Fig. 3. Quantitative analysis ofthe drug propanolol from a salt-rich solution (25 mM
TRIS). The propanalol concentration is varied from 1.5 to 500 nM. The analyte solvent
is water/methanol and the ESI solvent is acidified methanol. The analysis was
performed in the triple-quadrupole mode, directly from mass spectra, without utilizing
MS2 or Multiple Reaction Monitoring (MRM). Background levels were low;
the signal-to-noise ratio was greater than 100 at the lowest concentrations.