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Gutiérrez-Quintanilla A, Moge B, Compagnon I, Noble JA. Vibrational and electronic spectra of protonated vanillin: exploring protonation sites and isomerisation. Phys Chem Chem Phys 2024; 26:15358-15368. [PMID: 38767194 DOI: 10.1039/d3cp05573f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Photofragmentation spectra of protonated vanillin produced under electrospray ionisation (ESI) conditions have been recorded in the 3000-3700 cm-1 (vibrational) and 225-460 nm (electronic) ranges, using room temperature IRMPD (infrared multiphoton dissociation) and cryogenic UVPD (ultraviolet photodissociation) spectroscopies, respectively. The cold (∼50 K) electronic UVPD spectrum exhibits very well resolved vibrational structure for the S1 ← S0 and S3 ← S0 transitions, suggesting long excited state dynamics, similar to its simplest analogue, protonated benzaldehyde. The experimental data were combined with theoretical calculations to determine the protonation site and configurational isomer observed in the experiments.
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Affiliation(s)
- Alejandro Gutiérrez-Quintanilla
- CNRS, Aix Marseille Univ., PIIM, Physique des Interactions Ioniques et Moléculaires, UMR 7345, 13397 Marseille, France.
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France
| | - Baptiste Moge
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - Isabelle Compagnon
- Univ. Lyon, Université Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, F-69622 Villeurbanne, France
| | - Jennifer A Noble
- CNRS, Aix Marseille Univ., PIIM, Physique des Interactions Ioniques et Moléculaires, UMR 7345, 13397 Marseille, France.
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2
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Feng YQ, Zhang P, Jian JZ, Wang ZW, Tian XL, Luo GY, Yang WD. Study on 2-arylbenzo[ b]furans from Itea omeiensis and their fragmentation patterns with Q-Orbitrap mass spectrometry. Nat Prod Res 2023:1-12. [PMID: 37245178 DOI: 10.1080/14786419.2023.2216344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 04/24/2023] [Accepted: 05/10/2023] [Indexed: 05/29/2023]
Abstract
One new 2-arylbenzo[b]furan named iteafuranal F (1) as well as two known analogues (2-3) were isolated from the 95% EtOH extract of aerial parts of Itea omeiensis. Their chemical structures were constructed based on extensive analyses of UV, IR, 1D/2D NMR and HRMS spectra. Antioxidant assays revealed significant superoxide anion radical scavenging capacity of 1 with IC50 value of 0.66 mg/mL, which was comparable to the efficiency of positive control of luteolin. In addition, the preliminary MS fragmentation patterns in negative ion mode were established to distinguish 2-arylbenzo[b]furans with C-10 in different oxidation states: the characteristic loss of CO molecule [M-H-28]- was observed for 3-formyl-2-arylbenzo[b]furans, and the loss of CH2O fragment [M-H-30]- for 3-hydroxymethyl-2-arylbenzo[b]furans, and the loss of CO2 fragment [M-H-44]- for 2-arylbenzo[b]furan-3-carboxylic acids.
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Affiliation(s)
- Yun-Qian Feng
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang, People's Republic of China
| | - Pan Zhang
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang, People's Republic of China
| | - Jin-Zhen Jian
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang, People's Republic of China
| | - Zhi-Wei Wang
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang, People's Republic of China
| | - Xiao-Long Tian
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang, People's Republic of China
| | - Guo-Yong Luo
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang, People's Republic of China
| | - Wu-De Yang
- School of Pharmacy, Guizhou University of Traditional Chinese Medicine, Guiyang, People's Republic of China
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Liang Y, Simón-Manso Y, Neta P, Stein SE. Unexpected Gas-Phase Nitrogen-Oxygen Smiles Rearrangement: Collision-Induced Dissociation of Deprotonated 2-( N-Methylanilino)ethanol and Morpholinylbenzoic Acid Derivatives. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:2120-2128. [PMID: 36269933 PMCID: PMC10959088 DOI: 10.1021/jasms.2c00210] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
A nitrogen-oxygen Smiles rearrangement was reported to occur after collisional activation of the PhN(R)CH2CH2O- (R = alkyl) anion, which undergoes a five-membered ring rearrangement to form a phenoxide ion C6H5O-. When R = H, such a Smiles rearrangement is unlikely since the negative charge is more favorably located on the nitrogen atom than the oxygen atom; hence, alternative neutral losses dominate the fragmentation. For example, collisional activation of deprotonated 2-anilinoethanol (PhN-CH2CH2OH) leads to the formation of an anilide anion (C6H5NH-, m/z 92) rather than a phenoxide ion (C6H5O-, m/z 93.0343). However, when the amino hydrogen of 2-anilinoethanol is substituted by a methyl group, i.e., 2-(N-methylanilino)ethanol, a Smiles rearrangement does occur, leading to the phenoxide ion, as the negative charge can only reside on the oxygen atom. To confirm the Smiles rearrangement mechanism, 2-(N-methylanilino)ethanol-18O was synthesized and subjected to collisional activation, leading to an intense peak at m/z 95.0385, which corresponds to the 18O phenoxide ion ([C6H518O]-). The abundance of the phenoxide ion is sensitive to substituents on the N atom, as demonstrated by the observation that an ethyl substituent results in the rearrangement ion with a much lower abundance. The nitrogen-oxygen Smiles rearrangement also occurs for various morpholinylbenzoic acid derivatives with a multistep mechanism, where the phenoxide ion is found to be predominantly formed after loss of CO2, proton transfers, breaking of the morpholine ring, and Smiles rearrangement. The Smiles mechanism is also supported by density functional theory calculations and other observations.
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Affiliation(s)
- Yuxue Liang
- Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Yamil Simón-Manso
- Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Pedatsur Neta
- Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Stephen E Stein
- Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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Kumar M, Zheng Z, Nishshanka U, Xia H, Weisbecker C, Attygalle AB. Fragmentation pathways of deprotonated ortho-hydroxybenzyl alcohol. JOURNAL OF MASS SPECTROMETRY : JMS 2022; 57:e4829. [PMID: 35581161 DOI: 10.1002/jms.4829] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 03/11/2022] [Accepted: 03/11/2022] [Indexed: 06/15/2023]
Abstract
The ortho, meta, and para isomers of hydroxybenzyl alcohol can be unequivocally distinguished by the collision-induced dissociation mass spectra of their anions. The presence of a prominent peak at m/z 121 for an elimination of a dihydrogen molecule renders the ortho-isomer spectrum markedly different from those of its meta and para congeners. Investigations carried out with deuterium-labeled isotopologues of the ortho isomer verified that the labile hydrogen atom on the hydroxyl group and one of the benzylic hydrogen atoms are specifically removed in the formation of the m/z 121 ion. The ortho-isomer spectrum also showed a prominent peak at m/z 93. Experimental data indicated that the m/z 93 product ion originates either from a two-step H2 and CO elimination mechanism or from a direct loss of a HCHO molecule from the precursor anion. The intensity ratio of the m/z 93 and 94 peaks in the spectrum recorded from the m/z 124 ion generated from a sample of o-hydroxybenzyl alcohol dissolved in D2 O supported the notion that the direct HCHO loss is the more dominant pathway for the generation of the phenolate ion under low activation conditions. In contrast, the two-step mechanism becomes the more dominant pathway under high collisional activation conditions. The spectrum also showed a weak peak at m/z 105 for a water loss. Based on computational data, the m/z 105 ion generated in this way appears to be a composite generated from a common ion-neutral complex intermediate in which a hydroxyl anion is positioned equidistantly between one of the benzylic hydrogens and a nearby hydrogen atom of the benzene ring. Upon activation, the complex dissociates to form either a phenide or a quinone methide anion. The reaction forming a carbon dioxide adduct under ion-mobility conditions was used to support the proposed water-loss mechanism.
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Affiliation(s)
- Meenu Kumar
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA
| | - Zhaoyu Zheng
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA
| | - Upul Nishshanka
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA
| | - Hanxue Xia
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA
| | - Carl Weisbecker
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA
| | - Athula B Attygalle
- Center for Mass Spectrometry, Department of Chemistry, Chemical Biology and Biomedical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, USA
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Ucur B, Maccarone AT, Ellis SR, Blanksby SJ, Trevitt AJ. Solvent-Mediated Proton-Transfer Catalysis of the Gas-Phase Isomerization of Ciprofloxacin Protomers. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:347-354. [PMID: 35014802 DOI: 10.1021/jasms.1c00331] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Understanding how neutral molecules become protonated during positive-ion electrospray ionization (ESI) mass spectrometry is critically important to ensure analytes can be efficiently ionized, detected, and unambiguously identified. The ESI solvent is one of several parameters that can alter the dominant site of protonation in polyfunctional molecules and thus, in turn, can significantly change the collision-induced dissociation (CID) mass spectra relied upon for compound identification. Ciprofloxacin─a common fluoroquinolone antibiotic─is one such example whereby positive-ion ESI can result in gas-phase [M + H]+ ions protonated at either the keto-oxygen or the piperazine-nitrogen. Here, we demonstrate that these protonation isomers (or protomers) of ciprofloxacin can be resolved by differential ion mobility spectrometry and give rise to distinctive CID mass spectra following both charge-directed and charge-remote mechanisms. Interaction of mobility-selected protomers with methanol vapor (added via the throttle gas supply) was found to irreversibly convert the piperazine N-protomer to the keto-O-protomer. This methanol-mediated proton-transport catalysis is driven by the overall exothermicity of the reaction, which is computed to favor the O-protomer by 93 kJ mol-1 (in the gas phase). Conversely, gas phase interactions of mobility-selected ions with acetonitrile vapor selectively depletes the N-protomer ion signal as formation of stable [M + H + CH3CN]+ cluster ions skews the apparent protomer population ratio, as the O-protomer is unaffected. These findings provide a mechanistic basis for tuning protomer populations to ensure faithful characterization of multifunctional molecules by tandem mass spectrometry.
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Affiliation(s)
- Boris Ucur
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Alan T Maccarone
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
| | - Shane R Ellis
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
- Illawarra Health and Medical Research Institute, Wollongong, New South Wales 2522, Australia
| | - Stephen J Blanksby
- Central Analytical Research Facility and School of Chemistry and Physics, Queensland University of Technology, Brisbane 4001, Australia
| | - Adam J Trevitt
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, New South Wales 2522, Australia
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Liang Y, Simón-Manso Y, Neta P, Yang X, Stein SE. CID Fragmentation of Deprotonated N-Acyl Aromatic Sulfonamides. Smiles-Type and Nitrogen-Oxygen Rearrangements. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:806-814. [PMID: 33586949 DOI: 10.1021/jasms.0c00470] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The NIST tandem mass spectral library (2020 version) includes over 800 aromatic sulfonamides. In negative mode, upon collisional activation most benzenesulfonamides lose a neutral SO2 molecule leading to an anilide anion (C6H5NH-, m/z 92). However, for deprotonated N-benzoyl aromatic sulfonamides, the phenoxide ion (C6H5O-, m/z 93.0343) is the principal product ion. A variety of N-acylbenzenesulfonamide derivatives were also found to overwhelmingly produce the phenoxide ion as the most intense product ion. A mechanism is proposed in which, at low energy, a carbonyl oxygen atom (C═O) is transferred to a benzene ring, known as a Smiles-type rearrangement (the amide oxygen atom attacks the arylsulfonyl group at the ipso position), in parallel and determining the reaction at high energy a nitrogen-oxygen rearrangement mechanism leads to the formation of the phenoxide ion. Tandem mass spectra of deprotonated N-benzoyl-18O-benzenesulfonamide and N-thiobenzoyl-p-toluenesulfonamide confirmed the rearrangement since base peaks at m/z 95.0384 and 123.0270 which correspond to an 18O phenoxide ion ([C6H518O]-) and a 4-methylbenzenethiolate anion ([CH3C6H4S]-) were observed, respectively. The parallel mechanism is supported by the strong correlation between the observed product ion intensities and the corresponding activation energies obtained by Density Functional Theory calculations. This is an example of a relatively simple ion with a complex path to fragmentation, being a cautionary tale for indiscriminate use of in silico spectra in place of actual measurement.
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Affiliation(s)
- Yuxue Liang
- Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Yamil Simón-Manso
- Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Pedatsur Neta
- Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Xiaoyu Yang
- Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
| | - Stephen E Stein
- Mass Spectrometry Data Center, Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
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7
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Gates PJ. Atmospheric pressure chemical ionisation mass spectrometry for the routine analysis of low molecular weight analytes. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2021; 27:13-28. [PMID: 33820464 PMCID: PMC8054169 DOI: 10.1177/14690667211005055] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
The routine analysis of low molecular weight analytes by mass spectrometry is often complicated by the lability of the analyte's functional groups and/or the lack of moieties that can be easily charged. If a molecule is too labile this precludes analysis by techniques such as electron ionisation or chemical ionisation as the analyte will undergo thermal decomposition prior to ionisation as well as spontaneous fragmentation during the ionisation process. If the analyte has a low propensity to form ions in electrospray ionisation (i.e., lacks acidic or basic sites) then often no analyte related ions are observed. In this paper, the robustness and versatility of the established method of atmospheric pressure chemical ionisation is demonstrated for the analysis of low molecular weight analytes. The utility of the technique is demonstrated through the analysis of 30 reference standards of varying functionality, and further by the analysis of 75 synthetic samples which were problematic when analysed by electron or electrospray ionisation. The resulting spectra are dominated by intact molecular species ([M+H]+ and M+ in positive ion mode and [M - H]- and [M + Cl]- in negative ion mode) along with logical neutral losses reminiscent of what you might expect from the analyte's structure (losses of H2O from alcohols or CO from aldehydes etc). This paper presents atmospheric pressure chemical ionisation as an essential tool for broadening the chemical space of successful analyses for any routine mass spectrometry service laboratory of facility.
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Affiliation(s)
- Paul J Gates
- Paul J Gates, School of Chemistry,
University of Bristol, Cantock’s Close, Bristol BS8 1TS, UK.
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8
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Neves CMB, Filipe OMS, Mota N, Santos SAO, Silvestre AJD, Santos EBH, Neves MGPMS, Simões MMQ. Photodegradation of metoprolol using a porphyrin as photosensitizer under homogeneous and heterogeneous conditions. JOURNAL OF HAZARDOUS MATERIALS 2019; 370:13-23. [PMID: 30503313 DOI: 10.1016/j.jhazmat.2018.11.055] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 10/13/2018] [Accepted: 11/15/2018] [Indexed: 06/09/2023]
Abstract
Porphyrins are known as effective photosensitizers and can be an interesting key in phototreatment of water contaminated with micropollutants such as pharmaceuticals. They already showed to be efficient photocatalysts for the degradation of dyes, chlorophenols and other pollutants. This work demonstrates the applicability of 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (H2TF5PP) as photosensitizer for treatment of water contaminated with metoprolol, a highly prescribed β-blocker, which is not completely removed in sewage treatment plants. Studies were firstly developed under homogeneous conditions with simulated solar radiation and porphyrin was found to be efficient in the photodegradation of metoprolol, following a pseudo-first order kinetics with ca. 90% metoprolol degradation after 12 h. Experiments in presence of scavengers confirmed the mechanism of degradation via singlet oxygen. Appearance of several new peaks in HPLC chromatograms indicates the formation of products, identified by HPLC-MSn. Furthermore, the porphyrin was immobilized on a silica support and used as heterogeneous photocatalyst in degradation of metoprolol. Experiments using this heterogeneous photocatalyst under real solar irradiation were also performed, and similar results were obtained. Kinetic comparison of metoprolol photodegradation in buffer solution and in real wastewater treatment plant effluent showed that the efficiency of the immobilized porphyrin was not decreased by the complex matrix of the effluent.
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Affiliation(s)
- Cláudia M B Neves
- QOPNA, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Olga M S Filipe
- CERNAS - Research Centre for Natural Resources, Environment and Society, College of Agriculture, Polytechnic Institute of Coimbra, Bencanta, 3045-601 Coimbra, Portugal
| | - Nuno Mota
- CESAM, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Sónia A O Santos
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Armando J D Silvestre
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal
| | - Eduarda B H Santos
- CESAM, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - M Graça P M S Neves
- QOPNA, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
| | - Mário M Q Simões
- QOPNA, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
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9
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Beach DG, Gabryelski W. Solution to collision induced dissociation mass spectrometry challenge. Anal Bioanal Chem 2018; 410:3927-3930. [PMID: 29926153 DOI: 10.1007/s00216-018-1044-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Daniel G Beach
- Measurement Science and Standards, National Research Council Canada, 1411 Oxford Street, Halifax, NS, B3H 3Z1, Canada.
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10
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Cao X, Cai X, Mo W. Comparing the fragmentation reactions of protonated cyclic indolyl α-amino esters in quadrupole/orbitrap and quadrupole time-of-flight mass spectrometers. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2018; 32:543-551. [PMID: 29369433 DOI: 10.1002/rcm.8063] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 01/10/2018] [Accepted: 01/10/2018] [Indexed: 06/07/2023]
Abstract
RATIONALE The comparative study of higher-energy collisional dissociation (HCD) and collision-induced dissociation (CID) mechanisms for protonated cyclic indolyl α-amino esters in quadrupole/orbitrap (Q/Orbitrap) and quadrupole time-of-flight (QTOF) mass spectrometers, respectively, is helpful to study the structures and properties of biologically active indole derivatives using tandem mass spectrometry (MS/MS) technology. METHODS HCD and CID experiments were carried out using electrospray ionization Q/Orbitrap MS and QTOFMS in positive ion mode, respectively. Only the labile hydrogens were exchanged with deuterium in hydrogen/deuterium exchange (HDX) experiments and only the aromatic indole C-H hydrogens were substituted with deuterium in regiospecific hydrogen-deuterium labeling experiments. Theoretical calculations were carried out using the density functional theory (DFT) method at the B3LYP level with the 6-311G(d,p) basis set in the Gaussian 03 package of programs. RESULTS In Q/Orbitrap MS/MS, when the added proton on the N8 position of protonated cyclic indolyl α-amino esters migrated in a stepwise fashion to the C3 position via two sequential 1,4-H shifts, an ion-neutral complex INC1 of [protonated cyclic N-sulfonyl ketimino esters/indoles] was formed by a charge-directed heterolytic cleavage of the C3 -C10 bond, while an ion-neutral complex INC3 of [cyclic N-sulfonyl ketimino esters/protonated indoles] was formed when another labile hydrogen on the N8 position successively migrated to the C4 position. Direct decomposition of INC1 and INC3 resulted in protonated cyclic N-sulfonyl ketimino esters and protonated indoles, respectively, while proton transfer led to protonated indoles and protonated cyclic N-sulfonyl ketimino esters. The HDX reaction with residual water in the HCD cell was also observed. In QTOF-MS/MS, protonated cyclic N-sulfonyl ketimino esters and protonated indoles resulted from direct decomposition of INC1 and INC3 , respectively, rather than proton transfer. CONCLUSIONS Due to the specific construction of the Q/Orbitrap and QTOF mass spectrometers, different fragmentation mechanisms medicated by ion-neutral complexes of protonated cyclic indolyl α-amino esters were proposed. This study is desirable for qualitative and quantitive investigation of indole derivatives using MS/MS technology.
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Affiliation(s)
- Xiaoji Cao
- Research Center of Analysis and Measurement, Zhejiang University of Technology, 18 Chaowang Rd, Hangzhou, Zhejiang, 310014, P.R. China
- College of Chemical Engineering, Zhejiang University of Technology, 18 Chaowang Rd, Hangzhou, Zhejiang, 310014, P.R. China
| | - Xue Cai
- College of Chemical Engineering, Zhejiang University of Technology, 18 Chaowang Rd, Hangzhou, Zhejiang, 310014, P.R. China
| | - Weimin Mo
- Research Center of Analysis and Measurement, Zhejiang University of Technology, 18 Chaowang Rd, Hangzhou, Zhejiang, 310014, P.R. China
- College of Chemical Engineering, Zhejiang University of Technology, 18 Chaowang Rd, Hangzhou, Zhejiang, 310014, P.R. China
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11
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Watkins OC, Sharpe ML, Perry NB, Krause KL. New Zealand glowworm (Arachnocampa luminosa) bioluminescence is produced by a firefly-like luciferase but an entirely new luciferin. Sci Rep 2018; 8:3278. [PMID: 29459729 PMCID: PMC5818473 DOI: 10.1038/s41598-018-21298-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 02/01/2018] [Indexed: 01/07/2023] Open
Abstract
The New Zealand glowworm, Arachnocampa luminosa, is well-known for displays of blue-green bioluminescence, but details of its bioluminescent chemistry have been elusive. The glowworm is evolutionarily distant from other bioluminescent creatures studied in detail, including the firefly. We have isolated and characterised the molecular components of the glowworm luciferase-luciferin system using chromatography, mass spectrometry and 1H NMR spectroscopy. The purified luciferase enzyme is in the same protein family as firefly luciferase (31% sequence identity). However, the luciferin substrate of this enzyme is produced from xanthurenic acid and tyrosine, and is entirely different to that of the firefly and known luciferins of other glowing creatures. A candidate luciferin structure is proposed, which needs to be confirmed by chemical synthesis and bioluminescence assays. These findings show that luciferases can evolve independently from the same family of enzymes to produce light using structurally different luciferins.
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Affiliation(s)
- Oliver C Watkins
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
- New Zealand Institute for Plant and Food Research Ltd., Department of Chemistry, University of Otago, Dunedin, New Zealand
| | - Miriam L Sharpe
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Nigel B Perry
- New Zealand Institute for Plant and Food Research Ltd., Department of Chemistry, University of Otago, Dunedin, New Zealand.
| | - Kurt L Krause
- Department of Biochemistry, University of Otago, Dunedin, New Zealand.
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Nikolić D, Macias C, Lankin DC, van Breemen RB. Collision-induced dissociation of phenethylamides: role of ion-neutral complexes. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:1385-1395. [PMID: 28558170 PMCID: PMC5555735 DOI: 10.1002/rcm.7915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/21/2017] [Accepted: 05/25/2017] [Indexed: 06/07/2023]
Abstract
RATIONALE Phenethylamides are a large group of naturally occurring molecules found both in the plant and animal kingdoms. In addition, they are used as intermediates for the synthesis of pharmaceutically important dihydro- and tetrahydroisoquinolines. To enable efficient characterization of this class of molecules, a detailed mass spectrometric fragmentation study of a broad series of analogs was carried out. METHODS The test compounds were synthesized using standard methods for amide bond formation. Low-energy high-resolution tandem mass spectra were acquired on a hybrid quadrupole/time-of-flight mass spectrometer using positive ion electrospray ionization. RESULTS A total of 26 analogs were investigated in the study. Fragmentation of phenethylamides was found to proceed via intermediate ion-neutral complexes. The complexes can break down via multiple pathways including dissociation, proton transfer, Friedel-Crafts acylation, and single electron transfer. The relative contribution of each of these pathways strongly depends on the structure of the coupling amine and acid. CONCLUSIONS A general scheme for the fragmentation of phenethylamides was developed. This study further extends the knowledge base of the ion-neutral complex by discovering Friedel-Crafts acylation as a novel reaction. The strong influence of minor structural modifications on the fragmentation patterns highlights the importance of testing many analogs in order to fully predict a fragmentation pattern of a particular class of molecules.
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Affiliation(s)
- Dejan Nikolić
- Corresponding Author: Dejan Nikolić, Department of Medicinal Chemistry and Pharmacognosy, University of Illinois at Chicago, 833 S. Wood St., Chicago, IL 60612-7231, Telephone (312) 413-5867, FAX (312) 996-7107,
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Zhao W, Zhang Q, Lu B, Sun S, Zhang S, Zhang J. Rapid Determination of Six Low Molecular Carbonyl Compounds in Tobacco Smoke by the APCI-MS/MS Coupled to Data Mining. JOURNAL OF ANALYTICAL METHODS IN CHEMISTRY 2017; 2017:8260860. [PMID: 28512594 PMCID: PMC5415865 DOI: 10.1155/2017/8260860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 01/14/2017] [Accepted: 02/15/2017] [Indexed: 06/07/2023]
Abstract
A simple method was established for the rapid determination of low molecular carbonyl compounds by the combination of atmospheric pressure chemical ionization tandem mass spectrometry (APCI-MS/MS) and data mining. The ionization was carried out in positive mode, and six low molecular carbonyl compounds of acrolein, acetone, propionaldehyde, crotonaldehyde, butanone, and butyraldehyde were analyzed by both full scan mode and daughter scan mode. To overcome the quantitative difficulties from isomer of acetone/propionaldehyde and butanone/butyraldehyde, the quantitation procedure was performed with the characteristic ion of [CH3O]+ under CID energy of 5 and 15 eV. Subsequently, the established method was successfully applied to analysis of six low molecular carbonyl compounds in tobacco smoke with analytical period less than four minutes. The contents of acrolein, acetone, propionaldehyde, crotonaldehyde, butanone, and butyraldehyde for a cigarette were about 63 ± 5.8, 325 ± 82, 55 ± 9.7, 11 ± 1.4, 67 ± 5.9, and 12 ± 1.8 μg/cig, respectively. The experimental results indicated that the established method had the potential application in rapid determination of low molecular carbonyl compounds.
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Affiliation(s)
- Wuduo Zhao
- Zhengzhou Tobacco Research Institute, China National Tobacco Corporation, Zhengzhou 450001, China
- College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, China
| | - Qidong Zhang
- Zhengzhou Tobacco Research Institute, China National Tobacco Corporation, Zhengzhou 450001, China
| | - Binbin Lu
- Zhengzhou Tobacco Research Institute, China National Tobacco Corporation, Zhengzhou 450001, China
| | - Shihao Sun
- Zhengzhou Tobacco Research Institute, China National Tobacco Corporation, Zhengzhou 450001, China
| | - Shusheng Zhang
- College of Chemistry and Molecular Engineering, Zhengzhou University, Zhengzhou 450001, China
| | - Jianxun Zhang
- Zhengzhou Tobacco Research Institute, China National Tobacco Corporation, Zhengzhou 450001, China
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Liang Y, Neta P, Simón-Manso Y, Stein SE. Reaction of arylium ions with the collision gas N2 in electrospray ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:629-636. [PMID: 26212280 DOI: 10.1002/rcm.7147] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 01/08/2015] [Accepted: 01/09/2015] [Indexed: 05/18/2023]
Abstract
RATIONALE The tandem mass spectra of many compounds contained peaks which could not have arisen from the precursor ion. Such peaks were found to be due to reaction of arylium ions with N2 in the collision cell. Therefore, this reaction was studied in detail with representative compounds. METHODS Various classes of compounds were dissolved in acetonitrile/water/formic acid and studied by electrospray ionization mass spectrometry to record their MS(2) and pseudo-MS(3) spectra in a QqQ mass spectrometer and their accurate m/z values in an Orbitrap Elite instrument. Arylium ions were found to react with N2 in the collision cell. The reaction was confirmed by pseudo-MS(3) studies, by comparison with authentic diazonium ions, and by the pressure dependence of the product ion survival yield. RESULTS Reactions of arylium ions with N2 were observed with p-toluenesulfonic acid, o-toluenesulfonamide, phenylphosphonic acid, phenol, aniline, aminonaphthalenes, benzoic acid, benzophenone, and other compounds. By using a QqQ mass spectrometer, we observed that the protonated compounds produce arylium ions, which then react with N2 to form diazonium ions. The diazonium ion was produced with N2 but not with Ar in the collision cell, and its abundance increased with increasing N2 pressure. CONCLUSIONS Arylium ions generated from a wide variety of compounds in electrospray ionization tandem mass spectrometry may react with N2 to form diazonium ions. The abundance of the diazonium ions is affected by collision energy and N2 pressure. This reaction should be considered when annotating peaks in MS/MS libraries. Published in 2015. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Yuxue Liang
- Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Pedatsur Neta
- Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Yamil Simón-Manso
- Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
| | - Stephen E Stein
- Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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Neta P, Farahani M, Simón-Manso Y, Liang Y, Yang X, Stein SE. Unexpected peaks in tandem mass spectra due to reaction of product ions with residual water in mass spectrometer collision cells. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:2645-60. [PMID: 25366411 DOI: 10.1002/rcm.7055] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 09/12/2014] [Accepted: 09/15/2014] [Indexed: 05/18/2023]
Abstract
RATIONALE Certain product ions in electrospray ionization tandem mass spectrometry are found to react with residual water in the collision cell. This reaction often leads to the formation of ions that cannot be formed directly from the precursor ions, and this complicates the mass spectra and may distort MRM (multiple reaction monitoring) results. METHODS Various drugs, pesticides, metabolites, and other compounds were dissolved in acetonitrile/water/formic acid and studied by electrospray ionization mass spectrometry to record their MS(2) and MS(n) spectra in several mass spectrometers (QqQ, QTOF, IT, and Orbitrap HCD). Certain product ions were found to react with residual water in collision cells. The reaction was confirmed by MS(n) studies and the rate of reaction was determined in the IT instrument using zero collision energy and variable activation times. RESULTS Examples of product ions reacting with water include phenyl and certain substituted phenyl cations, benzoyl-type cations formed from protonated folic acid and similar compounds by loss of the glutamate moiety, product ions formed from protonated cyclic siloxanes by loss of methane, product ions formed from organic phosphates, and certain negative ions. The reactions of product ions with residual water varied greatly in their rate constant and in the extent of reaction (due to isomerization). CONCLUSIONS Various types of product ions react with residual water in mass spectrometer collision cells. As a result, tandem mass spectra may contain unexplained peaks and MRM results may be distorted by the occurrence of such reactions. These often unavoidable reactions must be taken into account when annotating peaks in tandem mass spectra and when interpreting MRM results. Published in 2014. This article is a U.S. Government work and is in the public domain in the USA.
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Affiliation(s)
- Pedatsur Neta
- Biomolecular Measurement Division, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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