I have a hard time seeing the blue color when adding KOH to my Total Kjeldahl Nitrogen (TKN) sample. Is there an easier way to do this?

Document ID

Document ID TE391

Published Date

Published Date 27/05/2017
Question
I have a hard time seeing the blue color when adding KOH to my Total Kjeldahl Nitrogen (TKN) sample. Is there an easier way to do this?
Summary
TKN indicator color change is difficult to see
Answer
The TKN indicator changes color at a certain pH. You can measure the pH of the sample, and then add the 8.0 N KOH until the sample reaches a pH of about 3 rather than looking for the blue color. Then add the 1.0 N KOH until the pH is between 4 and 6, and continue with the rest of the test.