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Updated: May 16, 2026

Measurement of the Potential Rates of Dissimilatory Nitrate Reduction to Ammonium Based on 14NH4+/15NH4+ Analyses via Sequential Conversion to N2O
Published on: October 7, 2020
Precise determination of the ammonium ion in Mohr's salt: comparison between direct hydrodistillation and a sulfate
Omar Boualam1, Yassine Bouoidina2, Fatiha Mejbar1
1Laboratory of Materials, Processes, Catalysis, Agri-food, and Environment, Higher School of Technology, Sidi Mohammed Ben Abdellah University, Fez, Morocco.
Abstract:
The precise determination of the ammonium ion (NH4+) in Mohr's salt (Fe(NH4)2(SO4)2·6H2O) is crucial for industrial and analytical applications, but it can be compromised by the concomitant presence of sulfates (SO42-) and iron (Fe2+), which limit the complete release of ammonia and induce dosing errors. This study compares two approaches for the dosage of NH4+: direct hydrodistillation and an improved method based on the prior precipitation of sulfates with BaCl2, followed by the stoichiometric calculation of NH4+ from the precipitate of BaSO4. The hydrodistillation method leads to an underestimation of NH4+ (9.2-9.8 mg L-1, yield 95.7%, RSD 2.1%), due to an incomplete release of ammonia. On the other hand, the method based on the precipitation of sulfates provides more precise and reproducible results (9.9-10.3 mg L-1, yield 98.5%, RSD 1.5%). These results show a significant improvement in analytical performance. This approach constitutes a simple, robust, and reliable method for the determination of ammonium in sulfate-rich matrices.
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