nanocomposite was characterized. The effects of MWCNT doping on the formation of a Cu-based MOG and its electrochemical property for nitrite electro-oxidation were evaluated. It shows that the optimal amount of MWCNTs does not influence the formation and nanofiber structure of the Cu-based MOG but can increase the electrochemical surface area and facilitate the interfacial charge transport. Hence, the oxidation current of nitrite at the MOG-Cu-MWCNT-coated glass carbon electrode (GCE) is considerably enhanced in contrast to the MOG-Cu/GCE. The analytical performances of the MOG-Cu-MWCNTs/GCE for electrochemical detection of nitrite were investigated. Operated in optimum conditions, the oxidation peak current at a potential of about 0.77 V versus a saturated calomel electrode shows direct proportion correlation with concentration of nitrite. The linear range is 0.3–100 μM. The sensor demonstrates fair anti-interference capacity, high sensitivity, a low detection limit (0.086 μM), satisfactory reproducibility, and storage stability, being a valuable tool for the electrochemical monitoring of nitrite in food samples.