VSL develops a portable calibration system for ammonia

VSL develops a portable calibration system for ammonia

There is a growing need for reliable calibration of ammonia analyzers and sensors used for monitoring of agricultural emissions. In and around open livestock housings, ammonia levels are typically low, placing stringent requirements on both analytical and calibration equipment.

To support such measurements, VSL developed a portable calibration system, known as TRACTOR (TRaceable Ammonia CalibraTOR). This system can dynamically generate ammonia in air at trace levels, under both dry and humid conditions. Humidity control is essential, as moisture can significantly affect measurement results through interference effects, chemical reactions, or changes in ammonia sorption on surfaces.

The TRACTOR participated in a comparison of dynamic ammonia reference gas standards from other national metrology institutes as part of the quantiAGREMI project. The comparison covered ammonia amount fractions of 50–400 nmol/mol in air, under both dry and wet conditions. The TRACTOR performed very well. A full paper on the comparison results is currently in preparation, but some results are available in this open‑access publication.

TNO has also used the TRACTOR to test and calibrate two of their mobile ammonia measurement systems both in the laboratory and in the field. These systems are mounted on a truck that is driven past farms to quantify ammonia emissions. A publicly available TNO report describing the testing and calibration is available online.