In the production of ammonium sulfate, a common nitrogen fertilizer, there is a possibility of contamination by sulfamic acid and ammonium thiocyanate during the production process, and this has been known to cause germination failure in plants. In this application, a standard solution of sulfamic acid and ammonium thiocyanate, as well as a sample solution containing ammonium sulfate and the addition of the standards was prepared. The analysis was performed with a IC NI-424 column, an anion analysis column described in the Japanese regulation for "Testing Methods for Fertilizers (2016*)". It was confirmed that sulfamic acid and ammonium thiocyanate were measured without any influence of impurities in the sample solution including standards.

*The version at the time of the application acquisition.

Sample Solution preparation:
1. Add 1500-µg each of sulfamic acid and ammonium thiocyanate to 1-g of ammonium sulfate.
2. Dissolve the mixture in water and make up to 100 mL.
3. With the aqueous solution, perform a 12.5-fold dilution with water, then filter it with a 0.45-µm filter to obtain the sample solution.


Sample : 20 μL
Standard solution (Sulfamic acid and Ammonium thiocyanate 3 mg/L each in H₂O)
Sample solution including standards (Sulfamic acid and Ammonium thiocyanate 1.2 mg/L each in 800 mg/L Ammonium Sulfate solution)
1. Sulfamate
2. Thiocyanate

Column       : Shodex IC NI-424 (4.6 mm I.D. x 100 mm)
Eluent       : 0.5 mM Phthalic acid + 4.0 mM p-Hydroxybenzoic acid 
               + 0.9 mM Sodium 1-Octanesulfonate + 2.0 mM Sodium 1-Hexanesulfonate 
               + 100 mM Boric acid aq.
Flow rate    : 1.0 mL/min
Detector     : Non-suppressed conductivity
Column temp. : 58 °C