What can cause a sample to form white-yellow particles during a Nessler ammonia test?

Document ID

Document ID TE133

Published Date

Published Date 25/01/2018
Question
What can cause a sample to form white-yellow particles during a Nessler ammonia test?
Summary
Interference to nitrogen-ammonia Nessler reagent causing white-yellow precipitant
Answer
The Nitrogen-Ammonia Nessler Method 8038 has several interferences. The normal color reaction using the Nessler reagent is a yellow color.  Samples with a high hardness concentration can form a white precipitate when the Nessler reagent is added.  This is due to the magnesium contributed by magneium carbonate.  The suggestions below can help to mitigate this interference.

- Dilute the sample to minimize hardness below 500 mg/L (CaCO3).
- Confirm the use of the Mineral Stabilizer Solution during the test method.
- If sample dilution is not possible, add 1-2 drops of Rochelle Salt Solution Catalog Number 172533 to the sample prior to testing. The Rochelle Salt will complex the magnesium in solution.

Reference the Water Analysis Handbook (WAH) Method 8038 for full list of interferences.