Validation and comparison of ammonia measurement techniques used to determine ammonia absorbed by passive absorption samplers

Emission of ammonia from agriculture is a major concern. The analytical analysis of ammonia is known to have some challenges and might be causing systematic errors. The effect of absorbing acids on an ion selective electrode (ISE) and the Berthelot colouring reaction, in terms of precision, was quantified. We show that commonly used acid absorbents do not have a significant influence on the precision of the ISE, whereas the acids had significant influence on measurements using the Berthelot reaction. Using the ISE in low-volume eluates (3 mL) did not influence the precision compared with the recommended 100 mL.