Ion mobility spectrometer—field asymmetric ion mobility spectrometer-mass spectrometry

摘要

Since the development of electrospray ionization (ESI) for ion mobility spectrometry mass spectrometry (IMMS), IMMS have been extensively applied for characterization of gas-phase bio-molecules. Conventional ion mobility spectrometry (IMS), defined as drift tube IMS (DT-IMS), is typically a stacked ring design that utilizes a low electric field gradient. Field asymmetric ion mobility spectrometry (FAIMS) is a newer version of IMS, however, the geometry of the system is significantly different than DT-IMS and data are collected using a much higher electric field. Here we report construction of a novel ambient pressure dual gate DT-IMS coupled with a FAIMS system and then coupled to a quadrupole ion trap mass spectrometer (QITMS) to form a hybrid three-dimensional separation instrument, DT-IMS-FAIMS-QITMS. The DT-IMS was operated at ~3 Townsend (electric fieldumber density (E/N) or (Td)) and was coupled in series with a FAIMS, operated at ~80 Td. Ions were mobility-selected by the dual gate DT-IMS into the FAIMS and from the FAIMS the ions were detected by the QITMS for as either MS or MSn. The system was evaluated using cocaine as an analytical standard and tested for the application of separating three isomeric tri-peptides: tyrosine-glycine-tryptophan (YGW), tryptophan-glycine-tyrosine (WGY) and tyrosine-tryptophan-glycine (YWG). All three tri-peptides were separated in the DT-IMS dimension and each had one mobility peak. The samples were partially separated in the FAIMS dimension but two conformation peaks were detected for the YWG sample while YGW and WGY produced only one peak. Ion validation was achieved for all three samples using QITMS.