Figure 2.

The sensitivity of NH₄⁺ ion determinations via ¹H NMR analysis. ¹H NMR spectra of NH₄⁺ ions present at standard concentrations of 30, 60, and 125 µmol/L in aqueous solutions containing 20 mmol/L HCl (pH 2) and 10% (v/v) D₂O, with either 128 (left panel) or 1024 (right panel) scans conducted; these concentrations correspond to the final levels of all analyte solutions. The figure also shows the STN ratio of the central line of the NH₄⁺ ion signal for each spectrum acquired.