Method SM 4500-N B&C

Total Kjeldahl Nitrogen

This method is for the determination of total Kjeldahl nitrogen in water and wastewater samples.

Amino nitrogen of most organic materials and free ammonia in the sample are converted to ammonium in the presence of sulfuric acid (H2SO4) and upon addition of potassium sulfate and cupric sulfate catalyst. After addition of the base, ammonia is distilled from the alkaline medium and absorbed in boric or sulfuric acid. Ammonia is then determined colorimetrically, by ammonia selective electrode or by titration.

This method can also be used for sludge and sediment matrices.

(Standard Methods)


No Obligation Quotation for Analytical Services

If you would like us to provide a quote for laboratory analysis, just provide us with as much information as you can about your project (the more, the better) and we'll provide you a quote via email. As you are searching or browsing our Analytical Guide, you'll see the Request-A-Quote icon... just click on it to start the request process.

Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   28 days from sample collection to analysis.
Preservatives:   Add H2SO4 to a pH < 2 and store sample at 4°C.
Required Preps:   500mL plastic or glass bottle with Teflon-lined lid.
Collection Method:   Grab sampling
Analytical Methodology:   Colorimetric, ISE, titration

Analyte List*

Analyte Formula CAS Number Detection Limit
Nitrogen, Total Kjeldahl

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.