Increasing Peak Capacity in Nontargeted Omics Applications by Combining Full Scan Field Asymmetric Waveform Ion Mobility Spectrometry with Liquid Chromatography–Mass Spectrometry

Abstract

Full scan field asymmetric waveform ion mobility spectrometry (FAIMS) combined with liquid chromatography and mass spectrometry (LC-FAIMS-MS) is shown to enhance peak capacity for omics applications. A miniaturized FAIMS device capable of rapid compensation field scanning has been incorporated into an ultrahigh performance liquid chromatography (UHPLC) and time-of-flight mass spectrometry analysis, allowing the acquisition of full scan FAIMS and MS nested data sets within the time scale of a UHPLC peak. Proof of principle for the potential of scanning LC-FAIMS-MS in omics applications is demonstrated for the nontargeted profiling of human urine using a HILIC column. The high level of orthogonality between FAIMS and MS provides additional unique compound identifiers with detection of features based on retention time, FAIMS dispersion field and compensation field (DF and CF), and mass-to-charge (m/z). Extracted FAIMS full scan data can be matched to standards to aid the identification of unknown analytes. The peak capacity for features detected in human urine using LC-FAIMS-MS was increased approximately threefold compared to LC-MS alone due to a combination of the reduction of chemical noise and separation of coeluting isobaric species across the entire analytical space. The use of FAIMS-selected in source collision induced dissociation (FISCID) yields fragmentation of ions, which reduces sample complexity associated with overlapping fragmentation patterns and provides structural information on the selected precursor ions.

Combined hydrophilic interaction liquid chromatography-scanning field asymmetric waveform ion mobility spectrometry-time-of-flight mass spectrometry for untargeted metabolomics

“…Ion mobility separation was carried out at ambient pressure using a multichannel ultraFAIMS device with a 100-μm electrode gap, 78.1 mm trench length (span), and 700 μm ion path length [27]. The full CF range consisting of 19 steps from − 0.5 to 3.5 Td was acquired at rate 1 scan s −1 , at a fixed DF of 240 Td, suitable for metabolomics studies [25]. The FAIMS device was controlled by the prototype software FAIMS Control (Agilent Technologies, Santa Clara, USA).…”

“…The slow scan speed of the device did not allow the full CF range to be scanned within the timescale of an LC peak, so the FAIMS was stepped between six selected CFs, providing partial coverage of the metabolome. The hyphenation of hydrophilic interaction liquid chromatography (HILIC) with FAIMS-MS, using a miniaturised FAIMS device, was reported by Arthur et al [25], where a detailed comparison of the HILIC-MS and HILIC-FAIMS-MS analysis of urine showed that FAIMS integration into the analysis significantly increased the number of molecular features detected using 11 CF steps. Recently, Wernish et al [26] have published a study in which they analysed a mixture of more than 800 metabolites by 7 different chromatography columns.…”

Ion Mobility Spectrometry in Food Analysis: Principles, Current Applications and Future Trends

“…In this context, the integration of IMS in LC–MS workflows introduces a third separation dimension that improves peak capacity and allows the separation of isobars and isomers [33]. The implementation of IMS in LC–MS workflows increase peak capacity at least 2 or 3-fold [34,35], although this improvement ultimately depends on IMS resolution and the analytical application. Moreover, chromatographic peaks are extracted from background noise which provides cleaned-up chromatograms and mass spectra, leading to an improvement of the limits of detection (LODs) and sensitivity.…”

Adding a new separation dimension to MS and LC–MS: What is the utility of ion mobility spectrometry?

“…Other notable recent studies have focused on nontargeted metabolomic assessment of placental samples , and serum profiling . The potential of LC–FAIMS–MS was also explored in a very recent contribution with a broad outlook toward different “omics” approaches .…”