Accelerating (1)H NMR Detection of Aqueous Ammonia

[Image: see text] Direct electrolytic N(2) reduction to ammonia (NH(3)) is a renewable alternative to the Haber–Bosch process. The activity and selectivity of electrocatalysts are evaluated by measuring the amount of NH(3) in the electrolyte. Quantitative (1)H nuclear magnetic resonance (qNMR) detection reduces the bench time to analyze samples of NH(3) (present in the assay as NH(4)(+)) 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(3+) ions to the NMR sample, the required analysis time can be reduced by an order of magnitude such that fast NH(4)(+) detection becomes accessible with a standard NMR spectrometer. Accurate, internally calibrated quantification is possible over a wide pH range.