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K-State Today

February 10, 2020

High-resolution differential ion mobility spectrometry is topic of next Biochemistry and Molecular Biophysics Seminar

Submitted by Biochemistry and Molecular Biophysics

Alexandre Shvartsburg, professor of chemistry at Wichita State University, is the featured speaker for the Biochemistry and Molecular Biophysics Seminar at 4 p.m. Wednesday, Feb. 12, in 120 Ackert Hall. Shvartsburg will present "High-Resolution Differential Ion Mobility Spectrometry: Frontline Technology and Applications across Chemistry."

Shvartsburg was born in Russia where he was involved in space research. He changed his focus to chemistry in the the U.S., earning his master's degree from the University of Nevada and his doctorate from Northwestern in the then nascent field of ion mobility/mass spectrometry — Jarrold's group. He was a NSERC postdoc at York University, Toronto, and worked for the FDAl, National Center for Toxicological Research in  Jefferson, Arkansas, and Pacific Northwest National Laboratory in Richland, Washington, where he started developing FAIMS technology and applications. He has then moved to academia at Wichita State University and launched a start-up, Heartland MS, to share frontline IMS/MS systems with the broader analytical community. His work was recognized by several awards, most recently NSF CAREER and Presidential Early Career Award for Scientists and Engineers.

With all the power of modern MS, most biological and environmental samples require substantial prior separations. Chromatography and electrophoresis are now increasingly replaced or complemented by ion mobility spectrometry, or IMS, in gases. A nonlinear method of differential or field asymmetric waveform IMS, or FAIMS, based on the derivative of mobility as a function of electric field is much more orthogonal to MS than linear IMS based on the absolute mobility, enabling exceptional isomer separations.

We will review the fundamentals, instrumentation, and exemplary applications of high-definition FAIMS/MS developed in our lab. A major challenge in proteomics is characterizing the mixtures of isomeric proteoforms with variant positions of post-translational modifications, or PTMs, or isomerism within the PTM, where MS/MS is limited by lack of unique fragments. We can disentangle mixtures of peptides up to ~6 kDa with common PTMs by FAIMS and characterize them by ETD on various MS platforms including Orbitrap. The D-amino acid containing peptides, or DAACP, are also resolved from L-analogs. A similar problem in metabolomics is elucidating the isomeric diversity of lipids that comprises multiple isomer types including transacylation and the position and cis/trans geometry of double bonds. We could resolve over ~80% of lipid isomers across types, and more in conjunction with OzID for double bond localization. Finally, FAIMS can resolve isotopic isomers — isotopomers — and isotopologues with peak shifts dependent on the ion geometry in a manner conceptually parallel to NMR. This enables a fundamentally new approach to molecular structure characterization based on spectral isotopic shifts.