Development of standard reference materials for air quality measurement

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Accurate air pollution measurements rely on well-characterized gaseous Standard Reference Materials (SRMs).
• Ensuring the stability, homogeneity, and accuracy of SRMs is crucial for reliable environmental monitoring.
• The National Bureau of Standards (NBS) has a program focused on developing these critical materials.

Purpose of the Study:

• To report on the long-term studies of gaseous SRMs for air pollution measurements.
• To characterize the stability and homogeneity of specific gas mixtures.
• To describe methods for achieving accuracy in SRM preparation and analysis.

Main Methods:

• Long-term studies of gas systems and analysis of numerous prepared samples.
• Development and application of absolute analytical methods.
• Utilizing gravimetric standards and dynamic dilution systems for accuracy.
• Employing permeation tubes for reactive gases like sulfur dioxide and nitrogen dioxide.

Main Results:

• Characterization of stability over time and within-batch homogeneity for carbon monoxide in nitrogen and nitric oxide in nitrogen SRMs.
• Demonstrated accuracy achievable with gravimetric standards and dynamic dilution systems.
• Collected data on the stability and accuracy of permeation devices for reactive gases.

Conclusions:

• The NBS has successfully developed and characterized gaseous SRMs essential for accurate air pollution monitoring.
• Long-term studies validate the reliability and consistency of these critical reference materials.
• Established methods ensure the accuracy and usability of SRMs for diverse air quality applications.