A comparison of electron ionization mass spectra obtained at 70 eV, low electron energies, and with cold EI and their NIST library identification probabilities

Eren, Ksenia J. Margolin; Elkabets, Oneg; Amirav, Aviv

doi:10.1002/jms.4646

Cited by 25 publications

(42 citation statements)

References 28 publications

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“…Cold EI typically provides higher NIST library identification probabilities due to its enhanced molecular ion as explained in details in previous studies. 23,24 As immediately observed, very large number of cannabinoid compounds are exhibited in Figure 4. We counted more than 50 cannabinoids in this complex Cannabis mixture, and each provided a distinct and rich Cold EI mass spectrum with abundant molecular ions, and several of these compounds could be identified by the NIST library at the isomer level.…”

Section: Resultsmentioning

confidence: 58%

“…GC-MS with Cold EI provides uniform compound-independent response that enables quantitation without compound-specific calibration and provides enhanced molecular ions, yet with effective NIST library-based sample identification. 23,24 Accordingly, the main attribute of GC-MS with Cold EI for cannabis analysis is its ability to perform universal untargeted analysis of all the vaporizable compounds and obtain their concentrations this way. Furthermore, we have described and demonstrated the following: a.…”

Section: Discussionmentioning

confidence: 99%

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Cannabis and its cannabinoids analysis by gas chromatography–mass spectrometry with Cold EI

et al. 2021

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Cannabis extracts and products were analyzed by gas chromatography-mass spectrometry (GC-MS) with Cold EI for their full content including terpenes, sesquiterpenes, sesquiterpinols, fatty acids, delta 9-tetrahydrocannabinol (THC), cannabidiol (CBD), other cannabinoids, hydrocarbons, sterols, diglycerides, triglycerides, and impurities. GC-MS with Cold EI is based on interfacing GC and MS with supersonic molecular beams (SMB) along with electron ionization of vibrationally cold sample compounds in the SMB in a fly-through ion source (hence the name Cold EI). GC-MS with Cold EI improves all the performance aspects of GC-MS, enables the analysis of Cannabinoids with OH groups without derivatization, while providing enhanced molecular ions for improved identification, and enables internal quantitation without calibration. We found over 50 cannabinoid compounds including a new one with a Cold EI mass spectrum very similar to delta 9-THC as well as relatively large cannabinoids with molecular weight above m/z = 400. Because the analysis was universal in full scan and not targeted, we found impurities such as bromo CBD and fluticasone propionate and could monitor the formation of oxidized CBD during decarboxylation. In addition, GC-MS with Cold EI enabled nontargeted full analysis of terpenes, sesquiterpenes, and sesquiterpinols in cannabis extracts with good internal quantitation. GC-MS with Cold EI further served with very good sensitivity for the concentration determination of delta 9-THC in CBD-related products. Finally, cannabis drugs such as EP-1 used in Israel for treatment of epilepsy and for children with autism spectrum disorder (ASD) were analyzed for their full cannabinoids content for learning on the entourage effect and for drug activity optimization.cannabinoids, cannabis, Cold EI, GC-MS, GC-MS with Cold EI, supersonic molecular beams | INTRODUCTION AND BACKGROUNDCannabis-based drugs and products are becoming more popular for treatment of a variety of diseases and disorders. One of the most promising fields is moderating phenomena such as repetitive behavior, echolalia, and self-stimulatory behavior among children with autism spectrum disorder (ASD). Most of the cannabis products are plant extracts in oil, and thus, their analysis is an area of fast-growing popularity.Gas chromatography-mass spectrometry (GC-MS) with standard EI serves mostly for terpenes analysis as well as for pesticides analysis, whereas LC-UV and/or LC-MS serve for target cannabinoids

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Section: Resultsmentioning

confidence: 58%

Section: Discussionmentioning

confidence: 99%

Cannabis and its cannabinoids analysis by gas chromatography–mass spectrometry with Cold EI

et al. 2021

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“…Figure 1 is not unusual, and it demonstrates how cold EI is far superior to standard EI, low eV EI, and PI in the mass spectral information provided. Reference ( 9 ) exhibits and describes 46 other examples of compounds from several different compound classes analyzed by cold EI in comparison with both 70 eV standard EI and low eV EI.…”

Section: Resultsmentioning

confidence: 99%

“…We also developed the Tal-Aviv Molecule Identifier (TAMI) software that inverts the molecular ion isotope abundance patterns into elemental formulas. 7 , 8 The standard EI and low eV EI experiments described below were performed with an Agilent 7890 GC and 5977 MS using 70 or 14 eV electron energies and other conditions as described in ref ( 9 ). GC-MS experiments with photoionization were performed with a Varian 1200 GC-MS (Varian Inc. Walnut Creek, CA, USA) that was modified to incorporate a photoionization ion source based on a deuterium discharge vacuum UV lamp, as described in ref ( 10 ).…”

Section: Methodsmentioning

confidence: 99%

Cold Electron Ionization (EI) Is Not a Supplementary Ion Source to Standard EI. It is a Highly Superior Replacement Ion Source

Amirav

Fialkov

Gordin

et al. 2021

J. Am. Soc. Mass Spectrom.

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GC-MS usually employs a 70 eV electron ionization (EI) ion source, which provides mass spectra with detailed fragment ion information that are amenable for library search and identification with names and structures at the isomer level. However, conventional EI often suffers from low intensity or the absence of molecular ions, which reduces detection and identification capabilities in analyses. In an attempt to enhance the molecular ions, several softer ion sources are being used to supplement standard EI, including chemical ionization (CI), atmospheric pressure chemical ionization (APCI), field ionization (FI), photoionization (PI), and low electron energy EI. However, the most advantageous way to enhance molecular ions is to use cold EI, which employs 70 eV EI of cold molecules in supersonic molecular beams. Cold EI yields classical EI mass spectra with highly enhanced molecular ions, which still provides high detectability and library-searchable mass spectra. In this paper, we explain and discuss why cold EI is not a supplementary ion source to standard EI, but rather it is a highly superior replacement to standard EI. With cold EI, there is no need for standard EI or any other supplemental ion source. We describe 16 benefits and unique features of cold EI that not only yield better results for existing applications but also significantly extend the range of compounds and applications amenable for GC-MS analysis.

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“…Furthermore, scan time has a significant impact of fidelity of isotopic abundance (16) and specific chemical gas-phase reactions in the trap (17) can lead to Orbitrap system-specific spectra. In addition, it is known that spectra are source-dependent, even at standardized 70 eV (18). These additional information are needed to be overlooked when matching to LR-[EI+]-MS spectra and entail discrepancy to current spectral predictions and substructure characterizations.…”

Section: Introductionmentioning

confidence: 99%

Open, High-Resolution EI+ Spectral Library of Anthropogenic Compounds

Price

Palát

Coufalíková

et al. 2021

Front. Public Health

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To address the lack of high-resolution electron ionisation mass spectral libraries (HR-[EI+]-MS) for environmental chemicals, a retention-indexed HR-[EI+]-MS library has been constructed following analysis of authentic compounds via GC-Orbitrap MS. The library is freely provided alongside a compound database of predicted physicochemical properties. Currently, the library contains over 350 compounds from 56 compound classes and includes a range of legacy and emerging contaminants. The RECETOX Exposome HR-[EI+]-MS library expands the number of freely available resources for use in full-scan chemical exposure studies and is available at: https://doi.org/10.5281/zenodo.4471217.

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A comparison of electron ionization mass spectra obtained at 70 eV, low electron energies, and with cold EI and their NIST library identification probabilities

Cited by 25 publications

References 28 publications

Cannabis and its cannabinoids analysis by gas chromatography–mass spectrometry with Cold EI

Cannabis and its cannabinoids analysis by gas chromatography–mass spectrometry with Cold EI

Cold Electron Ionization (EI) Is Not a Supplementary Ion Source to Standard EI. It is a Highly Superior Replacement Ion Source

Open, High-Resolution EI+ Spectral Library of Anthropogenic Compounds

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