Continuous automatic determination of ammonia by using an integrated separation/detection unit.

Area of Science:

• Analytical Chemistry
• Environmental Chemistry

Background:

• Ammonia determination is crucial for agricultural soil and plant analysis.
• Existing methods for ammonia quantification can be time-consuming or require complex sample preparation.

Purpose of the Study:

• To develop and validate an automatic, continuous-flow photometric method for ammonia determination.
• To assess the method's applicability and accuracy in analyzing agricultural samples.

Main Methods:

• The proposed method utilizes the Berthelot reaction with temporary immobilization of the product on Sephadex QAE within a flow cell.
• Elution of the retained product is achieved using a cationic surfactant in the carrier solution.
• Measurements are performed photometrically in a continuous-flow system.

Main Results:

• The method accurately quantifies ammonia in the range of 0.4–20.0 mg/ml with a relative standard deviation (RSD) of 0.8%.
• A sampling frequency of 13 samples per hour was achieved.
• The determination limit can be improved tenfold by increasing the flow cell path length, albeit with a reduced sampling rate.

Conclusions:

• The developed continuous-flow photometric method provides a reliable and efficient approach for ammonia determination.
• The method is suitable for the analysis of ammonia in agricultural samples like plants and soils.
• It offers a viable alternative to standard methods, enhancing analytical throughput.