Formation of positive product ions from substances with low proton affinity in high kinetic energy ion mobility spectrometry

Rationale Ion mobility spectrometry (IMS) instruments are typically equipped with atmospheric pressure chemical ionization (APCI) sources operated at ambient pressure. However, classical APCI-IMS suffers from a limited yield for nonpolar substances low proton affinity (PA). This is mainly due to ion clustering processes, especially those that involve water molecules, inhibiting the of these substances. Methods High Kinetic Energy (HiKE)-IMS decreased pressures and high reduced electric field strengths. As most reactions inhibited under conditions, PA in HiKE-IMS should differ APCI-IMS. To gain first insights into capabilities limitations HiKE-IMS, we investigated four model using HiKE-IMS-MS as function strength. Results The all have affinities between H2O (H2O)2 but exhibit different energies, dipole moments, polarizabilities. expected, results show differs considerably strengths cluster formation. In contrast, strengths, can be ionized via charge and/or transfer HiKE-IMS. Conclusions Considering detection polar PAs, IMS reach better limits than considering not detected, or only difficult detect, pressure, would beneficial.