Expanding the analytical power of ion mobility spectrometry: An integrated SFC-IMS system with soft X-ray ionization and ultra-fast dual-polarity operation.

Building on recently developed ion mobility spectrometry (IMS) instrumentation, this work presents the first chiral and achiral analyses of multicomponent mixtures and real-world samples using supercritical fluid chromatography (SFC) coupled to soft X-ray IMS. The implementation of ultra-fast polarity switching IMS technology, previously developed for hyphenated gas chromatography (GC), enables a new application of dual-polarity detection and extends the range of detectable compounds. Additionally, the quasi-simultaneous detection of charged analyte species formed by soft x-ray ionization in both positive and negative ion modes within a single chromatographic measurement enables comprehensive analysis with improved confidence in compound identification based on polarity-dependent ionization efficiency. To evaluate the capabilities and limitations of SFC-X-ray-IMS, the influence of varying proportions of methanol as a modifier on the amount of the reactant ions and, subsequently, on the amount of analyte ions was investigated. Reliable detection of analyte ion species of opposite polarities was demonstrated in the simultaneous separation of the enantiomers of Tröger's Base and hydrobenzoin. Finally, the system was employed for the determination of spiked nitrosamines and the semi-quantitative assessment of nicotine in tobacco-free nicotine pouches.