Accelerating H NMR Detection of Aqueous Ammonia.

Direct electrolytic N reduction to ammonia (NH) is a renewable alternative to the Haber-Bosch process. The activity and selectivity of electrocatalysts are evaluated by measuring the amount of NH in the electrolyte. Quantitative H nuclear magnetic resonance (qNMR) detection reduces the bench time to analyze samples of NH (present in the assay as NH ) compared to conventional spectrophotometric methods. However, many groups do not have access to an NMR spectrometer with sufficiently high sensitivity. We report that by adding 1 mM paramagnetic Gd ions to the NMR sample, the required analysis time can be reduced by an order of magnitude such that fast NH detection becomes accessible with a standard NMR spectrometer. Accurate, internally calibrated quantification is possible over a wide pH range.