期刊
CHEMSUSCHEM
卷 13, 期 1, 页码 88-96出版社
WILEY-V C H VERLAG GMBH
DOI: 10.1002/cssc.201901623
关键词
ammonia detection; electrocatalysis; ion chromatography; nitrogen fixation; photocatalysis
资金
- Beijing Natural Science Foundation [2182046]
- Beijing Key Laboratory of Environmentally Harmful Chemical Analysis
The reliable and accurate quantification of ammonia in electrochemical and photochemical experiments has been a technical challenge owing to the extremely low concentration of generated ammonia, interference from trace amounts of cations and organic compounds, and ammonia contamination from various sources. As a result, overestimation and significant errors may happen in many research works. Herein, accuracy and precision of ion chromatography (IC) are evaluated at different pH; excellent performance with a low detection limit (<2 mu g L-1) under acidic and neutral conditions is found, whereas the linearity is unsatisfactory in the low NH4+ concentration range (0-100 mu g L-1) under alkaline conditions. High concentrations of Li+ and Na+ are difficult to separate from NH4+ in conventional IC, but this can be solved by employing a high-exchange-capacity column or gradient elution. The interference effects of 14 common transition metal cations and 6 common organic compounds on the quantification of ammonium with low-level concentration (500 mu g L-1) using IC are systematically investigated, and the results demonstrate good robustness. The overestimation caused by ammonia contamination from reagent water, surroundings, and even the analytical grade of inorganic and organic reagents are confirmed and the results indicate the necessity to prepare and test fresh electrolyte solutions before each experiment, owing to the high sensitivity of acidic and neutral solutions to ammonia contamination from the surroundings. The ammonization of a Nafion membrane during experiments and the underestimation in quantification are also discussed. Finally, a reliable level of synthesized ammonia is identified and some recommendations are presented to improve the reliability and accuracy of ammonia quantification.
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