Electrochemical sensing of nitrite in aqueous media with N, P-codoped biocarbon electrode

An electrochemical sensor was developed using N, P-codoped biocarbon modified glassy carbon electrode for ultrasensitive nitrite detection. The biocarbon was derived from sustainable chitosan biopolymer integrated with phosphorus functionality via triphenylphosphine. Controlled hydrothermal treatment and pyrolysis yielded a hierarchically porous structure with high surface area of 152 m²/g favorable for electrocatalysis. X-ray photoelectron spectroscopy confirmed uniform N, P-doping within the carbon lattice. Using ferro/ferricyanide redox probe, an excellent electron transfer rate constant of 18.7 s^− 1 was obtained. Amperometric method displayed two wide linear ranges of 0.1–500 µM and 500–2000 µM nitrite with a remarkably low limit of detection down to 90 nM. This sensor showed negligible interference from common metal ions and relative standard deviation below 5%. Over 95% initial current response was retained following continuous usage for 25 days, highlighting satisfactory stability. Successful practical analysis of various food products further proves the superiority over previous carbon nanomaterial based electrochemical nitrite sensors in terms of tunability, cost-effectiveness and scalability for real sample assays.