“Thermometer” Ions Can Fragment Through an Unexpected Intramolecular Elimination: These Are Not the Fragments You Are Looking For

Ieritano, Christian; Hopkins, W. Scott

doi:10.1021/acs.jpclett.1c01538

Cited by 3 publications

(6 citation statements)

References 64 publications

(84 reference statements)

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“…For the phenoxide ion, the decarboxylation process needed to go through a transition state. This cyclic transition state form has also been reported in some studies 5,31 . For the carboxylate ion, the decarboxylation reaction was an barrierless process.…”

Section: Resultssupporting

confidence: 80%

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Structural insights into variation of intramolecular acid site using phase transition experiments and computation

Fu,

Wang,

Wang

et al. 2023

AIChE Journal

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Mass transfer from liquid to gas phase is a crucial process in chemical engineering. Due to the heterogeneity and dynamic nature of the phase transition process, monitoring the structural changes of compounds during this process is challenging. In this work, a combining of the mass spectrometry‐based method and quantum chemistry calculations was used to study the structural changes during liquid‐to‐gas phase transitions. Electrospray is used to induce the transition of phenolic acid molecules from the liquid phase to the gas phase. The deprotonated structures were captured and separated using ion mobility mass spectrometry. Deprotonated structures helped to identify the most acidic functional group within the molecule. These deprotonated structures were confirmed by collision‐induced dissociation and molecular collision cross‐section measurements. Quantum chemistry calculations revealed the mechanisms about the variation of intramolecular acid site and “kinetic trapping.” Three liquid‐to‐gas phase transformation models were proposed, demonstrating that the variation in free energy among different deprotonated structures governs the thermodynamic/kinetic process of the liquid‐to‐gas phase conversion.

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Section: Resultssupporting

confidence: 80%

“…This cyclic transition state form has also been reported in some studies. 5,31 For the carboxylate ion, the decarboxylation reaction was an barrierless process.…”

Section: Different Cid Spectra Of Deprotonated Structuresmentioning

confidence: 99%

Structural insights into variation of intramolecular acid site using phase transition experiments and computation

Fu,

Wang,

Wang

et al. 2023

AIChE Journal

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“…This yields a more stable fragment and shows a comparable barrier as the earlier proposed McLafferty rearrangement (Δ G a ⌀,‡ = 136.5 kJ/mol vs Δ G b ⌀,‡ = 133.5 kJ/mol). Interestingly, the same rearrangement was recently found for an alternative class of thermometer ions studied in FAIMS …”

Section: Resultssupporting

confidence: 80%

“…Interestingly, the same rearrangement was recently found for an alternative class of thermometer ions studied in FAIMS. 82 2b can subsequently interconvert to 2a (Δ G ⌀,‡ = 185.8 kJ/mol) for further fragmentation to 3 . While these barriers might seem high, the ion temperatures at high reduced field strengths largely exceed the background gas temperature, rendering these mechanisms feasible.…”

Section: Resultsmentioning

confidence: 99%

On the Arrival Time Distribution of Reacting Systems in Ion Mobility Spectrometry

Haack,

Schaefer,

Zimmermann

2024

Anal. Chem.

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Ion mobility spectrometry (IMS) is a widely used gas-phase separation technique, particularly when coupled with mass spectrometry (MS). Modern IMS instruments often apply elevated reduced field strengths for improved ion separation and ion focusing. These alter the collision dynamics and further drive ion reaction processes that can change the analyte's structure. As a result, the measured arrival time distribution (ATD) can change with the applied reduced field strengths. In this work, we systematically study how the ion collision dynamics and the ion reaction dynamics, as a function of the reduced field strength, can alter the ATD. To this end, we investigate 2,6-di-tert-butylpyridine, methanol, and ethyl acetate using a home-built drift tube IMS coupled to a homebuilt MS and extensive first-principles Monte Carlo modeling. We show how elevated reduced field strengths can actually lower resolving power through increased ion diffusion and how the field dependency of the ion mobility can introduce uncertainties to collision cross sections (CCS) calculated from the measured mobilities. On top of the collision dynamics, we show how chemical transformation processes that alter the analyte's CCS, e.g., dynamic clustering or fragmentation, can lead to broadened, shifted, or non-Gaussian ATDs and how sensitive these processes are to the applied field strengths. We highlight how first-principles ion dynamics simulations can help to understand and even harness the mentioned effects.

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“…Several other minor fragments ions originate from [Δ 8 -THC + Ag] + , such as m/z 271, which fragments to m/z 231 via an intramolecular elimination that is reminiscent of the β-hydride abstraction of certain benzylpyridinium ions (Figures S7 and S8). 61 This is contrary to the product ion spectrum of [CBC + Ag] + , where the m/z 231 species dominates, indicating that it must be more stable relative to the m/z 231 fragment produced from [Δ 8 /Δ 9 -THC + Ag] + , and thus, must also exhibit a different structure.…”

Section: ■ Introductionmentioning

confidence: 93%

Argentination: A Silver Bullet for Cannabinoid Separation by Differential Mobility Spectrometry

2023

Self Cite

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As the legality of cannabis continues to evolve globally, there is a growing demand for methods that can accurately quantitate cannabinoids found in commercial products. However, the isobaric nature of many cannabinoids, along with variations in extraction methods and product formulations, makes cannabinoid quantitation by mass spectrometry (MS) challenging. Here, we demonstrate that differential mobility spectrometry (DMS) and tandem-MS can distinguish a set of seven cannabinoids, five of which are isobaric: Δ 9 -tetrahydrocannabinol (Δ 9 -THC), Δ 8 -THC, exo-THC, cannabidiol, cannabichromene, cannabinol, and cannabigerol. Analytes were detected as argentinated species ([M + Ag] + ), which, when subjected to collision-induced dissociation, led to the unexpected discovery that argentination promotes distinct fragmentation patterns for each cannabinoid. The unique fragment ions formed were rationalized by discerning fragmentation mechanisms that follow each cannabinoid's MS 3 behavior. The differing fragmentation behaviors between species suggest that argentination can distinguish cannabinoids by tandem-MS, although not quantitatively as some cannabinoids produce small amounts of a fragment ion that is isobaric with the major fragment generated by another cannabinoid. By adding DMS to the tandem-MS workflow, it becomes possible to resolve each cannabinoid in a pure N 2 environment by deconvoluting the contribution of each cannabinoid to a specific fragmentation channel. To this end, we used DMS in conjunction with a multiple reaction monitoring workflow to assess cannabinoid levels in two cannabis extracts. Our methodology exhibited excellent accuracy, limits of detection (10−20 ppb depending on the cannabinoid), and linearity during quantitation by standard addition (R 2 > 0.99).

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“Thermometer” Ions Can Fragment Through an Unexpected Intramolecular Elimination: These Are Not the Fragments You Are Looking For

Cited by 3 publications

References 64 publications

Structural insights into variation of intramolecular acid site using phase transition experiments and computation

Structural insights into variation of intramolecular acid site using phase transition experiments and computation

On the Arrival Time Distribution of Reacting Systems in Ion Mobility Spectrometry

Argentination: A Silver Bullet for Cannabinoid Separation by Differential Mobility Spectrometry

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