An Online post-column solvent-assisted ionization (OPSAI) method was developed for
enhancing the ionization of the beta-blocker propranolol utilizing normal phase LC-MS/MS.
Solvent-assisted electrospray ionization (SAESI) was studied by the introduction of the
assistant solvents A: 0.5% Formic acid in Isopropanolol, B: 0.5% Formic acid in
Isopropanolol− Water (1: 1), and C: 0.5% Formic acid in water into the electrospray
ionization chamber using a spray needle. Analyte molecules can be directly ionized by the …

The low or non-polar solvents of the mobile phase in normal phase chiral separations hinder
the ionization of the analyte molecules at the ESI-interface. Incorporation of assistant polar
solvents in the mobile phase would enhance the ionization of the analyte molecules at the
ESI-interface hence the signal intensity. The solvent assisted electrospray ionization (SAESI)
approach is based on the introduction of assistant polar solvent directly into the ESI-interface
under atmospheric pressure with the aid of the nebulizing gas. Online postcolumn solvent …