title: Pulsed Nano-ESI Atmospheric-Pressure Ion Mobility Mass Spectrometry with Enhanced Ion Sampling.
abstract: Ion mobility-mass spectrometry (IM-MS) has gained considerable attention for detection of clusters and weakly bound species created by electrospray ionization (ESI). Atmospheric-pressure (AP) IM-MS offers an advantage in these studies compared to its low-pressure counterpart, owing to soft introduction of ions into the mobility cell with minimal ion activation. Here, we report new approaches to improve the sensitivity and soft ion introduction in AP-IM-MS. For the former, we demonstrate enhanced aerodynamic sampling of ions from the mobility cell into the MS using pulsed-field sampling. In this approach, ions are driven toward the MS, and the field is shut down once the ions reach the vicinity of the MS inlet orifice. The pulsed-field operation provides arrival times without the need for an exit ion gate in the mobility cell and leads to improvements in sensitivity of up to 1 order of magnitude. For soft ion generation, we report a pulsed nano-ESI source to introduce a packet of ions into the room-temperature mobility cell without induced desolvation. Further, we demonstrate the application of the pulsed nano-ESI AP-IM-MS with enhanced ion sampling for detection of solvent clusters of amines and peptide aggregates.
authors: Department of Chemistry, Georgetown University , Washington DC 20057, United States.
authors: William P
authors: WP
authors: McMahon
authors: Department of Chemistry, Georgetown University , Washington DC 20057, United States.
authors: Arjuna
authors: A
authors: Subramanian
authors: Department of Chemistry, Georgetown University , Washington DC 20057, United States.
authors: Carina S
authors: CS
authors: Minardi
authors: Department of Chemistry, Georgetown University , Washington DC 20057, United States.
authors: Rohan
authors: R
authors: Dalvi
authors: Department of Chemistry, Georgetown University , Washington DC 20057, United States.
authors: Kaveh
authors: K
authors: Jorabchi