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Charest N, Lowe CN, Ramsland C, Meyer B, Samano V, Williams AJ. Improving predictions of compound amenability for liquid chromatography-mass spectrometry to enhance non-targeted analysis. Anal Bioanal Chem 2024; 416:2565-2579. [PMID: 38530399 PMCID: PMC11228616 DOI: 10.1007/s00216-024-05229-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Revised: 02/14/2024] [Accepted: 02/16/2024] [Indexed: 03/28/2024]
Abstract
Mass-spectrometry-based non-targeted analysis (NTA), in which mass spectrometric signals are assigned chemical identities based on a systematic collation of evidence, is a growing area of interest for toxicological risk assessment. Successful NTA results in better identification of potentially hazardous pollutants within the environment, facilitating the development of targeted analytical strategies to best characterize risks to human and ecological health. A supporting component of the NTA process involves assessing whether suspected chemicals are amenable to the mass spectrometric method, which is necessary in order to assign an observed signal to the chemical structure. Prior work from this group involved the development of a random forest model for predicting the amenability of 5517 unique chemical structures to liquid chromatography-mass spectrometry (LC-MS). This work improves the interpretability of the group's prior model of the same endpoint, as well as integrating 1348 more data points across negative and positive ionization modes. We enhance interpretability by feature engineering, a machine learning practice that reduces the input dimensionality while attempting to preserve performance statistics. We emphasize the importance of interpretable machine learning models within the context of building confidence in NTA identification. The novel data were curated by the labeling of compounds as amenable or unamenable by expert curators, resulting in an enhanced set of chemical compounds to expand the applicability domain of the prior model. The balanced accuracy benchmark of the newly developed model is comparable to performance previously reported (mean CV BA is 0.84 vs. 0.82 in positive mode, and 0.85 vs. 0.82 in negative mode), while on a novel external set, derived from this work's data, the Matthews correlation coefficients (MCC) for the novel models are 0.66 and 0.68 for positive and negative mode, respectively. Our group's prior published models scored MCC of 0.55 and 0.54 on the same external sets. This demonstrates appreciable improvement over the chemical space captured by the expanded dataset. This work forms part of our ongoing efforts to develop models with higher interpretability and higher performance to support NTA efforts.
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Affiliation(s)
- Nathaniel Charest
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, 27711, USA.
| | - Charles N Lowe
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, 27711, USA
| | | | - Brian Meyer
- Senior Environmental Employment Program, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, 27711, USA
| | - Vicente Samano
- Senior Environmental Employment Program, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, 27711, USA
| | - Antony J Williams
- Center for Computational Toxicology and Exposure, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, 27711, USA
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2
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Heintz C, Schnödewind L, Braubach O, Kersten H, Benter T, Wißdorf W. Observation of Large, Charged Droplet Signatures within the High-Vacuum Region of a Commercial Electrospray TOF-MS. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:508-517. [PMID: 38408762 DOI: 10.1021/jasms.3c00383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
Electrospray ionization (ESI) is one of the most prominent atmospheric pressure ionization techniques in modern mass spectrometry. It generates charged droplets from an analyte-containing solution as an initial step in the ionization process. Textbooks and the majority of the articles assume the entire droplet evaporation and release of bare analyte ions within the ionization chamber. However, non-mass-spectrometry-related literature and recent reports demonstrate droplet observation in regions of the vacuum systems of a variety of mass spectrometers. In this work, we report on the observation of large droplet fragments within the orthogonal acceleration stage of a Bruker micrOTOF by connecting an oscilloscope to an auxiliary ion current detector downstream of the acceleration stage. Moreover, we detected fragment debris even with the MCP TOF detector by evaluating individual TOF spectra. Droplet fragments appear as pronounced and intensive pulses of the ion current. This observation is clearly connected to ESI, as other atmospheric pressure ionization methods do not show this behavior. The recorded droplet signatures show clear dependencies on the ion source and transfer stage parameters. The existence of large and highly charged droplets may adversely affect or at least impact the analytical performance of the instrument due to space charge or complex heterogeneous chemical reactions. Furthermore, the penetration of large charged aggregates into the vacuum system explains the reported surface contamination after multipole stages. This contamination of critical components leads to substantially higher maintenance efforts.
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Affiliation(s)
- Chris Heintz
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Gaussstraße 20, 42119 Wuppertal, Germany
| | - Lisa Schnödewind
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Gaussstraße 20, 42119 Wuppertal, Germany
| | - Oliver Braubach
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Gaussstraße 20, 42119 Wuppertal, Germany
| | - Hendrik Kersten
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Gaussstraße 20, 42119 Wuppertal, Germany
| | - Thorsten Benter
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Gaussstraße 20, 42119 Wuppertal, Germany
| | - Walter Wißdorf
- Department of Physical and Theoretical Chemistry, University of Wuppertal, Gaussstraße 20, 42119 Wuppertal, Germany
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3
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Wang B, Tieleman DP. Release of nanodiscs from charged nano-droplets in the electrospray ionization revealed by molecular dynamics simulations. Commun Chem 2023; 6:21. [PMID: 36717705 PMCID: PMC9886951 DOI: 10.1038/s42004-023-00818-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 01/19/2023] [Indexed: 01/31/2023] Open
Abstract
Electrospray ionization (ESI) is essential for application of mass spectrometry in biological systems, as it prevents the analyte being split into fragments. However, due to lack of a clear understanding of the mechanism of ESI, the interpretation of mass spectra is often ambiguous. This is a particular challenge for complex biological systems. Here, we focus on systems that include nanodiscs as membrane environment, which are essential for membrane proteins. We performed microsecond atomistic molecular dynamics simulations to study the release of nanodiscs from highly charged nano-droplets into the gas phase, the late stage of ESI. We observed two distinct major scenarios, highlighting the diversity of morphologies of gaseous product ions. Our simulations are in reasonable agreement with experimental results. Our work provides a detailed atomistic view of the ESI process of a heterogeneous system (lipid nanodisc), which may give insights into the interpretation of mass spectra of all lipid-protein systems.
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Affiliation(s)
- Beibei Wang
- grid.20513.350000 0004 1789 9964Centre for Advanced Materials Research, Beijing Normal University, Zhuhai, 519087 People’s Republic of China
| | - D. Peter Tieleman
- grid.22072.350000 0004 1936 7697Department of Biological Sciences and Centre for Molecular Simulation, University of Calgary, Calgary, T2N 1N4 Canada
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Liu D, Cao Q, Piao Z, Li L. Confinement Dynamics of Nanodroplets between Two Surfaces: Effects of Wettability and Electric Field. Chemphyschem 2022; 23:e202200184. [PMID: 35986551 DOI: 10.1002/cphc.202200184] [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: 03/21/2022] [Revised: 08/15/2022] [Indexed: 01/04/2023]
Abstract
The electrowetting effect and related applications of tiny droplets have aroused widespread research interest. In this work, we report molecular dynamics simulations of confinement dynamics of nanodroplets under different droplet-surface interactions and surface distances under an external electric field. So far, the effect of the surface-droplet interactions on electric field-induced dynamics behaviors of droplets in confined spaces has not been extensively studied. Our results show that in the absence of electric field there is a critical value of surface wettability for the shape transition of droplets. Above this value, the droplet is divided into small droplets adhered on the bottom and top surfaces; below this value, the droplets are detached from the surfaces. When an external electric field is applied parallel to the surfaces, the droplet spreads on the surface along the direction of the electric field. It was found that the surface separation significantly influences the transition of the droplet shape. The steady morphology of the droplets under the electric field depends on the surface-droplet interaction and surface separation. We explore the underlying mechanism causing the morphological transition through analyzing the molecular interactions, the number of interracial molecules and the interaction force between the droplets and surfaces. These results provide basic insights into the molecular interactions of nanodroplets under different confined environments, and clues for applications of confined nanodroplets under the control of electric field.
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Affiliation(s)
- Dandan Liu
- College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou, 310014, P.R. China.,College of Information Science and Engineering, Jiaxing University, Jiaxing, 314001, P.R. China
| | - Qianqian Cao
- College of Information Science and Engineering, Jiaxing University, Jiaxing, 314001, P.R. China
| | - Zhongyu Piao
- College of Mechanical Engineering, Zhejiang University of Technology, Hangzhou, 310014, P.R. China
| | - Lujuan Li
- College of Information Science and Engineering, Jiaxing University, Jiaxing, 314001, P.R. China
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5
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Pan X, Cao Q, Liu D, Wu Z. Effects of Contact Behavior and Electric Field on Electrohydrodynamics of Nanodroplets. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2022. [DOI: 10.1134/s0036024422130222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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6
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Walker TE, Laganowsky A, Russell DH. Surface Activity of Amines Provides Evidence for the Combined ESI Mechanism of Charge Reduction for Protein Complexes. Anal Chem 2022; 94:10824-10831. [PMID: 35862200 PMCID: PMC9357154 DOI: 10.1021/acs.analchem.2c01814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Charge reduction reactions are important for native mass spectrometry (nMS) because lower charge states help retain native-like conformations and preserve noncovalent interactions of protein complexes. While mechanisms of charge reduction reactions are not well understood, they are generally achieved through the addition of small molecules, such as polyamines, to traditional nMS buffers. Here, we present new evidence that surface-active, charge reducing reagents carry away excess charge from the droplet after being emitted due to Coulombic repulsion, thereby reducing the overall charge of the droplet. Furthermore, these processes are directly linked to two mechanisms for electrospray ionization, specifically the charge residue and ion evaporation models (CRM and IEM). Selected protein complexes were analyzed in solutions containing ammonium acetate and selected trialkylamines or diaminoalkanes of increasing alkyl chain lengths. Results show that amines with higher surface activity have increased propensities for promoting charge reduction of the protein ions. The electrospray ionization (ESI) emitter potential was also found to be a major contributing parameter to the prevalence of charge reduction; higher emitter potentials consistently coincided with lower average charge states among all protein complexes analyzed. These results offer experimental evidence for the mechanism of charge reduction in ESI and also provide insight into the final stages of the ESI and their impact on biological ions.
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Affiliation(s)
- Thomas E Walker
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - David H Russell
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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Li Z, Fu CF, Chen Z, Tong T, Hu J, Yang J, Tian SX. Electron-Induced Synthesis of Dimethyl Ether in the Liquid-Vapor Interface of Methanol. J Phys Chem Lett 2022; 13:5220-5225. [PMID: 35670607 DOI: 10.1021/acs.jpclett.2c00787] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Ether synthesis from alcohol is known to be acid-catalyzed. Such a process could happen in the acidified liquid of alcohol, but hitherto lacking the experimental evidence. Here we demonstrate that dimethyl ether is spontaneously synthesized in the liquid-vapor interface of pure methanol after ionizing radiation with electrons. Using time-delayed tandem mass spectrometry measurements in combination with theoretical calculations, we further confirm that the protonated dimethyl ether is produced from the ion-molecule reactions not only in the dense vapor above the interface but also within the molecular clusters of the acidic interface. Our finding provides a convincing piece of evidence about the liquid-vapor interfacial acidification by the electron-impact ionizing radiation, exhibiting a promising way to control the chemical reactions in the liquid surface.
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Affiliation(s)
- Ziyuan Li
- Department of Chemical Physics, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Cen-Feng Fu
- Department of Chemical Physics, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Ziwei Chen
- Department of Chemical Physics, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Tiantian Tong
- Department of Chemical Physics, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Jie Hu
- Department of Chemical Physics, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Jinlong Yang
- Department of Chemical Physics, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
| | - Shan Xi Tian
- Department of Chemical Physics, Key Laboratory of Surface and Interface Chemistry and Energy Catalysis of Anhui Higher Education Institutes, Collaborative Innovation Center of Chemistry for Energy Materials (iChEM), Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei 230026, China
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8
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Salionov D, Ludwig C, Bjelić S. Standard-Free Quantification of Dicarboxylic Acids: Case Studies with Salt-Rich Effluents and Serum. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2022; 33:932-943. [PMID: 35511053 DOI: 10.1021/jasms.1c00377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The present study evaluates the ionization efficiency (IE) of linear and branched C2-C14 dicarboxylic acids (DCAs) by electrospray ionization (ESI) under different conditions. The influence of the concentration of organic modifier (MeOH); mobile phase additive; and its concentration, pH, and DCA structure on IE values is studied using flow injection analysis. The IE values of DCAs increase with the increase of MeOH concentration but also decrease with an increase of pH. The former is due to the increase in solvent evaporation rates; the latter is caused by an ion-pairing between the diacid and the cation (ammonium), which is confirmed by the study with different amines. The investigation of DCA ionization in the presence of different acidic mobile phase additives showed that a significant improvement in the (-)ESI responses of analytes was achieved in the presence of weak hydrophobic carboxylic acids, such as butyric or propanoic acid. Conversely, the use of strong carboxylic acids, such as trichloroacetic acid, was found to cause signal suppression. The results of the IE studies were used to develop the liquid chromatography-high-resolution mass spectrometry (LC-HRMS) method that provided instrumental limits of detection in the range from 6 to 180 pg. Furthermore, upon applying the nonparametric Gaussian process, a model for the prediction of IE values was developed, which contains the number of carbons in the molecule and MeOH concentration as model parameters. As a case study, dicarboxylic acids are quantified in salt-rich effluent and blood serum samples using the developed LC-HRMS method.
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Affiliation(s)
- Daniil Salionov
- Laboratory for Bioenergy and Catalysis, Paul Scherrer Institut PSI, 5232 Villigen, Switzerland
- Environmental Engineering Institute (IIE, GR-LUD), School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 6, CH-1015 Lausanne, Switzerland
| | - Christian Ludwig
- Laboratory for Bioenergy and Catalysis, Paul Scherrer Institut PSI, 5232 Villigen, Switzerland
- Environmental Engineering Institute (IIE, GR-LUD), School of Architecture, Civil and Environmental Engineering (ENAC), Ecole Polytechnique Fédérale de Lausanne (EPFL), Station 6, CH-1015 Lausanne, Switzerland
| | - Saša Bjelić
- Laboratory for Bioenergy and Catalysis, Paul Scherrer Institut PSI, 5232 Villigen, Switzerland
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Kwan V, Consta S. Conical Shape Fluctuations Determine the Rate of Ion Evaporation and the Emitted Cluster Size Distribution from Multicharged Droplets. J Phys Chem A 2022; 126:3229-3238. [PMID: 35549274 DOI: 10.1021/acs.jpca.2c02056] [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
The ion evaporation mechanism (IEM) is perceived to be a major pathway for disintegration of multi-ion charged droplets found in atmospheric and sprayed aerosols. However, the precise mechanism of IEM and the effect of the nature of the ions in the emitted cluster size distribution have not yet been established despite its broad use in mass spectrometry and atmospheric chemistry over the past half century. Here, we present a systematic study of the emitted ion cluster distribution in relation to their spatial distribution in the parent droplet using atomistic modeling. It is found that in the parent droplet, multiple kosmotropic and weakly polarizable chaotropic ions (Cs+) are buried deeper within the droplet than polarizable chaotropic ions (Cl-, I-). This differentiation in the ion location is only captured by a polarizable model. It is demonstrated that the emitted cluster size distribution is determined by dynamic conical deformations and not by the equilibrium ion depth within the parent droplet as the IEM models assume. Critical factors that determine the cluster size distribution such as the charge sign asymmetry that have not been considered in models and in experiments are presented. We argue that the existing IEM analytical models do not establish a clear difference between IEM and Rayleigh fission. We propose a shift in the existing view for IEM from the equilibrium properties of the parent droplet to the chemistry in the conical shape fluctuations that serve as the centers for ion emission. Consequently, chemistry in the conical fluctuations may also be a key element to explain charge states of macromolecules in mass spectrometry and may have potential applications in catalysis due to the electric field in the conical region.
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Affiliation(s)
- Victor Kwan
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Styliani Consta
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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10
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Enders JR, O’Neill GM, Whitten JL, Muddiman DC. Understanding the electrospray ionization response factors of per- and poly-fluoroalkyl substances (PFAS). Anal Bioanal Chem 2022; 414:1227-1234. [PMID: 34291300 PMCID: PMC8727445 DOI: 10.1007/s00216-021-03545-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 06/26/2021] [Accepted: 07/12/2021] [Indexed: 01/03/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are used extensively in commercial products. Their unusual solubility properties make them an ideal class of compounds for various applications. However, these same properties have led to significant contamination and bioaccumulation given their persistence in the environment. Development of analytical techniques to detect and quantify these compounds must take into account the potential for these properties to perturb these measurements, specifically the potential to bias the electrospray ionization (ESI) process. Direct injection ESI analysis of 23 different PFAS species revealed that hydrophobicity and PFAS class can predict the ESI overall response factors. In this study, a method for predicting the behavior of individual PFAS compounds, including relative retention order in chromatography, is presented which is simply based on the number of fluorine atoms in the molecule as well as the class of the compound (e.g., perfluroalkylcarboxylic acids) vs. computational estimations (e.g., non-polar surface area and logP).
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Affiliation(s)
- Jeffrey R. Enders
- Molecular Education Technology and Research Innovate Center (METRIC), North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA,Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695, USA
| | - Grace M. O’Neill
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - Jerry L. Whitten
- Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA
| | - David C. Muddiman
- Molecular Education Technology and Research Innovate Center (METRIC), North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA,Department of Chemistry, North Carolina State University, 2620 Yarbrough Drive, Raleigh, NC 27695, USA,Corresponding Author, , David C. Muddiman, Jacob and Betty Belin Distinguished Professor, Department of Chemistry, Molecular Education, Technology and Research Innovation Center (METRIC), North Carolina State University, 2620 Yarbrough Drive, Raleigh, North Carolina 27695, USA
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12
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Calixte EI, Liyanage OT, Gass DT, Gallagher ES. Formation of Carbohydrate-Metal Adducts from Solvent Mixtures during Electrospray: A Molecular Dynamics and ESI-MS Study. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2021; 32:2738-2745. [PMID: 34735139 DOI: 10.1021/jasms.1c00179] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Electrospray ionization (ESI) is frequently used to produce gas-phase ions for mass spectrometry (MS)-based techniques. The composition of solvents used in ESI-MS is often manipulated to enhance analyte ionization, including for carbohydrates. Moreover, to characterize analyte structures, ESI has been coupled to hydrogen/deuterium exchange, ion mobility, and tandem MS. Therefore, it is important to understand how solvent composition affects the structure of carbohydrates during and after ESI. In this work, we use molecular dynamics to simulate the desolvation of ESI droplets containing a model carbohydrate and observe the formation of carbohydrate adducts with metal ions. Molecular-level details on the effects of formulating mixtures of water, methanol, and acetonitrile to achieve enhanced ionization are presented. We complement our simulations with ESI-MS experiments. We report that when sprayed from aqueous mixtures containing volatile solvents, carbohydrates ionize to form metal-ion adducts rapidly due to rapid solvent evaporation rather than changes in the ionization mechanism. We find that when sprayed from solvent mixtures, carbohydrates are primarily solvated by water due to the migration of more volatile solvents to the surface of the droplet. Ultimately, the structure of the carbohydrate varies depending on its solvent environment, as inter- and intramolecular interactions are affected. We propose that solvents with 25% or more water may be used to enhance the ionization of carbohydrates with minimal effect on the structure during and after ESI.
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Affiliation(s)
- Emvia I Calixte
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798-7348, United States
| | - O Tara Liyanage
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798-7348, United States
| | - Darren T Gass
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798-7348, United States
| | - Elyssia S Gallagher
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, Texas 76798-7348, United States
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Dryahina K, Polášek M, Smith D, Španěl P. Sensitivity of secondary electrospray ionization mass spectrometry to a range of volatile organic compounds: Ligand switching ion chemistry and the influence of Zspray™ guiding electric fields. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2021; 35:e9187. [PMID: 34473872 DOI: 10.1002/rcm.9187] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/27/2021] [Accepted: 08/27/2021] [Indexed: 06/13/2023]
Abstract
RATIONALE Secondary electrospray ionization (SESI) is currently only semi-quantitative. In the Zspray™ arrangement of SESI-MS, the transfer of ions from near atmospheric pressure to a triple quadrupole is achieved by guiding electric fields that partially desolvate both reagent and analyte ions which must be understood. Also, to make SESI-MS more quantitative, the mechanisms and the kinetics of the reaction processes, especially ligand switching reactions of hydrated hydronium reagent ions, H3 O+ (H2 O)n , with volatile organic compound (VOC) molecules, need to be understood. METHODS A modified Zspray™ ESI ion source operating at sub-atmospheric pressure with analyte sample gas introduced via an inlet coaxial with the spray was used. Variation of the ion-guiding electric fields was used to reveal the degree of desolvation of both reagent and analyte ions. The instrument sensitivity was determined for several classes of VOCs by introducing bag samples of suitably varying concentrations as quantified on-line using selected ion flow tube MS. RESULTS Electric field desolvation resulted in largely protonated VOCs, MH+ , and their monohydrates, MH+ H2 O, and for some VOCs proton-bound dimer ions, MH+ M, were formed. There was a highly linear response of the ion signal to the measured VOC sample concentration, which provided the instrument sensitivities, S, for 25 VOCs. The startling results show very wide variations in S from near 0 to 1 for hydrocarbons, and up to 100, on a relative scale, for polar compounds such as monoketones and unsaturated aldehydes. CONCLUSIONS The complex ion chemistry occurring in the SESI ion source, largely involving gas-phase ligand switching, results in widely variable sensitivities for different classes of VOCs. The sensitivity is observed to depend on the dipole moment and proton affinity of the analyte VOC molecule, M, and to decrease with the observed fraction of MH+ H2 O, but other yet unrecognized factors must play a significant role.
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Affiliation(s)
- Kseniya Dryahina
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Miroslav Polášek
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
| | - David Smith
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
| | - Patrik Španěl
- J. Heyrovsky Institute of Physical Chemistry of the Czech Academy of Sciences, Prague, Czechia
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15
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Ahmed Khaireh M, Liger-Belair G, Bonhommeau DA. Toward In Silico Prediction of CO 2 Diffusion in Champagne Wines. ACS OMEGA 2021; 6:11231-11239. [PMID: 34056278 PMCID: PMC8153942 DOI: 10.1021/acsomega.0c06275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/25/2020] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
Carbon dioxide diffusion is the main physical process behind the formation and growth of bubbles in sparkling wines, especially champagne wines. By approximating brut-labeled champagnes as carbonated hydroalcoholic solutions, molecular dynamics (MD) simulations are carried out with six rigid water models and three CO2 models to evaluate CO2 diffusion coefficients. MD simulations are little sensitive to the CO2 model but proper water modeling is essential to reproduce experimental measurements. A satisfactory agreement with nuclear magnetic resonance (NMR) data is only reached at all temperatures for simulations based on the OPC and TIP4P/2005 water models; the similar efficiency of these two models is attributed to their common properties such as low mixture enthalpy, same number of hydrogen bonds, alike water tetrahedrality, and multipole values. Correcting CO2 diffusion coefficients to take into account their system-size dependence does not significantly alter the quality of the results. Estimates of viscosities deduced from the Stokes-Einstein formula are found in excellent agreement with viscometry on brut-labeled champagnes, while theoretical densities tend to underestimate experimental values. OPC and TIP4P/2005 water models appear to be choice water models to investigate CO2 solvation and transport properties in carbonated hydroalcoholic mixtures and should be the best candidates for any MD simulations concerning wines, spirits, or multicomponent mixtures with alike chemical composition.
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Kwan V, O’Dwyer R, Laur D, Tan J, Consta S. Relation between Ejection Mechanism and Ion Abundance in the Electric Double Layer of Droplets. J Phys Chem A 2021; 125:2954-2966. [DOI: 10.1021/acs.jpca.1c01522] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Victor Kwan
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Ryan O’Dwyer
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - David Laur
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
| | - Jiahua Tan
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
- College of Chemistry, Nankai University, Tianjin 300071, P. R. China
| | - Styliani Consta
- Department of Chemistry, The University of Western Ontario, London, Ontario N6A 5B7, Canada
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17
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Chen Z, Fu CF, Li Z, Hu J, Li H, Yang J, Tian SX. Identifying the Molecular Orientation and Clusters in the Liquid-Vapor Interface of 1-Propanol by Time-Delayed Mass Spectrometry. J Phys Chem Lett 2020; 11:7510-7516. [PMID: 32813525 DOI: 10.1021/acs.jpclett.0c02097] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Structural inhomogeneity of the liquid-vapor interface, such as the spatial orientation of molecular specific groups and the non-uniform distribution of hydrogen-bonded (HB) clusters, is crucial for understanding the physicochemical processes therein. Although the molecular orientation at the outermost layer was authenticated, to date, direct experimental evidence of the in situ existence of different-sized HB clusters, as a long-standing theoretical argument, is still lacking. Here we report time-delayed electron-impact tandem mass spectrometry, and its powerful ability to identify the local structures of the liquid-vapor interface of 1-propanol is demonstrated not only by mapping the molecular orientations both in the outermost layer and in the subsurface but also by validating the existence of the HB molecular dimers in the subsurface by detecting their protonated ions. We further distinguish two different sources of the protonated dimer: the gas-phase protonation of the neutral dimer that evaporates in advance and the time-lag evaporation of the protonated dimer produced in the subsurface. This methodology is a brand-new way to explore the microstructures and the electron-driven chemical reactions in different local regions of the liquid-vapor interface.
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18
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Apsokardu MJ, Krasnomowitz JM, Jiang S, Johnston MV. Ion Formation from Rapidly Heated Aqueous Droplets by Droplet-Assisted Ionization. J Phys Chem A 2020; 124:7313-7321. [PMID: 32833452 DOI: 10.1021/acs.jpca.0c07101] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
When aqueous droplets travel through a temperature-controlled capillary from atmospheric pressure into a vacuum, they undergo aerodynamic and/or thermal breakup to give charged progeny droplets that subsequently produce gas-phase molecular ions from solutes that were in the original droplets. This phenomenon is the basis of droplet-assisted ionization, a method that was recently developed for online characterization of aerosols by mass spectrometry. The conditions allowing initial droplets to break up into progeny droplets were studied by computational fluid dynamics (CFD) with a droplet evaporation model. The CFD results were then used to interpret experimental measurements of ion current vs capillary wall temperature. For capillary wall temperatures below about 150 °C, the abilities of droplets to undergo either aerodynamic or thermal breakup are strongly temperature dependent. Above this temperature, the mode of initial droplet breakup becomes temperature independent, and the temperature dependence of the ion signal intensity can be explained in relation to ion formation from charged progeny droplets. Activation energies for ion formation fall into two main categories: ∼41 kJ mol-1 for droplets containing predominantly nonionic solutes, which matches the enthalpy of vaporization for water and suggests a charge residue process for ion formation, and ∼24 kJ mol-1 for droplets containing salts, which suggests an ion evaporation process where the ion is ejected from the droplet surface within a cluster of solvent molecules.
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Affiliation(s)
- Michael J Apsokardu
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Justin M Krasnomowitz
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Shuai Jiang
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Murray V Johnston
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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19
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Song F, Niu H, Fan J, Chen Q, Wang G, Liu L. Molecular dynamics study on the coalescence and break-up behaviors of ionic droplets under DC electric field. J Mol Liq 2020. [DOI: 10.1016/j.molliq.2020.113195] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Villatoro J, Zühlke M, Riebe D, Beitz T, Weber M, Löhmannsröben HG. Sub-ambient pressure IR-MALDI ion mobility spectrometer for the determination of low and high field mobilities. Anal Bioanal Chem 2020; 412:5247-5260. [PMID: 32488389 DOI: 10.1007/s00216-020-02735-0] [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: 03/10/2020] [Revised: 05/16/2020] [Accepted: 05/20/2020] [Indexed: 11/25/2022]
Abstract
A new ion mobility (IM) spectrometer, enabling mobility measurements in the pressure range between 5 and 500 mbar and in the reduced field strength range E/N of 5-90 Td, was developed and characterized. Reduced mobility (K0) values were studied under low E/N (constant value) as well as high E/N (deviation from low field K0) for a series of molecular ions in nitrogen. Infrared matrix-assisted laser desorption ionization (IR-MALDI) was used in two configurations: a source working at atmospheric pressure (AP) and, for the first time, an IR-MALDI source working with a liquid (aqueous) matrix at sub-ambient/reduced pressure (RP). The influence of RP on IR-MALDI was examined and new insights into the dispersion process were gained. This enabled the optimization of the IM spectrometer for best analytical performance. While ion desolvation is less efficient at RP, the transport of ions is more efficient, leading to intensity enhancement and an increased number of oligomer ions. When deciding between AP and RP IR-MALDI, a trade-off between intensity and resolving power has to be considered. Here, the low field mobility of peptide ions was first measured and compared with reference values from ESI-IM spectrometry (at AP) as well as collision cross sections obtained from molecular dynamics simulations. The second application was the determination of the reduced mobility of various substituted ammonium ions as a function of E/N in nitrogen. The mobility is constant up to a threshold at high E/N. Beyond this threshold, mobility increases were observed. This behavior can be explained by the loss of hydrated water molecules.
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Affiliation(s)
- José Villatoro
- Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany. .,Konrad-Zuse-Zentrum für Informationstechnik Berlin, Takustraße 7, 14195, Berlin-Dahlem, Germany.
| | - Martin Zühlke
- Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Daniel Riebe
- Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Toralf Beitz
- Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
| | - Marcus Weber
- Konrad-Zuse-Zentrum für Informationstechnik Berlin, Takustraße 7, 14195, Berlin-Dahlem, Germany
| | - Hans-Gerd Löhmannsröben
- Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476, Potsdam, Germany
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21
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Filippov AV, Chen X, Harris C, Stace AJ, Besley E. Interaction between particles with inhomogeneous surface charge distributions: Revisiting the Coulomb fission of dication molecular clusters. J Chem Phys 2019; 151:154113. [PMID: 31640356 DOI: 10.1063/1.5119347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
An analytical solution describing the electrostatic interaction between particles with inhomogeneous surface charge distributions has been developed. For particles, each carrying a single charge, the solution equates to the presence of a point charge residing on the surface, which makes it particularly suitable for investigating the Coulomb fission of doubly charged clusters close to the Rayleigh instability limit. For a series of six separate molecular dication clusters, center-of-mass kinetic energy releases have been extracted from experimental measurements of their kinetic energy spectra following Coulomb fission. These data have been compared with Coulomb energy barriers calculated from the electrostatic interaction energies given by this new solution. For systems with high dielectric permittivity, results from the point charge model provide a viable alternative to kinetic energy releases calculated on the assumption of a uniform distribution of surface charge. The equivalent physical picture for the clusters would be that of a trapped proton. For interacting particles with low dielectric permittivity, a uniform distribution of charge provides better agreement with the experimental results.
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Affiliation(s)
- A V Filippov
- Troitsk Institute for Innovation and Fusion Research, Troitsk, Moscow 108840, Russia
| | - X Chen
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - C Harris
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - A J Stace
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
| | - E Besley
- School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom
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22
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Liyanage OT, Brantley MR, Calixte EI, Solouki T, Shuford KL, Gallagher ES. Characterization of Electrospray Ionization (ESI) Parameters on In-ESI Hydrogen/Deuterium Exchange of Carbohydrate-Metal Ion Adducts. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:235-247. [PMID: 30353291 DOI: 10.1007/s13361-018-2080-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 10/04/2018] [Indexed: 05/25/2023]
Abstract
The conformations of glycans are crucial for their biological functions. In-electrospray ionization (ESI) hydrogen/deuterium exchange-mass spectrometry (HDX-MS) is a promising technique for studying carbohydrate conformations since rapidly exchanging functional groups, e.g., hydroxyls, can be labeled on the timeframe of ESI. However, regular application of in-ESI HDX to characterize carbohydrates requires further analysis of the in-ESI HDX methodology. For instance, in this method, HDX occurs concurrently to the analyte transitioning from solution to gas-phase ions. Therefore, there is a possibility of sampling both gas-phase and solution-phase conformations of the analyte. Herein, we differentiate in-ESI HDX of metal-adducted carbohydrates from gas-phase HDX and illustrate that this method analyzes solvated species. We also systematically examine the effects of ESI parameters, including spray solvent composition, auxiliary gas flow rate, sheath gas flow rate, sample infusion rate, sample concentration, and spray voltage, and discuss their effects on in-ESI HDX. Further, we model the structural changes of a trisaccharide, melezitose, and its intramolecular and intermolecular hydrogen bonding in solvents with different compositions of methanol and water. These molecular dynamic simulations support our experimental results and illustrate how an individual ESI parameter can alter the conformations we sample by in-ESI HDX. In total, this work illustrates how the fundamental processes of ESI alter the magnitude of HDX for carbohydrates and suggest parameters that should be considered and/or optimized prior to performing experiments with this in-ESI HDX technique. Graphical Abstract ᅟ.
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Affiliation(s)
- O Tara Liyanage
- Department of Chemistry & Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - Matthew R Brantley
- Department of Chemistry & Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - Emvia I Calixte
- Department of Chemistry & Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - Touradj Solouki
- Department of Chemistry & Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - Kevin L Shuford
- Department of Chemistry & Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA
| | - Elyssia S Gallagher
- Department of Chemistry & Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798, USA.
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23
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Kelley MP, Yang P, Clark SB, Clark AE. Competitive Interactions Within Cm(III) Solvation in Binary Water/Methanol Solutions. Inorg Chem 2018; 57:10050-10058. [PMID: 30067015 DOI: 10.1021/acs.inorgchem.8b01214] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Competitive forces exist in multicomponent solutions, and within electrolytes they consist of both ion-solvent and solvent-solvent interactions. These can influence a myriad of processes, including ligand complexation. In the case of water/alcohol solutions, recent work revealed an interesting dilemma regarding the overall solution dynamics and organization as compared to solute-solvent interactions. This is particularly true for highly charged ions in solution, whose ion-solvent interactions were demonstrated to be highly sensitive to the composition of the immediate solvation environment. Faster solvent exchange should be observed about the ion, considering that second-order Møller-Plesset perturbation theory predicts an average decrease in ion-solvent dissociation energy when methanol enters the first solvation shell of Cm3+(aq). Yet the addition of methanol to water causes the dynamic features of the hydrogen-bond network of the entire solution to slow. The apparent competition between these contrary forces was examined using a combination of electronic structure calculations with both ab initio and classical molecular dynamics simulations, using binary water/methanol solutions and Cm3+ as a representative solute. This combination of theoretical methods predicts that, among the competitive effects of the solvent-solvent and ion-solvent interactions, the solution-phase dynamics imparted by the addition of methanol to water kinetically restricts the solvation exchange rates about Cm3+ in these binary solutions.
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Affiliation(s)
- Morgan P Kelley
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico , United States
| | - Ping Yang
- Theoretical Division , Los Alamos National Laboratory , Los Alamos , New Mexico , United States
| | - Sue B Clark
- Pacific Northwest National Laboratory , Richland , Washington , United States
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24
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Yarger TJ, Yuill EM, Baker LA. Probe-Substrate Distance Control in Desorption Electrospray Ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:558-565. [PMID: 29181813 DOI: 10.1007/s13361-017-1844-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 11/03/2017] [Accepted: 11/03/2017] [Indexed: 06/07/2023]
Abstract
We introduce probe-substrate distance (Dps)-control to desorption electrospray ionization (DESI) and report a systematic investigation of key experimental parameters. Examination of voltage, flow rate, and nebulizing gas pressure suggests as Dps decreases, the distance-dependent spray current increases, until a critical point. At the critical point the relationship inverts, and the spray current decreases as the probe moves closer to the surface due to constriction of solution flow by the nebulizing gas. Dps control was used to explore the use of spray current as a signal for feedback positioning, while mass spectrometry imaging was performed simultaneously. Further development of this technique is expected to find application in study of structure-function relationships for clinical diagnostics, biological investigation, and materials characterization. Graphical abstract ᅟ.
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Affiliation(s)
- Tyler J Yarger
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Elizabeth M Yuill
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Lane A Baker
- Department of Chemistry, Indiana University, 800 E. Kirkwood Ave., Bloomington, IN, 47405, USA.
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25
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Affiliation(s)
- Mari Ojakivi
- Institute of Chemistry; University of Tartu; Ravila 14a Tartu 50411 Estonia
| | - Jaanus Liigand
- Institute of Chemistry; University of Tartu; Ravila 14a Tartu 50411 Estonia
| | - Anneli Kruve
- Institute of Chemistry and Biochemistry; Free University of Berlin; Takustr. 3 14195 Berlin Germany
- Institute of Chemistry; University of Tartu; Ravila 14a Tartu 50411 Estonia
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26
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Guérard F, de Bont L, Gakière B, Tcherkez G. Evaluation and application of a targeted SPE-LC-MS method for quantifying plant hormones and phenolics in Arabidopsis. FUNCTIONAL PLANT BIOLOGY : FPB 2017; 44:624-634. [PMID: 32480593 DOI: 10.1071/fp16300] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 03/03/2017] [Indexed: 06/11/2023]
Abstract
Application of metabolomics techniques to plant physiology is now considerable, and LC-MS is often being used for non-targeted, semi-quantitative analysis of effects caused by mutations or environmental conditions. However, examination of signalling metabolites like hormones require absolute rather than semi-quantitative quantitation, since their effect in planta is strongly dependent upon concentration. Further, plant hormones belong to different chemical classes and thus simultaneous quantitation remains highly challenging. Here we present an LC-MS method that allows the simultaneous absolute quantitation of six hormone families as well as selected phenolics. The technique requires solid phase extraction with a sulfonated cation exchange phase before analysis, and use calibration curves instead of isotopically labelled standards, which are indeed not commercially available for many hormonal molecules. The use of the total signal (including adducts) rather than a single quantifying mass appears to be crucial to avoid quantification errors because the ion distribution between adducts is found to be concentration-dependent. The different hormones considered appear to have contrasted ionisation efficiency due to their physical properties. However, the relatively low variability and the satisfactory response to standard additions show that the technique is accurate and reproducible. It is applied to Arabidopsis plants subjected to water stress, using either the wild-type or lines with altered NAD biosynthesis causing changes in salicylate signalling and phenylpropanoid levels. As expected, analyses show an increase in abscisic acid upon water stress and a consistent modification of phenolic compounds (including salicylate) in mutants.
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Affiliation(s)
- Florence Guérard
- Plateforme Métabolisme-Métabolome, Institute of Plant Sciences Paris-Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France
| | - Linda de Bont
- Plateforme Métabolisme-Métabolome, Institute of Plant Sciences Paris-Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France
| | - Bertrand Gakière
- Plateforme Métabolisme-Métabolome, Institute of Plant Sciences Paris-Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université d'Evry, Université Paris-Diderot, Université Paris-Saclay, Bâtiment 630, 91405 Orsay, France
| | - Guillaume Tcherkez
- Research School of Biology, College of Medicine, Biology and Environment, Australian National University, Canberra, ACT 2601, Australia
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27
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Keifer DZ, Alexander AW, Jarrold MF. Spontaneous Mass and Charge Losses from Single Multi-Megadalton Ions Studied by Charge Detection Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:498-506. [PMID: 28083758 DOI: 10.1007/s13361-016-1582-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Revised: 12/14/2016] [Accepted: 12/16/2016] [Indexed: 06/06/2023]
Abstract
Spontaneous mass and charge losses from individual multi-megadalton ions have been observed with charge detection mass spectrometry (CDMS) by trapping single hepatitis B virus (HBV) capsids for 3 s. Gradual increases in the oscillation frequency of single ions in the ion trap are attributed mainly to mass loss (probably solvent, water, and/or salt). The total mass lost during the 3 s trapping period peaks at around 20 kDa for 4 MDa HBV T = 4 capsids. Discrete frequency drops punctuate the gradual increases in the oscillation frequencies. The drops are attributed to a sudden loss of charge. In most cases a single positive charge is lost along with some mass (on average around 1000 Da). Charge loss occurs for over 40% of the trapped ions. It usually occurs near the beginning of the trapping event, and it occurs preferentially in regions of the trap with strong electric fields, indicating that external electric fields promote charge loss. This process may contribute to the decrease in m/z resolution that often occurs with megadalton ions. Graphical Abstract ᅟ.
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Affiliation(s)
- David Z Keifer
- Chemistry Department, Indiana University, 800 E Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Andrew W Alexander
- Chemistry Department, Indiana University, 800 E Kirkwood Ave., Bloomington, IN, 47405, USA
| | - Martin F Jarrold
- Chemistry Department, Indiana University, 800 E Kirkwood Ave., Bloomington, IN, 47405, USA.
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28
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Koszinowski K, Lissy F. ESI activity of Br⁻, BF₄⁻ , ClO₄⁻ and BPh₄⁻ anions in the presence of Li⁺ and NBu⁴⁺ counter-ions. JOURNAL OF MASS SPECTROMETRY : JMS 2017; 52:144-151. [PMID: 28098404 DOI: 10.1002/jms.3911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 01/12/2017] [Accepted: 01/14/2017] [Indexed: 06/06/2023]
Abstract
To improve our understanding of the electrospray ionization (ESI) process, we have subjected equimolar mixtures of salts A+ X- (A+ = Li+ , NBu4+ ; X- = Br- , ClO4- , BF4- , BPh4- ) in different solvents (CH3 CN, tetrahydrofuran, CH3 OH, H2 O) to negative-ion mode ESI and analyzed the relative ESI activity of the different anionic model analytes. The ESI activity of the large and hydrophobic BPh4- ion greatly exceeds that of the smaller and more hydrophilic anions Br- , ClO4- and BF4- , which we ascribe to its higher surface activity. Moreover, the ESI activity of the anions is modulated by the action of the counter-ions and their different tendency toward ion pairing. The tendency toward ion pairing can be reduced by the addition of the chelating ligands 12-crown-4 and 2.2.1 cryptand and is, although to a smaller degree, further influenced by the variation of the solvent. Complementary electrical conductivity measurements afford additional information on the interactions of the ionic constituents of the sample solutions. Copyright © 2017 John Wiley & Sons, Ltd.
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Affiliation(s)
- K Koszinowski
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
| | - F Lissy
- Institut für Organische und Biomolekulare Chemie, Georg-August-Universität Göttingen, Tammannstr. 2, 37077, Göttingen, Germany
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29
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Liigand J, Laaniste A, Kruve A. pH Effects on Electrospray Ionization Efficiency. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:461-469. [PMID: 27966175 DOI: 10.1007/s13361-016-1563-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 11/18/2016] [Accepted: 11/20/2016] [Indexed: 05/28/2023]
Abstract
Electrospray ionization efficiency is known to be affected by mobile phase composition. In this paper, a detailed study of analyte ionization efficiency dependence on mobile phase pH is presented. The pH effect was studied on 28 compounds with different chemical properties. Neither pK a nor solution phase ionization degree by itself was observed to be sufficient at describing how aqueous phase pH affects the ionization efficiency of the analyte. Therefore, the analyte behavior was related to various physicochemical properties via linear discriminant analyses. Distinction between pH-dependent and pH-independent compounds was achieved using two parameters: number of potential charge centers and hydrogen bonding acceptor capacity (in the case of 80% acetonitrile) or polarity of neutral form of analyte and pK a (in the case of 20% acetonitrile). It was also observed that decreasing pH may increase ionization efficiency of a compound by more than two orders of magnitude. Graphical Abstract ᅟ.
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Affiliation(s)
- Jaanus Liigand
- Institute of Chemistry, Faculty of Science and Technology, University of Tartu, Ravila 14A, 50411, Tartu, Estonia.
| | - Asko Laaniste
- Institute of Chemistry, Faculty of Science and Technology, University of Tartu, Ravila 14A, 50411, Tartu, Estonia
| | - Anneli Kruve
- Institute of Chemistry, Faculty of Science and Technology, University of Tartu, Ravila 14A, 50411, Tartu, Estonia
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30
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Gao F, Zhang L, Li X, Jiao F, Zhang W, Zhang Q. A Refined Model for Ionization of Small Molecules in Electrospray Mass Spectrometry. CHEM LETT 2016. [DOI: 10.1246/cl.160391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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31
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Kruve A. Influence of mobile phase, source parameters and source type on electrospray ionization efficiency in negative ion mode. JOURNAL OF MASS SPECTROMETRY : JMS 2016; 51:596-601. [PMID: 28239972 DOI: 10.1002/jms.3790] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Revised: 05/18/2016] [Accepted: 05/19/2016] [Indexed: 06/06/2023]
Abstract
Electrospray ionization (ESI) efficiency is known to be affected by the properties of the analytes, source design and source parameters. In this study, the ionization efficiency of 17 acidic compounds at various conditions in ESI negative ion mode was evaluated. Namely, the influence of organic solvent content in the mobile phase, ionization source parameters, ionization source geometry and functionality (conventional ESI, ESI with thermal focussing and with additional internal nebulizer gas) was studied. It was observed that the ionization efficiency in thermal focussing ESI is only marginally affected by the organic solvent composition, while for conventional ESI and ESI with internal nebulizer gas, the ionization efficiency increases significantly with increasing organic modifier content. For all ionization sources and mobile phase compositions, the ionization efficiency values between different setups showed good correlation. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Anneli Kruve
- Institute of Chemistry, University of Tartu, Ravila 14a, Tartu, 50411, Estonia
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32
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Zheng F, Wang D, Fang H, Wang H, Wang M, Huang K, Chen H, Feng S. Controlled Crystallization of Sodium Chloride Nanocrystals in Microdroplets Produced by Electrospray from an Ultra-Dilute Solution. Eur J Inorg Chem 2016. [DOI: 10.1002/ejic.201501453] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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33
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Bongiorno D, Ceraulo L, Indelicato S, Turco Liveri V, Indelicato S. Charged supramolecular assemblies of surfactant molecules in gas phase. MASS SPECTROMETRY REVIEWS 2016; 35:170-187. [PMID: 26113001 DOI: 10.1002/mas.21476] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Indexed: 06/04/2023]
Abstract
The aim of this review is to critically analyze recent literature on charged supramolecular assemblies formed by surfactant molecules in gas phase. Apart our specific interest on this research area, the stimuli to undertake the task arise from the widespread theoretical and applicative benefits emerging from a comprehensive view of this topic. In fact, the study of the formation, stability, and physicochemical peculiarities of non-covalent assemblies of surfactant molecules in gas phase allows to unveil interesting aspects such as the role of attractive, repulsive, and steric intermolecular interactions as driving force of supramolecular organization in absence of interactions with surrounding medium and the size and charge state dependence of aggregate structural and dynamical properties. Other interesting aspects worth to be investigated are joined to the ability of these assemblies to incorporate selected solubilizates molecules as well as to give rise to chemical reactions within a single organized structure. In particular, the incorporation of large molecules such as proteins has been of recent interest with the objective to protect their structure and functionality during the transition from solution to gas phase. Exciting fall-out of the study of gas phase surfactant aggregates includes mass and energy transport in the atmosphere, origin of life and simulation of supramolecular aggregation in the interstellar space. Moreover, supramolecular assemblies of amphiphilic molecules in gas phase could find remarkable applications as atmospheric cleaning agents, nanosolvents and nanoreactors for specialized chemical processes in confined space. Mass spectrometry techniques have proven to be particularly suitable to generate these assemblies and to furnish useful information on their size, size polydispersity, stability, and structural organization. On the other hand molecular dynamics simulations have been very useful to rationalize many experimental findings and to furnish a vivid picture of the structural and dynamic features of these aggregates. Thus, in this review, we will focus on the most important achievements gained in recent years by both these investigative tools.
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Affiliation(s)
- David Bongiorno
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche Farmaceutiche (STEBICEF), Università degli Studi di Palermo, Via Archirafi 32, I-90123, Palermo, Italy
- Centro Grandi Apparecchiature-UniNetLab, Università degli Studi di Palermo, Via Marini 14, I-90128, Palermo, Italy
| | - Leopoldo Ceraulo
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche Farmaceutiche (STEBICEF), Università degli Studi di Palermo, Via Archirafi 32, I-90123, Palermo, Italy
- Centro Grandi Apparecchiature-UniNetLab, Università degli Studi di Palermo, Via Marini 14, I-90128, Palermo, Italy
| | - Sergio Indelicato
- Core Laboratory of Quality control and Chemical Risk, Policlinico P. Giaccone, Università di Palermo, via del Vespro 129, I-90127, Palermo, Italy
| | - Vincenzo Turco Liveri
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche Farmaceutiche (STEBICEF), Università degli Studi di Palermo, Via Archirafi 32, I-90123, Palermo, Italy
| | - Serena Indelicato
- Dipartimento di Scienze e Tecnologie Biologiche Chimiche Farmaceutiche (STEBICEF), Università degli Studi di Palermo, Via Archirafi 32, I-90123, Palermo, Italy
- Centro Grandi Apparecchiature-UniNetLab, Università degli Studi di Palermo, Via Marini 14, I-90128, Palermo, Italy
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Zobnina VG, Chagovets VV, Boryak OA, Kosevich MV. A mass spectrometric study and computer modeling of noncovalent interactions of cytosine with polyethylene glycol oligomers. JOURNAL OF ANALYTICAL CHEMISTRY 2015. [DOI: 10.1134/s1061934815130110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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Higashi H, Tokumi T, Hogan CJ, Suda H, Seto T, Otani Y. Simultaneous ion and neutral evaporation in aqueous nanodrops: experiment, theory, and molecular dynamics simulations. Phys Chem Chem Phys 2015; 17:15746-55. [DOI: 10.1039/c5cp01730k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Neutral and ion evaporation from aqueous nanodrops is examined experimentally, numerically, and theoretically, demonstrating the validity of analytical models.
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Affiliation(s)
- Hidenori Higashi
- Faculty of Natural Systems
- Institute of Science and Engineering
- Kanazawa University
- Kanazawa
- Japan
| | - Takuya Tokumi
- Faculty of Natural Systems
- Institute of Science and Engineering
- Kanazawa University
- Kanazawa
- Japan
| | | | - Hiroshi Suda
- Home Appliances Development Center
- Corporate Engineering Division
- Appliances Company
- Panasonic Corporation
- Kusatsu
| | - Takafumi Seto
- Faculty of Natural Systems
- Institute of Science and Engineering
- Kanazawa University
- Kanazawa
- Japan
| | - Yoshio Otani
- Faculty of Natural Systems
- Institute of Science and Engineering
- Kanazawa University
- Kanazawa
- Japan
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36
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Mortensen DN, Williams ER. Investigating protein folding and unfolding in electrospray nanodrops upon rapid mixing using theta-glass emitters. Anal Chem 2014; 87:1281-7. [PMID: 25525976 PMCID: PMC4303338 DOI: 10.1021/ac503981c] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
![]()
Theta-glass emitters are used to
rapidly mix two solutions to induce
either protein folding or unfolding during nanoelectrospray (nanoESI).
Mixing acid-denatured myoglobin with an aqueous ammonium acetate solution
to increase solution pH results in protein folding during nanoESI.
A reaction time and upper limit to the droplet lifetime of 9 ±
2 μs is obtained from the relative abundance of the folded conformer
in these rapid mixing experiments compared to that obtained from solutions
at equilibrium and a folding time constant of 7 μs. Heme reincorporation
does not occur, consistent with the short droplet lifetime and the
much longer time constant for this process. Similar mixing experiments
with acid-denatured cytochrome c and the resulting
folding during nanoESI indicate a reaction time of between 7 and 25
μs depending on the solution composition. The extent of unfolding
of holo-myoglobin upon rapid mixing with theta-glass emitters is less
than that reported previously (Fisher
et al. Anal. Chem.2014, 86, 4581−458824702054), a result
that is attributed to the much smaller, ∼1.5 μm, average
o.d. tips used here. These results indicate that the time frame during
which protein folding or unfolding can occur during nanoESI depends
both on the initial droplet size, which can be varied by changing
the emitter tip diameter, and on the solution composition. This study
demonstrates that protein folding or unfolding processes that occur
on the ∼10 μs time scale can be readily investigated
using rapid mixing with theta-glass emitters combined with mass spectrometry.
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Affiliation(s)
- Daniel N Mortensen
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States
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37
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Bonhommeau DA, Perret A, Nuzillard JM, Cilindre C, Cours T, Alijah A, Liger-Belair G. Unveiling the Interplay Between Diffusing CO2 and Ethanol Molecules in Champagne Wines by Classical Molecular Dynamics and (13)C NMR Spectroscopy. J Phys Chem Lett 2014; 5:4232-4237. [PMID: 26273967 DOI: 10.1021/jz502025e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The diffusion coefficients of carbon dioxide (CO2) and ethanol (EtOH) in carbonated hydroalcoholic solutions and Champagne wines are evaluated as a function of temperature by classical molecular dynamics (MD) simulations and (13)C NMR spectroscopy measurements. The excellent agreement between theoretical and experimental diffusion coefficients suggest that ethanol is the main molecule, apart from water, responsible for the value of the CO2 diffusion coefficients in typical Champagne wines, a result that could likely be extended to most sparkling wines with alike ethanol concentrations. CO2 and EtOH hydrodynamical radii deduced from viscometry measurements by applying the Stokes-Einstein relationship are found to be mostly constant and in close agreement with MD predictions. The reliability of our approach should be of interest to physical chemists aiming to model transport phenomena in supersaturated aqueous solutions or water/alcohol mixtures.
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Affiliation(s)
- David A Bonhommeau
- †GSMA, UMR CNRS 7331, Université de Reims Champagne-Ardenne, Campus Moulin de la Housse BP 1039, 51687 Reims Cedex 2, France
| | - Alexandre Perret
- †GSMA, UMR CNRS 7331, Université de Reims Champagne-Ardenne, Campus Moulin de la Housse BP 1039, 51687 Reims Cedex 2, France
| | - Jean-Marc Nuzillard
- ‡ICMR, UMR CNRS 7312, Université de Reims Champagne-Ardenne, Campus Moulin de la Housse BP 1039, 51687 Reims Cedex 2, France
| | - Clara Cilindre
- †GSMA, UMR CNRS 7331, Université de Reims Champagne-Ardenne, Campus Moulin de la Housse BP 1039, 51687 Reims Cedex 2, France
| | - Thibaud Cours
- †GSMA, UMR CNRS 7331, Université de Reims Champagne-Ardenne, Campus Moulin de la Housse BP 1039, 51687 Reims Cedex 2, France
| | - Alexander Alijah
- †GSMA, UMR CNRS 7331, Université de Reims Champagne-Ardenne, Campus Moulin de la Housse BP 1039, 51687 Reims Cedex 2, France
| | - Gérard Liger-Belair
- †GSMA, UMR CNRS 7331, Université de Reims Champagne-Ardenne, Campus Moulin de la Housse BP 1039, 51687 Reims Cedex 2, France
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38
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Liigand J, Kruve A, Leito I, Girod M, Antoine R. Effect of mobile phase on electrospray ionization efficiency. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1853-1861. [PMID: 25142325 DOI: 10.1007/s13361-014-0969-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 07/16/2014] [Accepted: 07/17/2014] [Indexed: 06/03/2023]
Abstract
Electrospray (ESI) ionization efficiencies (IE) of a set of 10 compounds differing by chemical nature, extent of ionization in solution (basicity), and by hydrophobicity (tetrapropylammonium and tetraethylammonium ion, triethylamine, 1-naphthylamine, N,N-dimethylaniline, diphenylphthalate, dimethylphtahalate, piperidine, pyrrolidine, pyridine) have been measured in seven mobile phases (three acetonitrile percentages 20%, 50%, and 80%, and three different pH-adjusting additives, 0.1% formic acid, 1 mM ammonia, pH 5.0 buffer combination) using the relative measurement method. MS parameters were optimized separately for each ion. The resulting relative IE data were converted into comparable logIE values by anchoring them to the logIE of tetrapropylammonium ion taking into account the differences of ionization in different solvents and thereby making the logIE values of the compounds comparable across solvents. The following conclusions were made from analysis of the data. The compounds with pK(a) values in the range of the solution pH values displayed higher IE at lower pH. The sensitivity of IE towards pH depends on hydrophobicity being very strong with pyridine, weaker with N,N-dimethylaniline, and weakest with 1-naphthylamine. IEs of tetraalkylammonium ions and triethylamine were expectedly insensitive towards solution pH. Surprisingly high IEs of phthalate esters were observed. The differences in solutions with different acetonitrile content and similar pH were smaller compared with the pH effects. These results highlight the importance of hydrophobicity in electrospray and demonstrate that high hydrophobicity can sometimes successfully compensate for low basicity.
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Affiliation(s)
- Jaanus Liigand
- Institute of Chemistry, Faculty of Science and Technology, University of Tartu, Ravila 14A, 50411, Tartu, Estonia,
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39
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Jirsák J, Moučka F, Nezbeda I. Insight into Electrospinning via Molecular Simulations. Ind Eng Chem Res 2014. [DOI: 10.1021/ie404268f] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Jan Jirsák
- Faculty
of Science, J. E. Purkinje University in Ústí nad Labem, C̆eské mládez̆e 8, 400 96 Ústí nad Labem, Czech Republic
- Institute
of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Rozvojová 1, 165 02 Praha 6, Czech Republic
| | - Filip Moučka
- Faculty
of Science, J. E. Purkinje University in Ústí nad Labem, C̆eské mládez̆e 8, 400 96 Ústí nad Labem, Czech Republic
| | - Ivo Nezbeda
- Faculty
of Science, J. E. Purkinje University in Ústí nad Labem, C̆eské mládez̆e 8, 400 96 Ústí nad Labem, Czech Republic
- Institute
of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, Rozvojová 1, 165 02 Praha 6, Czech Republic
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40
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Rouse SL, Marcoux J, Robinson CV, Sansom MSP. Dodecyl maltoside protects membrane proteins in vacuo. Biophys J 2014; 105:648-56. [PMID: 23931313 DOI: 10.1016/j.bpj.2013.06.025] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 05/14/2013] [Accepted: 06/17/2013] [Indexed: 11/26/2022] Open
Abstract
Molecular dynamics simulations have been used to characterize the effects of transfer from aqueous solution to a vacuum to inform our understanding of mass spectrometry of membrane-protein-detergent complexes. We compared two membrane protein architectures (an α-helical bundle versus a β-barrel) and two different detergent types (phosphocholines versus an alkyl sugar) with respect to protein stability and detergent packing. The β-barrel membrane protein remained stable as a protein-detergent complex in vacuum. Zwitterionic detergents formed conformationally destabilizing interactions with an α-helical membrane protein after detergent micelle inversion driven by dehydration in vacuum. In contrast, a nonionic alkyl sugar detergent resisted micelle inversion, maintaining the solution-phase conformation of the protein. This helps to explain the relative stability of membrane proteins in the presence of alkyl sugar detergents such as dodecyl maltoside.
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Affiliation(s)
- Sarah L Rouse
- Department of Biochemistry, University of Oxford, United Kingdom
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41
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Hawkridge AM. Practical Considerations and Current Limitations in Quantitative Mass Spectrometry-based Proteomics. QUANTITATIVE PROTEOMICS 2014. [DOI: 10.1039/9781782626985-00001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Quantitative mass spectrometry (MS)-based proteomics continues to evolve through advances in sample preparation, chemical and biochemical reagents, instrumentation, and software. The breadth of proteomes and biological applications combined with unique experimental goals makes optimizing MS-based proteomics workflows a daunting task. Several MS-based instrument platforms are commercially available with LC-MS/MS being the most common for quantitative proteomics studies. Although the direction of LC-MS/MS instrumentation development is toward more user-friendly interfaces, there remain fundamental aspects of the technology that can be optimized for improving data quality. The intent of this chapter is to provide an introductory framework for understanding some of the more significant LC-MS/MS experimental conditions that can influence quantitative MS-based proteomics measurements, including electrospray ionization (ESI) bias and ion transmission efficiency. Because each commercial LC-MS/MS system is unique with regard to ESI source, transmission optics, ion isolation and trapping, ion fragmentation, and mass analysis, the use of design of experiments (DoE) is discussed as a potential approach for efficiently optimizing multiple inter-related factors.
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Affiliation(s)
- Adam M. Hawkridge
- Departments of Pharmaceutics & Pharmacotherapy and Outcomes Sciences, Virginia Commonwealth University School of Pharmacy Richmond VA 23298 USA
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42
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Perret A, Bonhommeau DA, Liger-Belair G, Cours T, Alijah A. CO2 diffusion in champagne wines: a molecular dynamics study. J Phys Chem B 2014; 118:1839-47. [PMID: 24506162 DOI: 10.1021/jp410998f] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Although diffusion is considered as the main physical process responsible for the nucleation and growth of carbon dioxide bubbles in sparkling beverages, the role of each type of molecule in the diffusion process remains unclear. In the present study, we have used the TIP5P and SPC/E water models to perform force field molecular dynamics simulations of CO2 molecules in water and in a water/ethanol mixture respecting Champagne wine proportions. CO2 diffusion coefficients were computed by applying the generalized Fick's law for the determination of multicomponent diffusion coefficients, a law that simplifies to the standard Fick's law in the case of champagnes. The CO2 diffusion coefficients obtained in pure water and water/ethanol mixtures composed of TIP5P water molecules were always found to exceed the coefficients obtained in mixtures composed of SPC/E water molecules, a trend that was attributed to a larger propensity of SPC/E water molecules to form hydrogen bonds. Despite the fact that the SPC/E model is more accurate than the TIP5P model to compute water self-diffusion and CO2 diffusion in pure water, the diffusion coefficients of CO2 molecules in the water/ethanol mixture are in much better agreement with the experimental values of 1.4 - 1.5 × 10(-9) m(2)/s obtained for Champagne wines when the TIP5P model is employed. This difference was deemed to rely on the larger propensity of SPC/E water molecules to maintain the hydrogen-bonded network between water molecules and form new hydrogen bonds with ethanol, although statistical issues cannot be completely excluded. The remarkable agreement between the theoretical CO2 diffusion coefficients obtained within the TIP5P water/ethanol mixture and the experimental data specific to Champagne wines makes us infer that the diffusion coefficient in these emblematic hydroalcoholic sparkling beverages is expected to remain roughly constant whathever their proportions in sugars, glycerol, or peptides.
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Affiliation(s)
- Alexandre Perret
- GSMA, CNRS UMR 7331, Université de Reims Champagne-Ardenne , Campus Moulin de la Housse BP 1039, 51687 Reims Cedex 2, France
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43
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Silveira JA, Fort KL, Kim D, Servage KA, Pierson NA, Clemmer DE, Russell DH. From Solution to the Gas Phase: Stepwise Dehydration and Kinetic Trapping of Substance P Reveals the Origin of Peptide Conformations. J Am Chem Soc 2013; 135:19147-53. [DOI: 10.1021/ja4114193] [Citation(s) in RCA: 125] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Joshua A. Silveira
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Kyle L. Fort
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - DoYong Kim
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Kelly A. Servage
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Nicholas A. Pierson
- Department
of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - David E. Clemmer
- Department
of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
| | - David H. Russell
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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44
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Chen X, Bichoutskaia E, Stace AJ. Coulomb Fission in Dielectric Dication Clusters: Experiment and Theory on Steps That May Underpin the Electrospray Mechanism. J Phys Chem A 2013; 117:3877-86. [DOI: 10.1021/jp311950p] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Affiliation(s)
- Xiaojing Chen
- Department of Physical
and Theoretical Chemistry, School
of Chemistry, University of Nottingham,
University Park, Nottingham NG7 2RD, United Kingom
| | - Elena Bichoutskaia
- Department of Physical
and Theoretical Chemistry, School
of Chemistry, University of Nottingham,
University Park, Nottingham NG7 2RD, United Kingom
| | - Anthony J. Stace
- Department of Physical
and Theoretical Chemistry, School
of Chemistry, University of Nottingham,
University Park, Nottingham NG7 2RD, United Kingom
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45
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Longhi G, Ceselli A, Fornili SL, Abbate S, Ceraulo L, Liveri VT. Molecular dynamics of electrosprayed water nanodroplets containing sodium bis(2-ethylhexyl)sulfosuccinate. JOURNAL OF MASS SPECTROMETRY : JMS 2013; 48:478-486. [PMID: 23584941 DOI: 10.1002/jms.3179] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 11/22/2012] [Accepted: 02/01/2013] [Indexed: 06/02/2023]
Abstract
The behavior of aqueous solutions of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) subject to electrospray ionization (ESI) has been investigated by molecular dynamics (MD) simulations at three temperatures (350, 500 and 800 K). We consider several types of water nanodroplets containing AOTNa molecules and composed of a fixed number of water molecules (1000), N(AOT)(0) AOT(-) anions (N(AOT)(0) = 0, 5, 10) and N(Na)(0) sodium ions (N(Na)(0) = 0, 5, 10, 15, 20): in a short time scale (less than 1 ns), the AOTNa molecules, initially forming direct micelles in the interior of the water nanodroplets, are observed in all cases to diffuse nearby the nanodroplet surface, so that the hydrophilic heads and sodium ions become surrounded by water molecules, whereas the alkyl chains lay at the droplet surface. Meanwhile, evaporation of water molecules and of solvated sodium ions occurs, leading to a decrease of the droplet size and charge. At 350 K, no ejection of neutral or charged surfactant molecules is observed, whereas at 500 K, some fragmentation occurs, and at 800 K, this event becomes more frequent. The interplay of all these processes, which depend on the values of temperature, N(AOT)(0) and N(Na)(0) eventually leads to anhydrous charged surfactant aggregates with prevalence of monocharged ones, in agreement with experimental results of ESI mass spectrometry. The quantitative analysis of the MD trajectories allows to evidence molecular details potentially useful in designing future ESI experimental conditions.
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Affiliation(s)
- Giovanna Longhi
- Dipartimento di Scienze Biomediche e Biotecnologie, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy
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46
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Bonvin G, Schappler J, Rudaz S. Capillary electrophoresis–electrospray ionization-mass spectrometry interfaces: Fundamental concepts and technical developments. J Chromatogr A 2012; 1267:17-31. [DOI: 10.1016/j.chroma.2012.07.019] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 07/04/2012] [Accepted: 07/06/2012] [Indexed: 01/24/2023]
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47
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Meyer T, Gabelica V, Grubmüller H, Orozco M. Proteins in the gas phase. WILEY INTERDISCIPLINARY REVIEWS-COMPUTATIONAL MOLECULAR SCIENCE 2012. [DOI: 10.1002/wcms.1130] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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48
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Konermann L, Ahadi E, Rodriguez AD, Vahidi S. Unraveling the Mechanism of Electrospray Ionization. Anal Chem 2012; 85:2-9. [DOI: 10.1021/ac302789c] [Citation(s) in RCA: 359] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Lars Konermann
- Department
of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7 Canada
| | - Elias Ahadi
- Department
of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7 Canada
| | - Antony D. Rodriguez
- Department
of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7 Canada
| | - Siavash Vahidi
- Department
of Chemistry, The University of Western Ontario, London, Ontario, N6A 5B7 Canada
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49
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Daub CD, Cann NM. Molecular Dynamics Simulations to Examine Structure, Energetics, and Evaporation/Condensation Dynamics in Small Charged Clusters of Water or Methanol Containing a Single Monatomic Ion. J Phys Chem A 2012; 116:10488-95. [DOI: 10.1021/jp308217q] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Christopher D. Daub
- Department of Chemistry, Queen’s University, 90 Bader
Lane, Kingston,
Ontario, Canada K7L3N6
| | - Natalie M. Cann
- Department of Chemistry, Queen’s University, 90 Bader
Lane, Kingston,
Ontario, Canada K7L3N6
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50
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Schröder D. Applications of electrospray ionization mass spectrometry in mechanistic studies and catalysis research. Acc Chem Res 2012; 45:1521-32. [PMID: 22702223 DOI: 10.1021/ar3000426] [Citation(s) in RCA: 150] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mechanistic studies form the basis for a better understanding of chemical processes, helping researchers develop more sustainable reactions by increasing the yields of the desired products, reducing waste production, and lowering the consumption of resources and energy overall. Conventional methods for the investigation of reaction mechanisms in solution include kinetic studies, isotope labeling, trapping of reactive intermediates, and advanced spectroscopic techniques. Within the past decade, electrospray ionization mass spectrometry (ESI-MS) has provided an additional tool for mechanistic studies because researchers can directly probe liquid samples by mass spectrometry under gentle conditions. Specifically, ESI-MS allows researchers to identify the molecular entities present in solution over the course of a chemical transformation. ESI-MS is particularly useful for investigations of organic reactions or metal catalysis that involve ionic intermediates. Accordingly, researchers are increasingly using ESI-MS in mechanistic studies and catalyst development. However, a further understanding of the ESI process and how it can facilitate mechanistic studies has not accompanied this increased use of the technique. Therefore, at least in part the ESI-MS method not only has offered great promise for the elucidation of reaction mechanisms but also became a black box with the occasional risk of misinterpretation. In this Account, we summarize applications of ESI-MS for synthetic and mechanistic research. Recently researchers have established direct linkages between gas-phase data obtained via ESI-MS and processes occurring in solution, and these results reveal qualitative and quantitative correlations between ESI-MS measurements and solution properties. In this context, time dependences, concentration series, and counterion effects can serve as criteria that allow researchers assess if the gas-phase measurements correlate with the situation in the solution. Furthermore, we report developments that bridge the gap between gas-phase and solution-phase studies. We also describe predictions derived from ESI-MS that have been verified with solution-phase chemistry experiments.
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Affiliation(s)
- Detlef Schröder
- Institute of Organic Chemistry and Biochemistry, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
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