Determination of nitrogen dioxide in red fuming nitric acid

Abstract

A simple method has been developed for directly determining the concentration of nitrogen dioxide (2NO₂⇌ N₂O₄) in red fuming nitric acid. The absorption due to nitrogen dioxide is measured in undiluted specimens at 500 nm, and the concentration taken directly from a calibration graph. The technique is accurate, precise and much more rapid than the standard titration procedure; it requires only small amounts and minimal handling of this dangerous material.