Hyphenation of Trapped Ion Mobility to Two-Dimensional Mass Spectrometry for Protein Analysis in Complex Biomixtures

The analysis of complex biological mixtures remains a significant challenge in mass spectrometry (MS), particularly when using conventional direct infusion MS/MS approaches due to inherent limitations in resolving power and spectral complexity. Here, we demonstrate the integration of trapped ion mobility spectrometry (TIMS) with two-dimensional mass spectrometry (2DMS) to enable high-resolution TIMS-MS/2DMS experiments for detailed protein characterization within mixtures. TIMS provides separation based on the ion's size-to-charge ratio, effectively reducing the occurrence of chimeric tandem mass spectra containing fragments from more than one precursor ion. This coupling allows for an improved peak capacity and reduced ambiguity in tandem spectral interpretation. When applied to a model protein mixture, the TIMS-MS/2DMS method allows resolution of near m/z species, including isomeric and isonucleonic species, and it was possible to assign secondary fragmentation with greater confidence.