Considerations in experimental and theoretical collision cross-section measurements of small molecules using travelling wave ion mobility spectrometry-mass spectrometry

摘要: Abstract Travelling wave ion mobility spectrometry-mass spectrometry (TWIMS-MS) has the capability to separate ions based on their through a gas-filled travelling (T-wave) device in presence of train transient voltage pulses. By calibration this using analytes previously determined cross-sectional area (from conventional IMS experiments), collision cross-sections can be drift time T-wave device. Comparison experimentally with theoretical calculations from structural models potential provide methodology which applied uncharacterised structure; however, comparison relies high degree confidence both experimental and methods. Focussing small (≤200 Da) molecules, have been measured by TWIMS-MS employing procedure that uses oligo-glycine peptides human haemoglobin-derived tryptic order extend range for measurement ions. The effect TWIMS height parameters is addressed. Theoretical cross-section performed rapid, Windows-based, in-house developed projection approximation algorithm. These estimates were optimised values series molecules rigid core structures systematic variation interaction radii atoms comprising these species until measurements agreement derived cross-sections. varying radius buffer gas was subsequently studied calculated helium nitrogen either or gases. It found used should ideally match calibrants originally IMS. resolving demonstrated separation two isomeric amino acids, leucine isoleucine, showed