The following introduces two national standard methods with simple operation and accurate data. No professional knowledge is required to detect the results.
1. Salicylic acid method (HJ 533-2009);
Detection principle: In the presence of alkaline medium (pH = 11.7) and sodium nitroferrocyanide, ammonia and ammonium ions in the water react with salicylate and hypochlorite ions to form blue compounds.
Operation process: Take a clean colorimetric tube, add the water sample to be measured to the 15mL scale of the tube, add a packet of ammonia nitrogen reagent (I), cover and shake to dissolve, add a packet of ammonia nitrogen reagent II after leaving for 2 minutes ), cover the lid and shake to dissolve. After 15 minutes, open the lid and place the colorimetric tube on the colorimetric card. The upper blank space is visually compared with the standard color scale from top to bottom, which is the same color as the solution in the tube. The color scale is the content of ammonia nitrogen (mg/L) in the water.
Application industry: The salicylic acid method can detect seawater because of its low detection limit. Widely used in aquaculture, aquarium, marine park, underwater world, household fish tank ornamental fish water detection.
2. Nano reagent method (HJ 533-2009);
The detection principle is that ammonia nitrogen in the form of free ammonia or ammonium ions reacts with Nessler's reagent to form a reddish-brown complex. The absorbance of the complex is proportional to the ammonia nitrogen content.
Operation process: 1. Add 1ml of water sample to be tested to the matching small test tube 2. Add 4 drops of matching reagent, cover and shake well 3. Take a test paper and immerse it in the small test tube for 10 seconds 4. Shake off the excess on the test paper The solution is immediately compared with the color chart
Industry application: The Nano method has a wide range and fast data output. Widely used in wastewater testing in printing and dyeing factories, textile mill wastewater, environmental protection projects, sewage treatment plants, etc.
3. High precision requirements, you can choose a tester, the operation and reading are more convenient. It can measure up to 50mg/L. Can meet most of the sewage detection requirements. The measurement range is relatively large and can be measured after dilution with pure water. Then multiply the dilution factor of the water sample.
(1) Estimate the ammonia nitrogen content of the water sample and select the appropriate range.
(2.) Add zero water samples according to the corresponding range:
When the water sample content is 0-5mg/L (ammonia nitrogen 0-5):
Aspirate 10mL (at the scale line) of the water sample to be tested into the colorimetric bottle, and adjust the instrument to zero.
When the water content is 0-50 mg/L (ammonia nitrogen 0-50):
Draw 1mL of water sample and 9mL of purified water into the colorimetric bottle, the instrument is zeroed.
(3) Take out the colorimetric bottle, add 6 drops of activator (A), shake well, then add 6 drops of activator (B), shake well. Countdown reaction for 3 minutes, reading.