Development of a colorimetric paper sensor based on NH₂-MIL-125 MOF and bromocresol green for ammonia.

Authors

Azadeh Tavousi, Kiumars Bahrami, Masoud Shariati-Rad

Published in

Analytica chimica acta. Volume 1416. Pages 345733. Sep 22, 2026. Epub May 27, 2026.

Abstract

Ammonia is commonly known as a major air pollutant and serves as a vital ingredient in numerous industrial processes, such as the production of nitrogen-based fertilizers, textiles, and biofuels. This not only raises the costs of agricultural production but also impedes sustainable farming practices. As a result, monitoring ammonia emission has become a crucial task to improve nitrogen efficiency and reduce environmental impacts. Traditional detection methods, such as spectrometry, chromatography, and gas detection tubes, often involve high costs, complexity, and aren't user friendly.
In this study, a novel colorimetric paper sensor based on NH₂-MIL-125 MOF and bromocresol green (BCG) for measurement of ammonium as ammonia gas in agricultural fertilizer samples was developed. To optimize the sensor performance, a design of experiments (DOE) approach was used to investigate the effect of various factors, such as the concentrations of NH₂-MIL-125 MOF and bromocresol green (BCG) on the sensor response. The color change which is primarily observed in the B color value in the RGB (red, green, blue) color model, shows a strong correlation with ammonia concentration. The limits of detection (LOD) and limit of quantification (LOQ) for the B color value were determined to be 0.33 mg L^-1 and 1.1 mg L^-1, respectively. These values indicate high sensitivity of the sensor, with a coefficient of determination (R²) of 0.9220 for the B color value confirming its high accuracy. The sensor response reached its highest level after 60 min.
The sensor response is aligned with the RGB color model, providing a user-friendly and effective tool for assessing fertilizer quality in situ and monitoring ammonia release in real time. The comparative study indicated that the MOF combined with bromocresol green offers superior performance for ammonia detection compared to bromocresol green alone. The sensor takes advantage of the high surface area and ammonia adsorption capacity of NH₂-MIL-125 MOF, combined with the colorimetric response of BCG to ammonia.

PMID:
42401457
Bibliographic data and abstract were imported from PubMed on 05 Jul 2026.

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