Environ. Sci. Technol. 2003, 37, 2975-2981
Calibration and Evaluation of Nitric Acid and Ammonia Permeation Tubes by UV Optical Absorption J . A N D R E W N E U M A N , * ,†,‡ THOMAS B. RYERSON,† L. GREGORY HUEY,§ ROGER JAKOUBEK,† J O H N B . N O W A K , † C R A I G S I M O N S , †,‡ A N D F R E D E R I C K C . F E H S E N F E L D †,‡ NOAA Aeronomy Laboratory, Boulder, Colorado 80305, CIRES, University of Colorado, Boulder, Colorado 80309, and School of Earth and Atmospheric Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332
An ultraviolet (UV) optical absorption system has been developed for absolute calibrations of nitric acid (HNO3) and ammonia (NH3) permeation tube emission rates. Using this technique, dilute mixtures containing NH3 or HNO3, both of which interact strongly with many surfaces, are accurately measured at levels below a part per million by volume. This compact and portable instrument operates continuously and autonomously to rapidly (50 ng/min at 40 °C), HNO3 permeates through 2-5 cm lengths of 0.47 cm o.d. FEP tube. In the tubes with lower emission rates (
