If samples are not acid preserved as specified in the TNT880 method for s-TKN, what should be done?
Samples results intended for s-TKN analysis that are not acid-preserved
Perform a separate Nitrite test with TNT839/TNT840 or similar method. Compare the value from the Nitrite test to the NO3+NO2 value obtained from the TNT880 s-TKN method. If the results are significant, then add the Nitrite result to both the Total Nitrogen and the NO3+NO2 results.