Ammonia

Description

This probe is used to measure ammonia (NH3) in aqueous solutions. In an aqueous solution, ammonia is in a pH dependent balance with ammonia ions (NH4+-Ionen). If the NH4+ ions are transformed into ammonia by the addition of a caustic solution, the probe will record the resulting ammonia. NH4+ ions as such will not be recorded.

The ammonia sensor comprises a pH glass electrode and a reference electrode. Both electrodes are immersed in an electrolyte. The electrolyte is separated from the medium to be measured by a hydrophobic gas permeable membrane. The pH value of the electrolyte changes by NH3 gas permeating the hydrophobic membrane. This local change of the pH value is measured by the integrated pH electronic at a resistance.