Ammonium Analysis
Reagents
Sodium Salicylate Solution
In a 100 ml volumetric flask of DI water mix
- 6.8 g sodium salicylate
- 5.0 g sodium citrate
- 5.0 g sodium tartrate
- 25 mg sodium nitroprusside
NaOH Solution
In a 100 ml volumetric flask
- 6 g sodium hydroxide
- Bring to volume.
Bleach Solution
Make fresh each day in 50 ml volumetric flask
- 1 ml bleach
- Bring to volume with NaOH Solution.
Matrix
- In a 1 liter volumetric flask
- 74.59 g KCl (1M KCl) & Bring to volume with DI water.
Standard Dilutions
Concentration (ppm ) | Standard (ml) | 1 M KCl
0 0 10
0.5 0.2 9.8
1 0.4 9.6
2.5 1 9
5 2 8
10 4 6
15 6 4
25 10 0
Standard (25 ppm NH4)
In 100 ml volumetric flask
- 10 ml NH4 standard (Certified 250 ppm NH4)
- Bring to volume with matrix
- Mix standards in 15 ml centrifuge tubes using dilutions from the adjacent table.
Procedure
In a clear 96-wellplate
- Assay the standards in duplicate (Col. 1 & 2) - 50 μl standard.
- Assay the samples in quadruple – add 50 μl of sample to each well. A 96-wellplate can hold 20 samples with standards.
- Add 150 μl salicylate solution to each well using the multi-channel pipette.
- Add 150 μl bleach solution to each well using the multi-channel pipette.
- Tap edge of plat to mix well and incubate 50 min. Read plate at 650 nm.
Method detection limit: 0.1 - 50 ppm
Created 7/20/07 Revised 10/10/11