Nitrogen Oxide Monitoring

Nitric oxide and nitrogen dioxide may be measured either separately or collectively as oxides of nitrogen (NOx) by either manual or automated techniques. The automated method is chemiluminescence atmospheric pressure and the manual method extensively used is the Saltzman method. Continuous colorimetric analyzers based on the Saltzman procedure have been used extensively. However, the use of analyzers based on this principle is not encouraged for several reasons. This chapter discusses the Modified Na-Arsenite Method that is based on a specific reaction of nitrite ion with diazotizing- coupling reagents to form a deeply colored azo dye, which is measured colorimetrically.

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