Study of ion suppression for phenolic compounds in medicinal plant extracts using liquid chromatography–electrospray tandem mass spectrometry

• A study of several sources of ion suppression in LC-ESI–MS/MS was done.
• Both mobile phase and matrix effects play a major role in ionic suppression.
• The analyte/IS ratio is liable to differential ion suppression in similar matrices.
• Very similar matrices can demonstrate quite different ion suppression effects.
• Ion suppression effects were studied in 6 different extracts of medicinal plants.

A systematic study on the various sources of ion suppression in UHPLC-MS–MS analysis was carried out for 24 phenolic antioxidants in 6 different extracts of medicinal plants from Amazonia. The contributions of matrix effects, mobile-phase additives, analyte co-elution and electric charge competition during ionization to the global ion suppression were evaluated. Herein, the influence of mobile-phase additives on the ionization efficiency was found to be very pronounced, where ion suppression of approximately 90% and ion enhancement effects greater than 400% could be observed. The negative effect caused by the wrong choice of internal standard (IS) on quantitative studies was also evaluated and discussed from the perspective of ion suppression. This work also shows the importance of performing studies with this approach even for very similar matrices, such as varieties of medicinal plants from the same species, because different effects were observed for the same analyte.