Electrochemical detection of the explosive taggant 2,3-dimethyldinitrobutane using a single-walled carbon nanotube employed TiO₂ composite film

A highly sensitive and fast method for electrochemical detection of 2,3-dimethyldinitrobutane (DMNB) on a graphite working electrode modified with a TiO₂ thin film including single-walled carbon nanotubes (SWCNTs) is proposed. Incorporation of the SWCNTs into the inorganic matrix allowed the preparation of a highly stable film with an integrated electrochemical chip. The sensing mechanism is based on the current change generated at the specific voltage due to the redox reaction of the DMNB NO₂ functional group. The detection limit and sensitivity were significantly improved due to the interaction between the SWCNTs and the analyte, which considerably enhanced the electron transferability. Under the optimized conditions, the linear range of the DMNB detection was 10 ppb to 10 ppm with a detection limit of 12 ppb, showing a sensitivity of 61 nA ppb^-1.