What do the units NH3-N mean?

Document ID

Document ID TE149

Version

Version 2.0

Status

Status Published

Published Date

Published Date 27/05/2017
Question
What do the units NH3-N mean?
Summary
Explanation of the nitrogen-ammonia units NH3-N chemical form
Answer
Most digital instruments can automatically convert the ammonia result between the chemical forms; ammonia NH3 and nitrogen-ammonia NH3-N.  The NH3-N iform uses the molecular weight of only the nitrogen atoms. The NH3 form uses the molecular weight of the entire ammonia molecule, 1 Nitrogen + 3 Hydrogen.

The nitrogen-ammonia NH3-N form is common because it relates to other nitrogen compounds such as nitrogen-nitrite NO2-N or nitrogen-nitrate NO3-N.

Provided below is the conversion chart to convert NH3 to NH3-N:

NH3 = NH3-N * 1.21589

Assumed atomic weights:
H: 1.008, N: 14.007