15 N NMR is very time consuming and was evaluated for a 15 N enriched sample, 15 NH4Cl (5.45 mg) using cryoprobe at 800 MHz using TLIS (C6H6/(H2O:D2O=75:25/CCl4). Spectra A & C in Figure show the 15 N spectra recorded with 2800 and 320 transients respectively from the standard-volume sample. Panels B & D show the corresponding 15 N spectra from the 1.8 cm SEN sample compared at the same signal height. S/N values of the 1.8 cm sample displayed ≈2.9 times higher S:N relative to the standard sample (Table ).