SYMPOSIA PAPER Published: 01 January 1976
STP32361S

Evaluation and Collaborative Testing of a Continuous Colorimetric Method for Measurement of Nitrogen Dioxide in Ambient Air

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A continuous colorimetric method for measurement of nitrogen dioxide (NO2) in ambient air, which uses Saltzman type absorbing solutions, was evaluated and then subjected to a collaborative test.

The evaluation shows that dynamic calibration is required to obtain reliable results. Static calibration is not reliable. The method write-up specifies dynamic calibration.

The collaborative test was carried out by having ten collaborators sample ambient air and the same ambient air spiked with a reliable source of NO2 for four days at a common site in Kansas City, Missouri; NO2 concentrations of 50 to 370 μg/m3 were sampled.

The results show that, based on 1-h avg concentrations, the within-laboratory standard deviation is 6 percent of the concentration over the range 90 to 370-μg NO2/m3, and the between-laboratory standard deviation is 14 percent of the concentration over the same range. The results also show that the method has a significant positive bias. This bias cannot be accurately quantitated because different collaborators give widely different biases, that is, the bias is collaborator dependent. The “average” bias ranges from +3 to +15 percent of the NO2 concentration over the just mentioned range.

The lower detectable limit of the method is 19 μg/m3.

Author Information

Margeson, JH
Environmental Monitoring and Support Laboratory, Environmental Protection Agency, Research Triangle Park, N. C.
Fuerst, RG
Environmental Monitoring and Support Laboratory, Environmental Protection Agency, Research Triangle Park, N. C.
Constant, PC
Midwest Research Institute, Kansas City, Mo.
Sharp, MC
Midwest Research Institute, Kansas City, Mo.
Scheil, GW
Midwest Research Institute, Kansas City, Mo.
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Details
Developed by Committee: D22
Pages: 144–155
DOI: 10.1520/STP32361S
ISBN-EB: 978-0-8031-4674-7
ISBN-13: 978-0-8031-0297-2