A Source for the Continuous Generation of Pure and Quantifiable HONO Mixtures

Abstract. A continuous source for the generation of pure HONO mixtures was developed and characterized, which is based on the Henry’s law solubility of HONO in acidic aqueous solutions. With the help of a peristaltic pump diluted nitrite and sulfuric acid solutions are mixed in a temperature-controlled stripping coil, which is operated with pure nitrogen or synthetic air at gas flow rates of 0.5–2 L min-1. Caused by the acidic conditions of the aqueous phase (pH ≈ 2.5), nitrite is almost completely converted into HONO, which partitions to the gas phase limited by its known solubility in water. The source shows a fast time response of ~2 min (0–90 %) at higher concentrations and an excellent long-time stability (2s noise