Determination of apremilast in rat plasma by UPLC-MS/MS in ESI-negative mode to avoid adduct ions formation.

Background: Quantification of target analyte by LC-MS/MS is sometimes hampering due to competitive adduct ions formation (sodium and/or ammonium) in positive ionization mode. A UPLC-MS/MS assay was developed for the determination of apremilast in rat plasma using ESI-negative mode to avoid adduct ions formation.

Method & Results: After extraction from plasma by ethyl acetate, analyte and IS were separated on Aquity BEH C column using acetonitrile-10 mM ammonium acetate (85:15) as mobile phase.