Howdle, Mark D. Eckers, Christine Laures, Alice M.-F. Creaser, Colin The use of shift reagents in ion mobility-mass spectrometry: studies on the complexation of an active pharmaceutical ingredient with polyethylene glycol excipients Gas-phase ion mobility studies of mixtures containing polyethylene glycols (PEG) and an active pharmaceutical ingredient (API), Lamivudine, have been carried out using electrospray ionization-ion mobility spectrometry-quadrupole-time-of-flight mass spectrometry (ESI-IMS-Q-TOF). In addition to protonated and cationised PEG oligomers, a series of high molecular weight ions were observed and identified as non-covalent complexes formed between Lamivudine and PEG oligomers. The non-covalent complex ions were dissociated using collision induced dissociation (CID) after separation in the ion mobility drift tube to recover the protonated Lamivudine free from interfering matrix ions and with a drift time associated with the precursor complex. The potential of PEG excipients to act as ‘shift reagents’, which enhance selectivity by moving the mass/mobility locus to an area of the spectrum away from interferences, is demonstrated for the analysis of Lamivudine in a Combivir formulation containing PEG and Lamivudine. Ion mobility spectrometry;Polyethylene glycol;Active pharmaceutical ingredient;Shift reagent;Quadrupole-time-of-flight mass spectrometry;Electrospray ionisation;Chemical Sciences not elsewhere classified 2009-03-25
    https://repository.lboro.ac.uk/articles/journal_contribution/The_use_of_shift_reagents_in_ion_mobility-mass_spectrometry_studies_on_the_complexation_of_an_active_pharmaceutical_ingredient_with_polyethylene_glycol_excipients/9392231