Calibration and Evaluation of Nitric Acid and Ammonia Permeation Tubes by UV Optical Absorption
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- 作者：J. Andrew Neuman ; Thomas B. Ryerson ; L. Gregory Huey ; Roger Jakoubek ; John B. Nowak ; Craig Simons ; and Frederick C. Fehsenfeld
- 刊名：Environmental Science & Technology
- 出版年：2003
- 出版时间：July 1, 2003
- 年：2003
- 卷：37
- 期：13
- 页码：2975 - 2981
- 全文大小：159K
- 年卷期：v.37,no.13(July 1, 2003)
- ISSN：1520-5851
文摘
An ultraviolet (UV) optical absorption system has beendeveloped for absolute calibrations of nitric acid (HNO3)and ammonia (NH3) permeation tube emission rates. Usingthis technique, dilute mixtures containing NH3 or HNO3,both of which interact strongly with many surfaces, areaccurately measured at levels below a part per million byvolume. This compact and portable instrument operatescontinuously and autonomously to rapidly (<1 h) quantifythe emission of trace gases from permeation devicesthat are commonly used to calibrate air-monitoringinstruments. The output from several HNO3 and NH3permeation tubes, with emission rates that ranged between13 and 150 ng/min, was examined as a function oftemperature, pressure, and carrier gas flow. Absorptionsof 0.015% can be detected which allows a precision (3
) of±1 ng/min for the HNO3 and NH3 permeation tubesstudied here. The accuracy of the measurements, whichrelies on published UV absorption cross sections, is estimatedto be ±10%. Measurements of permeation tube emissionrates using ion chromatography analysis are made to furtherassess measurement accuracy. The output from theHNO3 and NH3 permeation tubes examined here was stableover the study period, which ranged between 3 monthsand 1 year for each permeation tube.
) of±1 ng/min for the HNO3 and NH3 permeation tubesstudied here. The accuracy of the measurements, whichrelies on published UV absorption cross sections, is estimatedto be ±10%. Measurements of permeation tube emissionrates using ion chromatography analysis are made to furtherassess measurement accuracy. The output from theHNO3 and NH3 permeation tubes examined here was stableover the study period, which ranged between 3 monthsand 1 year for each permeation tube.