The RF losses in NMR experiments on ionic solutions have been investig
ated by multi-NMR. The change of pi/2 pulse length (PW)90 for Na-23, C
l-35, 2D, O-17 and H-1 nuclei in NaCl/D2O solutions has been systemati
cally studied. Quantitative relation between (PW)90 values and the sam
ple specific conductivity sigma has been established. The increase in
(PW)90 values has been experimentally correlated to the reduction of t
he signal-to-noise ratio through O-17 measurements.