• Ensure that the test tube is clean before use.
• Clean the tube directly after use.
• Take the volume of the water sample as precisely as possible.
• Keep the dripping bottle perfectly vertical during dropping.
• Take care that no air bubbles are included in the drops.
1. Take a water sample of 20 ml.
2. Add 5 drops of NO3-1 test fluid and shake.
3. Add 5 drops of NO3-2 test fluid and shake again.
4. Add 1 spoon of nitrate powder (tube with green cap).
5. Shake for 20 seconds.
6. Wait 20 minutes and determine the NO3 -value using the included colour chart.