Potentiometric determination of nitrite with an ammonia gas sensor

Nitrite is converted completely to nitrogen by sulfamic acid, the excess of which is determined after conversion to ammonia by acid hydrolysis. Equal aliquots of sample are treated with increasing amounts of sulfamic acid, and potentials are measured after the hydrolysis. Nitrite in the range 1.5 × 10^-5–2 × 10^-2 mol l^-1 can be determined with errors less than 2%.