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 (Nb 2 C@MWCNTs-STAB) for signal amplification was successfully constructed for sensitive detection of nitrite (NO 2 − ). Niobium carbide@multi-walled carbon nanotubes (Nb 2 C@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 Nb 2 C@MWCNTs. The electrostatic attraction between Nb 2 C@MWCNTs-STAB and NO 2 − was improved by the STAB , which enhanced the sensitivity of the constructed sensor for NO 2 − . Under optimized conditions, Nb 2 C@MWCNTs-STAB/GCE exhibited excellent analytical performance for detection NO 2 − with two wide liner ranges (0.1–100 μmol L −1 and 100–2000 μmol L −1 ) and a limit of detection of 0.022 μmol L −1 . Nitrite recovery tests in milk and spinach samples showed recoveries in the range of 89.82–104.52%. The NO 2 − 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.