Refining Universal Procedures for Ammonium Quantification via Rapid 1H NMR Analysis for Dinitrogen Reduction Studies
Refining Universal Procedures for Ammonium Quantification via Rapid 1H NMR Analysis for Dinitrogen Reduction Studies
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DOI：
10.1021/acsenergylett.9b02812
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发表时间：
2020-03-13
影响因子：
22
通讯作者：
Simonov, Alexandr N.
中科院分区：
文献类型：
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作者：
Hodgetts, Rebecca Y.;Kiryutin, Alexey S.;Simonov, Alexandr N.
随着对通过电化学和光化学N-2还原的可持续氨合成的研究进展到包括更广泛的水性和非质子电解质，H-1 NMR光谱越来越多地被用作铵定量的手段。然而，该方法对实验参数高度敏感，如本文使用高度通用和稳健的NMR脉冲程序所证明的。我们证明了测量对分析溶液的最终pH值的灵敏度，并确定了[H+]浓度范围，从而实现了稳健的定量。我们比较直接定量与校准方法，前者是高度敏感的自旋弛豫效应，并确定后者作为最可靠的方法。这种方法，优化时，能够直接，快速定量（NH 4+）-N-14和（NH 4+）-N-15在12-22分钟内。检测限为5-10 μ M，这取决于溶剂，这符合目前的电化学和光化学N-2还原研究的需要。
As research on sustainable ammonia synthesis via electrochemical and photochemical N-2 reduction progresses to include a wider variety of aqueous and aprotic electrolytes, H-1 NMR spectroscopy is increasingly adopted as a means for ammonium quantification. However, this method is highly sensitive to experimental parameters, as demonstrated herein using a highly versatile and robust NMR pulse program. We demonstrate the sensitivity of the measurement to the final pH of the analyzed solution and identify a [H+] concentration range enabling robust quantification. We compare direct quantification versus calibration approaches to show that the former is highly sensitive to spin relaxation effects and identify the latter as the most reliable approach. This method, when optimized, enables direct, rapid quantification of both (NH4+)-N-14 and (NH4+)-N-15 within 12-22 min. The limit of detection of 5-10 mu M, depending on the solvent, which meets the needs of current electrochemical and photochemical N-2 reduction research.