Field Induced Fragmentation (Fif) Spectra of Oxygen Containing Volatile Organic Compounds with Reactive Stage Tandem Ion Mobility Spectrometry and Functional Group Classification by Neural Network Analysis

Abstract

Mobility isolated spectra were obtained for protonated monomers of 42 volatile oxygen containing organic compounds at ambient pressure using a tandem ion mobility spectrometer with a reactive stage between drift regions. Fragment ions of protonated monomers of alcohols, acetates, aldehydes, ketones, and ethers were produced in the reactive stage using a 3.3 MHz symmetrical sinusoidal waveform with an amplitude of 1.4 kV and mobility analyzed in a 19 mm long drift region. The resultant field induced fragmentation (FIF) spectra included residual intensities for protonated monomers and fragment ions with characteristic drift times and peak intensities, associated with ion mass and chemical class. High efficiency of fragmentation was observed with single bond cleavage of alcohols and in six-member ring rearrangements of acetates. Fragmentation was not observed, or seen weakly, with aldehydes, ethers, and ketones due to their strained four-member ring transition states. Neural networks were trained to categorize spectra by chemical class and tested with FIF spectra of both familiar and unfamiliar compounds. Rates of categorization were class dependent with best performance for alcohols and acetates, moderate performance for ketones, and worst performance for ethers and aldehydes. Trends in the rates of categorization within a chemical family can be understood as steric influences on the energy of activation for ion fragmentation. Electric fields greater than 129 Td or new designs of reactive stages with improved efficiency of fragmentation will be needed to extend the practice of reactive stage tandem IMS to an expanded selection of volatile organic compounds.

Geometric Feature Extraction of Point Cloud of Chemical Reactor Based on Dynamic Graph Convolution Neural Network

“…The precision (PRE), recall (REC), F1 score (F1,) and accuracy (ACC) are used to evaluate the results. 46 …”

“…The precision (PRE), recall (REC), F1 score (F1,) and accuracy (ACC) are used to evaluate the results. 46 The calculation formula of PRE is eq 6: where TP is a true positive case; that is, the actual case is a positive case, and the model prediction is a positive case. FP is a true negative case; that is, the actual case is a negative case, and the model prediction is a negative case.…”

Ion Mobility Mass Spectrometry for the Separation and Characterization of Small Molecules

“…Wang et al identified many components in Lanqin Oral Liquid (a Chinese patent medicine) by UPLC-IM-QTOF-MS and automatic peak annotation driven by UNIFI software. The CCS data correlation global natural products molecular networking platform (GNPS) can further identify targeted or nontargeted compounds with a high throughput. − …”

Highly Efficient Ion Manipulator for Tandem Ion Mobility Spectrometry: Exploring a Versatile Technique by a Study of Primary Alcohols

“…Shokri et al expanded on this concept by combining multistage IMS separation with a fragmenter grid operated with a high-frequency sinusoidal electric field, allowing prior mobility selection of the ions to be fragmented . It could be shown that the mobility analysis of fragments enables the identification of chemical classes via IMS . Further improvements of design and operation methods results in the highly efficient ion manipulator presented in this work.…”

“…Imparting energy into the ion-neutral system can additionally influence the equilibrium of chemical reactions and lead to cluster dissociation or even fragmentation and thus to the formation of new ion species related to the target substance . IMS systems take advantage of increased ion energies including the high kinetic energy ion mobility spectrometer (HiKE-IMS) from the study of Langejürgen et al, , the tandem IMS with field-induced fragmentation from the study of Shokri et al, − and the field asymmetric time of flight IMS (FAT-IMS) from our group − first published in 2015, which is the fundamental basis for this work. The ions’ energy, expressed as an effective temperature T eff , is according to the Wannier expression proportional to the square of the reduced electrical field strength E / N .…”