What should my result be when using a Total Kjeldahl Nitrogen (TKN) primary standard such as Ammonia PTSA, Glycine PTSA, or Nicotinic acid PTSA (standard set Cat. No. 2277800)?

Document ID

Document ID TE393

Published Date

Published Date 27/05/2017
Question
What should my result be when using a Total Kjeldahl Nitrogen (TKN) primary standard such as Ammonia PTSA, Glycine PTSA, or Nicotinic acid PTSA (standard set Cat. No. 2277800)?
Summary
Expected Total Kjeldahl Nitrogen (TKN) primary standard results
Answer
The expected result using a TKN standard depends on whether you add the standard (solid) directly to the digestion flask or whether you prepare a solution from the standard and digest a portion of the solution. From a solid digestion (solid standard added directly to digestion flask), the result after the calculation in the last step of the procedure should be:
Ammonium PTSA 74,020 ppm
Glycine PTSA 56,640 ppm
Nicotinic Acid PTSA 47,430 ppm.

From a liquid digestion (solution prepared from 10 g standard diluted to 1 liter), the result after the calculation in the last step of the procedure should be:
Ammonium PTSA standard 740 ppm
Glycine PTSA standard 566 ppm
Nicotinic Acid PTSA standard: 474 ppm.
The results of the liquid digestion may differ if an amount other than 10 g were used to make the solution. If the actual result is significantly different (greater than 10 %) from the theoretical result, follow the standard solution method in the TKN test procedure using a 1 mg/L ammonia standard solution. If the results using an ammonia standard are correct, there may be a problem with the digestion procedure.