High-performance liquid chromatography-tandem mass spectrometry with post-column pH modification: Independent pH optimization for chromatographic separation and electrospray ionization.

Acidic or alkaline post-column infusion allows pH optimization for ionization conditions, independent of the pH optimization for chromatographic separation. The introduction of an additional modifier might also allow the minimization of matrix effects or directed formation of sodium adducts, without affecting the chromatographic separation.