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Rowell CER, Kaur J, Zhang Y, Alzarieni KZ, Anyaeche RO, Ma HM, Little AM, Sharma T, Nussbaum MD, Hershberger DA, Lee YJ, Blagojevic V, Neill JL, Kenttämaa HI. Application of Laser-Induced Acoustic Desorption for Molecular Rotational Resonance Spectroscopy. Anal Chem 2024; 96:6255-6263. [PMID: 38588398 DOI: 10.1021/acs.analchem.3c05486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/10/2024]
Abstract
Molecular Rotational Resonance (MRR) spectroscopy is a uniquely precise tool for the determination of molecular structures of volatile compounds in mixtures, as the characteristic rotational transition frequencies of a molecule are extremely sensitive to its 3D structure through the moments of inertia in a three-dimensional coordinate system. This enables identification of the compounds based on just a few parameters that can be calculated, as opposed to, for example, mass spectrometric data, which often require expert analysis of 10-20 different signals and the use of many standards/model compounds. This paper introduces a new sampling technique for MRR, laser-induced acoustic desorption (LIAD), to allow the vaporization of nonvolatile and thermally labile analytes without the need for excessive heating or derivatization. In this proof-of-concept study, LIAD was successfully coupled to an MRR instrument to conduct measurements on seven compounds with differing polarities, molecular weights, and melting and boiling points. Identification of three isomers in a mixture was also successfully performed using LIAD/MRR. Based on these results, LIAD/MRR is demonstrated to provide a powerful approach for the identification of nonvolatile and/or thermally labile analytes with molecular weights up to 600 Da in simple mixtures, which does not require the use of reference compounds. In the future, applications to more complex mixtures, such as those relevant to pharmaceutical research, and quantitative aspects of LIAD/MRR will be reported.
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Affiliation(s)
- Caroline E R Rowell
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Jaskiran Kaur
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Yuyang Zhang
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Kawthar Z Alzarieni
- Jordan University of Science and Technology, Faculty of Pharmacy, Department of Medicinal Chemistry and Pharmacognosy, Irbid 22110, Jordan
| | - Ruth O Anyaeche
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Hendrik M Ma
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Annika M Little
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Tanya Sharma
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Matthan D Nussbaum
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Drake A Hershberger
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | - Ying-Jou Lee
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
| | | | - Justin L Neill
- BrightSpec Inc., Charlottesville, Virginia 22903, United States
| | - Hilkka I Kenttämaa
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47904, United States
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Zhang B, Burchill L, Altalhi WAO, Ma HZ, O'Hair RAJ. A fixed-charge model of the N-protomer of 4-aminobenzoic acid to facilitate the study of the unimolecular and bimolecular chemistry of its "neutral" carboxylic acid group. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2024; 38:e9681. [PMID: 38355884 DOI: 10.1002/rcm.9681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 11/24/2023] [Accepted: 11/25/2023] [Indexed: 02/16/2024]
Abstract
RATIONALE There are a growing number of examples of protomers formed via electrospray ionization (ESI) that do not fragment under mobile proton conditions, giving rise to distinct tandem mass spectra. To model the N-protomer of 4-aminobenzoic acid, here we study the gas-phase unimolecular and bimolecular chemistry of the 4-(carboxyphenyl)trimethylammonium ion. METHODS 4-(Carboxyphenyl)trimethylammonium iodide was synthesized, purified via recrystallization and transferred to the gas phase via ESI. 4-(Carboxyphenyl)trimethylammonium ion, 7, was mass selected and subjected to collision-induced dissociation and ion-molecule reactions in a linear ion trap mass spectrometer. RESULTS The major fragmentation channel for the fixed-charge cation 7 is methyl radical loss, whereas loss of trimethylamine and CO2 represents minor pathways. The free carboxylic acid functional group of 7 is unreactive toward a number of neutral reagents (methanol, acetone, acetonitrile, and N,N'-diisopropylcarbodiimide). 7 reacts very slowly with trimethylborate via addition-elimination, consistent with density functional theory (DFT) calculations that show this reaction is slightly endothermic. The deuterated cation 7(D) undergoes slow D/H exchange with ethanol, and DFT calculations reveal that a flip-flop mechanism operates. CONCLUSIONS The free carboxylic group of 7 is not very reactive toward neutral reagents in the gas phase.
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Affiliation(s)
- Beiang Zhang
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Laura Burchill
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Weam A O Altalhi
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- Department of Chemistry, Prince Sattam Bin Abdulaziz University, Hotat Bani Tamim, Saudi Arabia
| | - Howard Z Ma
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Richard A J O'Hair
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
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3
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Shen S, Chai Y, Feng H, Chen Y, Pan Y. Gas-Phase Alcoholysis of Benzylic Halides in the Atmospheric Pressure Ionization Source. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:178-184. [PMID: 38165091 DOI: 10.1021/jasms.3c00203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
The present study investigates the gas-phase alcoholysis reaction of benzylic halides under atmospheric pressure chemical ionization (APCI) conditions. The APCI corona discharge is used to initiate the novel reaction, which is monitored by ion trap mass spectrometry (IT-MS). The model compound α,α,α-trifluorotoluene is applied to observe the cascade methoxylation reaction during the +APCI-MS analysis, resulting in the formation of [PhC(OCH3)2]+. Based on the results of isotopic labeling and substrate expansion experiments, an addition-elimination mechanism is proposed: initially, the reaction was initiated by the dissociation of fluorine from PhCF3 under APCI condition, leading to the formation of [PhCF2]+; subsequently, two methanol molecules nucleophilicly attack [PhCF2]+ stepwisely, accompanied by the elimination of HF, yielding the product ion [PhC(OCH3)2]+. The proposed mechanism was further corroborated by theoretical calculations. The results of substrate scope expansion experiments suggest that this in-source reaction has the potential to differentiate the positional isomers of alcohols and phenols.
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Affiliation(s)
- Shanshan Shen
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
- Zhejiang Institute for Food and Drug Control, Key Laboratory of Drug Contacting Materials Quality Control of Zhejiang Province, Hangzhou 310052, China
| | - Yunfeng Chai
- Tea Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310008, China
| | - Hongru Feng
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
| | - Yue Chen
- Zhejiang Institute for Food and Drug Control, Key Laboratory of Drug Contacting Materials Quality Control of Zhejiang Province, Hangzhou 310052, China
| | - Yuanjiang Pan
- Department of Chemistry, Zhejiang University, Hangzhou 310027, China
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Parker K, Bollis NE, Ryzhov V. Ion-molecule reactions of mass-selected ions. MASS SPECTROMETRY REVIEWS 2024; 43:47-89. [PMID: 36447431 DOI: 10.1002/mas.21819] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Gas-phase reactions of mass-selected ions with neutrals covers a very broad area of fundamental and applied mass spectrometry (MS). Oftentimes, ion-molecule reactions (IMR) can serve as a viable alternative to collision-induced dissociation and other ion dissociation techniques when using tandem MS. This review focuses on the literature pertaining applications of IMR since 2013. During the past decade considerable efforts have been made in analytical applications of IMR, including advances in one of the major techniques for characterization of unsaturated fatty acids and lipids, ozone-induced dissociation, and the development of a new technique for sequencing of large ions, hydrogen atom attachment/abstraction dissociation. Many advances have also been made in identifying gas-phase chemistry specific to a functional group in organic and biological compounds, which are useful in structure elucidation of analytes and differentiation of isomers/isobars. With "soft" ionization techniques like electrospray ionization having become mainstream for quite some time now, the efforts in the area of metal ion catalysis have firmly moved into exploring chemistry of ligated metal complexes in their "natural" oxidation states allowing to model individual steps of mechanisms in homogeneous catalysis, especially in combination with high-level DFT calculations. Finally, IMR continue to contribute to the body of knowledge in the area of chemistry of interstellar processes.
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Affiliation(s)
- Kevin Parker
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois, USA
| | - Nicholas E Bollis
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois, USA
| | - Victor Ryzhov
- Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, Illinois, USA
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Ma X. Recent Advances in Mass Spectrometry-Based Structural Elucidation Techniques. Molecules 2022; 27:molecules27196466. [PMID: 36235003 PMCID: PMC9572214 DOI: 10.3390/molecules27196466] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/23/2022] [Accepted: 09/26/2022] [Indexed: 11/17/2022] Open
Abstract
Mass spectrometry (MS) has become the central technique that is extensively used for the analysis of molecular structures of unknown compounds in the gas phase. It manipulates the molecules by converting them into ions using various ionization sources. With high-resolution MS, accurate molecular weights (MW) of the intact molecular ions can be measured so that they can be assigned a molecular formula with high confidence. Furthermore, the application of tandem MS has enabled detailed structural characterization by breaking the intact molecular ions and protonated or deprotonated molecules into key fragment ions. This approach is not only used for the structural elucidation of small molecules (MW < 2000 Da), but also crucial biopolymers such as proteins and polypeptides; therefore, MS has been extensively used in multiomics studies for revealing the structures and functions of important biomolecules and their interactions with each other. The high sensitivity of MS has enabled the analysis of low-level analytes in complex matrices. It is also a versatile technique that can be coupled with separation techniques, including chromatography and ion mobility, and many other analytical instruments such as NMR. In this review, we aim to focus on the technical advances of MS-based structural elucidation methods over the past five years, and provide an overview of their applications in complex mixture analysis. We hope this review can be of interest for a wide range of audiences who may not have extensive experience in MS-based techniques.
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Affiliation(s)
- Xin Ma
- School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Dr NW, Atlanta, GA 30332, USA
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Liu JKY, Feng E, Fu Y, Li W, Ma X, Sheng H, Kong J, Liu Y, Hicks M, Xiang B, Liu Z, Pennington J, Kenttämaa HI. A Diagnostic Nitrosamine Detection Approach for Pharmaceuticals by Using Tandem Mass Spectrometry Based on Diagnostic Gas-Phase Ion-Molecule Reactions. Anal Chem 2022; 94:13795-13803. [PMID: 36154017 DOI: 10.1021/acs.analchem.2c02282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
N-Nitrosamines are strictly regulated in pharmaceutical products due to their carcinogenic nature. Therefore, the ability to rapidly and reliably identify the N-nitroso functionality is urgently needed. Unfortunately, not all ionized N-nitroso compounds produce diagnostic fragment ions and hence tandem mass spectrometry based on collision-activated dissociation (CAD) cannot be used to consistently identify the N-nitroso functionality. Therefore, a more reliable method was developed based on diagnostic functional-group selective ion-molecule reactions in a linear quadrupole ion trap mass spectrometer. 2-Methoxypropene (MOP) was identified as a reagent that reacts with protonated N-nitrosamines in a diagnostic manner by forming an adduct followed by the elimination of 2-propenol (CH3C(OH)═CH2]). From 18 protonated N-nitrosamine model compounds studied, 15 formed the diagnostic product ion. The lack of the diagnostic reaction for three of the N-nitrosamine model compounds was rationalized based on the presence of a pyridine ring that gets preferentially protonated instead of the N-nitroso functionality. These N-nitrosamines can be identified by subjecting a stable adduct formed upon ion-molecule reactions with MOP to CAD. Further, the ability to use ion-molecule reactions followed by CAD to differentiate protonated O-nitroso compounds with a pyridine ring from analogous N-nitrosamines was demonstrated This methodology is considered to be robust for the identification of the N-nitroso functionality in unknown analytes. Lastly, HPLC/MS2 experiments were performed to determine the detection limit for five FDA regulated N-nitrosamines.
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Affiliation(s)
- Judy Kuan-Yu Liu
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Erlu Feng
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Yue Fu
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Wanru Li
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Xin Ma
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Huaming Sheng
- Department of Analytical Research & Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - John Kong
- Department of Analytical Research & Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Yong Liu
- Department of Analytical Research & Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Michael Hicks
- Department of Analytical Research & Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Bangping Xiang
- Department of Analytical Research & Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Zhijian Liu
- Department of Analytical Research & Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Justin Pennington
- Department of Analytical Research & Development, Merck & Co., Inc., Rahway, New Jersey 07065, United States
| | - Hilkka I Kenttämaa
- Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, United States
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Corinti D, Chiavarino B, Spano M, Tintaru A, Fornarini S, Crestoni ME. Molecular Basis for the Remarkably Different Gas-Phase Behavior of Deprotonated Thyroid Hormones Triiodothyronine (T3) and Reverse Triiodothyronine (rT3): A Clue for Their Discrimination? Anal Chem 2021; 93:14869-14877. [PMID: 34714056 PMCID: PMC8581966 DOI: 10.1021/acs.analchem.1c03892] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
![]()
Thyroid hormones
are biologically active small molecules responsible
for growth and development regulation, basal metabolic rate, and lipid
and carbohydrate metabolism. Liquid chromatography mass spectrometry
(LC–MS) can be used to quantify thyroid hormones blood level
with high speed and selectivity, aiming to improve the diagnosis and
treatment of the severe pathological conditions in which they are
implicated, i.e., hypo- and hyperthyroidism. In this work, the gas-phase
behavior of the isomeric thyroid hormones triiodothyronine (T3) and
reverse triiodothyronine (rT3) in their deprotonated form was studied
at a molecular level using MS-based techniques. Previously reported
collision-induced dissociation experiments yielded distinct spectra
despite the high structural similarity of the two compounds, suggesting
different charge sites to be responsible. Infrared multiple photon
dissociation spectroscopy on [T3-H]− and [rT3-H]− was performed, and the results were interpreted using
DFT and MP2 calculations, assessing the prevalence of T3 in the carboxylate
form and rT3 as a phenolate isomer. The different deprotonation sites
of the two isomers were also found to drive their ion-mobility behavior.
In fact, [T3-H]− and [rT3-H]− were
successfully separated. Drift times were correlated with collisional
cross section values of 209 and 215 Å2 for [T3-H]− and [rT3-H]−, respectively. Calculations
suggested the charge site to be the main parameter involved in the
different mobilities of the two anions. Finally, bare [T3-H]− and [rT3-H]− were made to react with neutral acetylacetone
and trifluoroacetic acid, confirming rT3 to be more acidic than T3
in agreement with the calculated gas-phase acidities of T3 and rT3
equal to 1345 and 1326 kJ mol–1, respectively.
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Affiliation(s)
- Davide Corinti
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma "La Sapienza", Roma I-00185, Italy
| | - Barbara Chiavarino
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma "La Sapienza", Roma I-00185, Italy
| | - Mattia Spano
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma "La Sapienza", Roma I-00185, Italy
| | - Aura Tintaru
- Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire, UMR 7273, Marseille 13397, France
| | - Simonetta Fornarini
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma "La Sapienza", Roma I-00185, Italy
| | - Maria Elisa Crestoni
- Dipartimento di Chimica e Tecnologie del Farmaco, Università di Roma "La Sapienza", Roma I-00185, Italy
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