SYMPOSIA PAPER Published: 01 January 1976
STP32365S

Application of Gas Phase Titration in the Calibration of Nitric Oxide, Nitrogen Dioxide, and Ozone Analyzers

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A detailed procedural description of a technique developed and applied within the U. S. Environmental Protection Agency for the dynamic calibration of ambient air monitors for nitric oxide, nitrogen dioxide, and ozone is presented. A gas phase titration technique, utilizing the rapid gas phase reaction between nitric oxide and ozone, is used in such a manner that, with the concentration of one of the three gases known, the concentrations of the other two can be determined. A working cylinder of nitric oxide in nitrogen is standardized using one of three possible primary standards. Cylinder nitric oxide is then used as a secondary standard for routine calibrations. Ozone is added to excess nitric oxide in a dynamic calibration system, and a calibrated chemiluminescence nitric oxide analyzer is used as an indicator of changes in concentration. The decrease observed on the calibrated nitric oxide analyzer upon addition of ozone is equivalent to the concentration of nitric oxide consumed, the concentration of ozone added, and the nitrogen dioxide concentration produced. Once the concentration of the three gases has been determined, rapid and routine calibrations of ozone, nitric oxide, and nitrogen dioxide monitors may be performed at a common manifold. Experimental results showing the interrelationships that exist among the three gases are also presented.

Author Information

Rehme, KA
Environmental Monitoring and Support Laboratory, Environmental Monitoring Center, U. S. Environmental Protection Agency, Research Triangle Park, N. C.
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Details
Developed by Committee: D22
Pages: 198–209
DOI: 10.1520/STP32365S
ISBN-EB: 978-0-8031-4674-7
ISBN-13: 978-0-8031-0297-2