Sensitive analytical detection of nitrite using an electrochemical sensor with STAB-functionalized Nb2C@MWCNTs for signal amplification

An electrochemical sensor based on stearyl trimethyl ammonium bromide -functionalized niobium carbide@multi-walled carbon nanotubes (Nb2C@MWCNTs-STAB) for signal amplification was successfully constructed for sensitive detection of nitrite (NO2-). Niobium carbide@multi-walled carbon nanotubes (Nb2C@MWCNTs) with high electrical conductivity and water dispersibility were first prepared in a one-pot hydrothermal synthesis, after which cationic STAB was added to overcome the negative surface charge on the Nb2C@MWCNTs. The electrostatic attraction between Nb2C@MWCNTs-STAB and NO2- was improved by the STAB, which enhanced the sensitivity of the constructed sensor for NO2-. Under optimized conditions, Nb2C@MWCNTs-STAB/GCE exhibited excellent analytical performance for detection NO2- with two wide liner ranges (0.1-100 mu mol L-1 and 100-2000 mu mol L-1) and a limit of detection of 0.022 mu mol L-1. Nitrite recovery tests in milk and spinach samples showed recoveries in the range of 89.82-104.52%. The NO2- residues in ham and pickled vegetable (cedrela sinensis) samples were analysed using the presented sensor and a spectrophotometric method, with no significant difference found between the results of the two methods.

Automated summary

An electrochemical sensor based on niobium carbide-functionalized multi-walled carbon nanotubes was successfully constructed for sensitive detection of nitrite. The sensor exhibited excellent analytical performance in various samples, with no significant difference found between the results of the sensor and a spectrophotometric method.