Question

In water and wastewater analysis, Kjeldahl nitrogen (TKN) represents the sum of

• A. Organic nitrogen + nitrate nitrogen
• B. Organic nitrogen + nitrite nitrogen
• C. Organic nitrogen + ammonia nitrogen
• D. Ammonia nitrogen + nitrate nitrogen

Hint:

Remember: \[ \boxed{ \text{TKN} = \text{Organic N} + \text{NH}_3\text{-N} } \] Nitrate and nitrite are not included.

Answer 1

The Correct Option is C

Step 1: Recall the definition of Kjeldahl nitrogen.
The Kjeldahl digestion method measures nitrogen that is bound in organic compounds plus nitrogen present as ammonia.
Step 2: Note what it does not include.
The method does not convert nitrate or nitrite nitrogen into a measurable form, so those two are excluded from TKN.
Step 3: Match this to the options.
Only the option pairing organic nitrogen with ammonia nitrogen matches the actual scope of the Kjeldahl test.
\[ \boxed{\text{Organic nitrogen + ammonia nitrogen}} \]