Recent developments in proteomics increasingly point at the multiplicity of conformations (i.e. tertiary and quaternary structures) assumed in many cases by otherwise identical proteins in nature, and the critical biological effect of these differences on the protein function. Thus the capability to characterize all conformations encountered in the proteome becomes a necessary part of complete proteomic analyses. Standard protocols of mass-spectrometry-based proteomics (even in the top-down approach) are inherently unable to distinguish variant protein conformations. Ion Mobility Spectrometry (IMS) separates different conformations of gas-phase macromolecular ions and provides some data about their structures. However, the information is limited to the orientationally averaged cross-section, which nearly always lacks the specificity to fully characterize large ion geometrics. Also, because of the limited instrumental resolution, ion packets separated in IMS commonly contain multiple conformational isomers. Field-Asymmetric waveform Ion physical basis of FAIMS separations remains obscure with a number of properties likely combined in an uncertain and variable fashion, and no means to extract the ionic structure from FAIMS data currently exist. FAIMS also suffers from a very limited resolution and variable focusing effect that impedes analyte quantitation.