Development and evaluation of field methods for ammonia in air

Area of Science:

• Environmental Chemistry
• Analytical Chemistry
• Occupational Health

Background:

• Accurate measurement of airborne ammonia is crucial for environmental monitoring and occupational safety.
• Existing methods require evaluation for reliability and practicality in diverse industrial settings.

Purpose of the Study:

• To evaluate and compare the accuracy and performance of three different methods for measuring airborne ammonia.
• To assess the influence of environmental factors like humidity and air velocity on measurement accuracy.

Main Methods:

• Two methods utilized filters impregnated with phosphoric acid, analyzed via ion chromatography or colorimetry (Nessler).
• Sampling was performed using active filter cassettes and passive monitors (Gasbadge).
• A third method, a colorimetric air-monitoring badge system (ProTek), was also evaluated.

Main Results:

• Filter-based methods demonstrated good accuracy and were not significantly affected by humidity.
• Ion chromatography analysis showed no interference from amines.
• Gasbadge passive monitors exhibited increased ammonia uptake at higher air velocities (0.2 to 1.0 m/s).
• The ProTek method showed poor accuracy, bias, and high blank values.

Conclusions:

• Impregnated filter methods, particularly when analyzed with ion chromatography, are reliable for airborne ammonia measurement.
• The ProTek colorimetric badge system is not recommended due to significant inaccuracies and bias.
• Field tests confirmed good agreement between filter methods, highlighting their suitability for industrial environments.