Selective Voltammetric Quantification of Nitrite on Lead Deposited In Situ

Nitrite detection is crucial in the medical, environmental, and energy fields. In nitrogen cycle electrochemistry, accurate nitrite quantification is particularly important for evaluating the selectivity and efficiency of fuel cells or hydrolyzers involving ammonia, hydrazine, or urea. We now present a voltammetric technique for detecting and quantifying nitrite (NO 2 – ) ions on lead‐modified glassy carbon electrodes, even in the presence of a tenfold excess of ubiquitous nitrate (NO 3 – ) ions. The glassy carbon surface is modified in situ by electrodeposition of an electrocatalytic Pb(s) layer from Pb 2+ ions. This layer is selective and quantitative toward nitrite reduction, with a limit of detection (LOD) of 6 μM, linearity up to 1000 μM, and relative standard deviation (RSD) of 1.6%, on par with or better than existing electroanalytical techniques toward nitrite quantification. The sensitivity of the method was assessed with important interfering electrolytes (nitrate, chloride, sulfate, and phosphate) and nitrogen cycle fuels and intermediates (ammonia, hydrazine, urea, and hydroxylamine). The method is tolerant to a tenfold excess of all interferents, except phosphate and hydroxylamine, which skew the measurement. The approach was further confirmed by a synthetic electrolyte mixture simulating a product stream from a urea‐oxidizing device, demonstrating reliable nitrite quantification under realistic conditions.