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Díaz-Sánchez LM, Blanco-Tirado C, Combariza MY. Electron-transfer MALDI MS methodology for microalgae/phytoplankton pigments analysis. MethodsX 2023; 10:102140. [PMID: 37007620 PMCID: PMC10050785 DOI: 10.1016/j.mex.2023.102140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Accepted: 03/15/2023] [Indexed: 04/04/2023] Open
Abstract
The method describes pigment analysis from microalgae/phytoplankton extracts using electron-transfer Matrix-Assisted Laser Desorption Ionization Mass Spectrometry (ET MALDI MS). Current microalgae/phytoplankton pigment analysis requires resource- and time-intensive chromatographic methods due to the broad polarity range of the target analytes. On the other hand, traditional MALDI MS chlorophyll analysis, using proton-transfer matrices such as 2,5-dihydroxybenzoic acid (DHB) or α-cyano-4-hydroxycinnamic acid (CHCA), results in central metal loss and phytol-ester cleavage. ET MALDI MS is an alternative for the rapid screening and detection of pigments in microalgae extracts.•MALDI matrices with ionization energies above 8.0 eV guarantee electron-transfer processes from photosynthetic and photoprotective pigments whose ionization energies lay below 7.5 eV.•ET MALDI MS pigment analysis agrees with data gathered from conventional chromatographic techniques (HPLC) and optical microscopy for pigment extracts from C. vulgaris cultures and freshwater phytoplankton samples.•The ET MALDI MS method allows fast and reliable detection of pigments in microalgae cultures and freshwater phytoplankton samples.
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Robinson KN, Steven RT, Race AM, Bunch J. The Influence of MS Imaging Parameters on UV-MALDI Desorption and Ion Yield. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2019; 30:1284-1293. [PMID: 30949969 DOI: 10.1007/s13361-019-02193-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 02/12/2019] [Accepted: 03/11/2019] [Indexed: 06/09/2023]
Abstract
Ultraviolet matrix-assisted laser desorption/ionization mass spectrometry imaging (UV-MALDI MSI) is a widely used technique for imaging molecular distributions within biological systems. While much work exists concerning desorption in UV-MALDI MS, the effects of commonly varied parameters for imaging applications (repetition rate, use of continuous raster mode and raster speed), which determine spatial resolution and limits of detection for the technique, remain largely unknown. We use multiple surface characterization modalities to obtain quantitative measurements of material desorption and analyte ion yield in thin film model systems of two matrix compounds, arising from different UV-MALDI MSI sampling conditions. Observed changes in resulting ablation feature point to matrix-dependent spatial resolution and laser-induced matrix modification effects. Analyte ion yields of 10-9 to 10-6 are observed. Complex changes in ion yield, between spot and raster sampling and arising from varied laser repetition rate and raster speed, are observed. Graphical Abstract.
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Affiliation(s)
- Kenneth N Robinson
- National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI), National Physical Laboratory, Teddington, UK
- Advanced Materials and Healthcare Technologies Division (AMHT), University of Nottingham, Nottingham, UK
| | - Rory T Steven
- National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI), National Physical Laboratory, Teddington, UK.
| | - Alan M Race
- National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI), National Physical Laboratory, Teddington, UK
| | - Josephine Bunch
- National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI), National Physical Laboratory, Teddington, UK.
- Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London, UK.
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014. MASS SPECTROMETRY REVIEWS 2018; 37:353-491. [PMID: 29687922 DOI: 10.1002/mas.21530] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 11/29/2016] [Indexed: 06/08/2023]
Abstract
This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.
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Affiliation(s)
- David J Harvey
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7FZ, United Kingdom
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4
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Liang SP, Lu IC, Tsai ST, Chen JL, Lee YT, Ni CK. Laser Pulse Width Dependence and Ionization Mechanism of Matrix-Assisted Laser Desorption/Ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2017; 28:2235-2245. [PMID: 28707193 DOI: 10.1007/s13361-017-1734-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 01/24/2017] [Accepted: 06/05/2017] [Indexed: 06/07/2023]
Abstract
Ultraviolet laser pulses at 355 nm with variable pulse widths in the region from 170 ps to 1.5 ns were used to investigate the ionization mechanism of matrix-assisted laser desorption/ionization (MALDI) for matrices 2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid (CHCA), and sinapinic acid (SA). The mass spectra of desorbed ions and the intensity and velocity distribution of desorbed neutrals were measured simultaneously for each laser shot. These quantities were found to be independent of the laser pulse width. A comparison of the experimental measurements and numerical simulations according to the multiphoton ionization, coupled photophysical and chemical dynamics (CPCD), and thermally induced proton transfer models showed that the predictions of thermally induced proton transfer model were in agreement with the experimental data, but those of the multiphoton ionization model were not. Moreover, the predictions of the CPCD model based on singlet-singlet energy pooling were inconsistent with the experimental data of CHCA and SA, but were consistent with the experimental data of DHB only when some parameters used in the model were adjusted to extreme values. Graphical Abstract ᅟ.
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Affiliation(s)
- Sheng-Ping Liang
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
| | - I-Chung Lu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
- Department of Chemistry, Wayne State University, Detroit, MI, 48202, USA
| | - Shang-Ting Tsai
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
| | - Jien-Lian Chen
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
| | - Yuan Tseh Lee
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan
| | - Chi-Kung Ni
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan.
- Department of Chemistry, National Tsing Hua University, Hsinchu, 30013, Taiwan.
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Niehaus M, Schnapp A, Koch A, Soltwisch J, Dreisewerd K. New Insights into the Wavelength Dependence of MALDI Mass Spectrometry. Anal Chem 2017. [PMID: 28636332 DOI: 10.1021/acs.analchem.7b01744] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The interplay between the wavelength of the laser and the absorption profile of the matrix constitutes a crucial factor in matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS). Numerous studies have shown that typically best analytical results are obtained if the laser wavelength matches the UV absorption band of the matrix in the solid state well. However, many powerful matrices exhibit peak absorptions which differ notably from the standard MALDI laser wavelengths of 337, 349, and 355 nm, respectively. Here we used two wavelength-tunable lasers to investigate the MALDI wavelength dependence with a selected set of such matrices. We studied 3-hydroxypicolinic acid (3-HPA), 2,4,6-trihydroxyacetophenon (THAP), dithranol (1,8-dihydroxy-10H-anthracen-9-on), 2-(4'-hydroxybenzeneazo)benzoic acid (HABA), and 6-aza-2-thiothymine (ATT). For analyte systems we investigated DNA oligomers (3-HPA), phospholipids (dithranol, THAP, HABA), and non-covalent peptide-peptide and protein-peptide complexes (ATT). We recorded analyte ion and total ion counts as a function of wavelength and laser fluence between 213 and 600 nm. Although the so-generated comprehensive heat maps generally corroborated the previously made findings, several fine features became notable. For example, despite a still high optical absorption exhibited by some of the matrices in the visible wavelength range, ion yields generally dropped strongly, indicating a change in ionization mechanism. Moreover, the non-covalent complexes were optimally detected at wavelengths corresponding to a relatively low optical absorptivity of the ATT matrix, presumably because of ejection of a particular cold MALDI plume. Our comprehensive data shed useful light into the MALDI mechanisms and could assist in further methodological advancement of the technique.
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Affiliation(s)
- Marcel Niehaus
- Institute for Hygiene, Biomedical Mass Spectrometry, University of Münster , D-48149 Münster, Germany
| | - Andreas Schnapp
- Institute for Hygiene, Biomedical Mass Spectrometry, University of Münster , D-48149 Münster, Germany
| | - Annika Koch
- Institute for Hygiene, Biomedical Mass Spectrometry, University of Münster , D-48149 Münster, Germany
| | - Jens Soltwisch
- Institute for Hygiene, Biomedical Mass Spectrometry, University of Münster , D-48149 Münster, Germany.,Interdisciplinary Center for Clinical Research (IZKF), University of Münster , D-48149 Münster, Germany
| | - Klaus Dreisewerd
- Institute for Hygiene, Biomedical Mass Spectrometry, University of Münster , D-48149 Münster, Germany.,Interdisciplinary Center for Clinical Research (IZKF), University of Münster , D-48149 Münster, Germany
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Lou X, van Dongen JLJ, Milroy LG, Meijer EW. Generation of gas-phase ions from charged clusters: an important ionization step causing suppression of matrix and analyte ions in matrix-assisted laser desorption/ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:2628-2634. [PMID: 27643391 DOI: 10.1002/rcm.7741] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2016] [Revised: 09/02/2016] [Accepted: 09/14/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Ionization in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is a very complicated process. It has been reported that quaternary ammonium salts show extremely strong matrix and analyte suppression effects which cannot satisfactorily be explained by charge transfer reactions. Further investigation of the reasons causing these effects can be useful to improve our understanding of the MALDI process. METHODS The dried-droplet and modified thin-layer methods were used as sample preparation methods. In the dried-droplet method, analytes were co-crystallized with matrix, whereas in the modified thin-layer method analytes were deposited on the surface of matrix crystals. Model compounds, tetrabutylammonium iodide ([N(Bu)4 ]I), cesium iodide (CsI), trihexylamine (THA) and polyethylene glycol 600 (PEG 600), were selected as the test analytes given their ability to generate exclusively pre-formed ions, protonated ions and metal ion adducts respectively in MALDI. RESULTS The strong matrix suppression effect (MSE) observed using the dried-droplet method might disappear using the modified thin-layer method, which suggests that the incorporation of analytes in matrix crystals contributes to the MSE. By depositing analytes on the matrix surface instead of incorporating in the matrix crystals, the competition for evaporation/ionization from charged matrix/analyte clusters could be weakened resulting in reduced MSE. Further supporting evidence for this inference was found by studying the analyte suppression effect using the same two sample deposition methods. CONCLUSIONS By comparing differences between the mass spectra obtained via the two sample preparation methods, we present evidence suggesting that the generation of gas-phase ions from charged matrix/analyte clusters may induce significant suppression of matrix and analyte ions. The results suggest that the generation of gas-phase ions from charged matrix/analyte clusters is an important ionization step in MALDI-MS. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Xianwen Lou
- Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600, MB, Eindhoven, The Netherlands
| | - Joost L J van Dongen
- Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600, MB, Eindhoven, The Netherlands
| | - Lech-Gustav Milroy
- Laboratory of Chemical Biology, Department of Biomedical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600, MB, Eindhoven, The Netherlands
- Institute of Complex Molecular Systems (ICMS), Eindhoven University of Technology, P.O. Box 513, 5600, MB, Eindhoven, The Netherlands
| | - E W Meijer
- Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600, MB, Eindhoven, The Netherlands
- Institute of Complex Molecular Systems (ICMS), Eindhoven University of Technology, P.O. Box 513, 5600, MB, Eindhoven, The Netherlands
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7
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Knochenmuss R. The Coupled Chemical and Physical Dynamics Model of MALDI. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2016; 9:365-385. [PMID: 27070182 DOI: 10.1146/annurev-anchem-071015-041750] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The coupled physical and chemical dynamics model of ultraviolet matrix-assisted laser desorption/ionization (MALDI) has reproduced and explained a wide variety of MALDI phenomena. The rationale behind and elements of the model are reviewed, including the photophysics, kinetics, and thermodynamics of primary and secondary reaction steps. Experimental results are compared with model predictions to illustrate the foundations of the model, coupling of ablation and ionization, differences between and commonalities of matrices, secondary charge transfer reactions, ionization in both polarities, fluence and concentration dependencies, and suppression and enhancement effects.
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Affiliation(s)
- Richard Knochenmuss
- Departement für Chemie und Biochemie, Universität Bern, CH-3012 Bern, Switzerland;
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Independent assessment of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) sample preparation quality: A novel statistical approach for quality scoring. Anal Chim Acta 2016; 919:1-10. [PMID: 27086093 DOI: 10.1016/j.aca.2016.03.031] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 03/17/2016] [Accepted: 03/19/2016] [Indexed: 12/25/2022]
Abstract
Preparation of samples according to an optimized method is crucial for accurate determination of polymer sample characteristics by Matrix-Assisted Laser Desorption Ionization (MALDI) analysis. Sample preparation conditions such as matrix choice, cationization agent, deposition technique or even the deposition volume should be chosen to suit the sample of interest. Many sample preparation protocols have been developed and employed, yet finding the optimal sample preparation protocol remains a challenge. Because an objective comparison between the results of diverse protocols is not possible, "gut-feeling" or "good enough" is often decisive in the search for an optimum. This implies that sub-optimal protocols are used, leading to a loss of mass spectral information quality. To address this problem a novel analytical strategy based on MALDI imaging and statistical data processing was developed in which eight parameters were formulated to objectively quantify the quality of sample deposition and optimal MALDI matrix composition and finally sum up to an overall quality score of the sample deposition. These parameters can be established in a fully automated way using commercially available mass spectrometry imaging instruments without any hardware adjustments. With the newly developed analytical strategy the highest quality MALDI spots were selected, resulting in more reproducible and more valuable spectra for PEG in a variety of matrices. Moreover, our method enables an objective comparison of sample preparation protocols for any analyte and opens up new fields of investigation by presenting MALDI performance data in a clear and concise way.
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9
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Kirmess KM, Knochenmuss R, Blanchard GJ, Kinsel GR. MALDI ionization mechanisms investigated by comparison of isomers of dihydroxybenzoic acid. JOURNAL OF MASS SPECTROMETRY : JMS 2016; 51:79-85. [PMID: 26757075 DOI: 10.1002/jms.3725] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2015] [Revised: 10/23/2015] [Accepted: 10/24/2015] [Indexed: 06/05/2023]
Abstract
Matrix-assisted laser desorption/ionization (MALDI) ion formation mechanisms were investigated by comparison of isomers of dihydroxybenzoic acid (DHB). These exhibit substantially different MALDI performance, the basis for which was not previously understood. Luminescence decay curves are used here to estimate excited electronic state properties relevant for the coupled chemical and physical dynamics (CPCD) model. With these estimates, the CPCD predictions for relative total ion and analyte ion yields are in good agreement with the data for the DHB isomers. Predictions of a thermal equilibrium model were also compared and found to be incompatible with the data. Copyright © 2015 John Wiley & Sons, Ltd.
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Affiliation(s)
- Kristopher M Kirmess
- Department of Chemistry and Biochemistry, Southern Illinois University Carbondale, Carbondale, IL, 62901, USA
| | | | - Gary J Blanchard
- Department of Chemistry, Michigan State University, East Lansing, MI, 48824, USA
| | - Gary R Kinsel
- Department of Chemistry and Biochemistry, Southern Illinois University Carbondale, Carbondale, IL, 62901, USA
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Nagoshi K, Inatomi K, Osaka I, Takayama M. Photochemical Reactions of Aminonaphthols Caused by Laser Desorption/Ionization. Mass Spectrom (Tokyo) 2016; 5:A0048. [DOI: 10.5702/massspectrometry.a0048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 06/30/2016] [Indexed: 11/23/2022] Open
Affiliation(s)
- Keishiro Nagoshi
- Mass Spectrometry Laboratory, Graduate School of Nanobioscience, Yokohama City University
| | - Kazuma Inatomi
- Mass Spectrometry Laboratory, Graduate School of Nanobioscience, Yokohama City University
| | - Issey Osaka
- Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology
| | - Mitsuo Takayama
- Mass Spectrometry Laboratory, Graduate School of Nanobioscience, Yokohama City University
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Knochenmuss R. Ion Yields in the Coupled Chemical and Physical Dynamics Model of Matrix-Assisted Laser Desorption/Ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015; 26:1645-1648. [PMID: 26265040 DOI: 10.1007/s13361-015-1225-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Revised: 06/20/2015] [Accepted: 06/21/2015] [Indexed: 06/04/2023]
Abstract
The Coupled Chemical and Physical Dynamics (CPCD) model of matrix assisted laser desorption ionization has been restricted to relative rather than absolute yield comparisons because the rate constant for one step in the model was not accurately known. Recent measurements are used to constrain this constant, leading to good agreement with experimental yield versus fluence data for 2,5-dihydroxybenzoic acid. Parameters for alpha-cyano-4-hydroxycinnamic acid are also estimated, including contributions from a possible triplet state. The results are compared with the polar fluid model, the CPCD is found to give better agreement with the data.
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12
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Knochenmuss R. Energetics and kinetics of thermal ionization models of MALDI. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1521-1527. [PMID: 24912435 DOI: 10.1007/s13361-014-0931-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 04/10/2014] [Accepted: 05/12/2014] [Indexed: 06/03/2023]
Abstract
Thermal models of ultraviolet MALDI ionization based on the polar fluid concept are re-examined. Key components are very high solvating power of the fluidized matrix and consequent low reaction-free energy, attainment of thermal equilibrium in the fluid, and negligible recombination losses. None of these are found to hold in a MALDI event. The reaction-free energy in the hot matrix must be near the gas phase value, ion formation is too slow to approach equilibrium, and geminate recombination of autoprotolysis pairs greatly increases the initial loss rate. The maximum thermal ion yield is estimated to be many orders of magnitude below experimental values.
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13
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Knochenmuss R. MALDI mechanisms: wavelength and matrix dependence of the coupled photophysical and chemical dynamics model. Analyst 2014; 139:147-56. [DOI: 10.1039/c3an01446k] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Traldi P, Molin L, Crotti S, Seraglia R, Czarnocki Z, Szawkało J, Maurin JK, Pluciński FA. Chemical aspects of the primary ionization mechanisms in matrix-assisted laser desorption ionization. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2014; 20:437-444. [PMID: 25905868 DOI: 10.1255/ejms.1296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
It has been proposed that the primary ionization mechanism occurring in matrix-assisted laser desorption ionization (MALDI) experiments originates from the presence, in the solid-state matrix-analytes sample, of matrix dimers. These species are formed by the interaction of carboxylic groups present in the matrix molecules with the formation of strong hydrogen bonds. Theoretical calculations proved that the laser irradiation of these structures leads to one or two H-bridge cleavages, giving rise to an "open" dimer structure or to disproportionation with the formation of MH(+) and [M-H](-) species. The ions so formed can be considered highly effective in their reaction with analyte ions, leading to their protonation (or deprotonation). To achieve further evidence for these proposals, in the present study the energetics of the reactions of ions from different aromatic carboxylic acids with two amino acids (glycine and lysine) and three multipeptides (gly-gly, gly-gly-gly and gly-gly-gly-gly) was investigated. The lowest ∆G values were obtained for 2,5- dihydroxybenzoic acid, widely employed as the MALDI matrix. Also, for p-nitrobenzoic acid the reaction is slightly exothermic, while for the other aromatic carboxylic acids derivatives positives values of ∆G are present.
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Affiliation(s)
- Pietro Traldi
- National Council of Researches, Institute for Energetics and Interphases, Corso Stati Uniti 4, 35100 Padua, Italy.
| | - Laura Molin
- National Council of Researches, Institute for Energetics and Interphases, Corso Stati Uniti 4, 35100 Padua, Italy.
| | - Sara Crotti
- Experimental and Clinical Pharmacology Unit, Centro di Riferimento Oncologico - National Cancer Institute, Aviano PN, Italy.
| | - Roberta Seraglia
- National Council of Researches, Institute for Energetics and Interphases, Corso Stati Uniti 4, 35100 Padua, Italy.
| | - Zbigniew Czarnocki
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
| | - Joanna Szawkało
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland.
| | - Jan K Maurin
- National Medicines Institute, Chełmska 30/34, 00-725 Warsaw, Poland. National Centre for Nuclear Research, 05- 400 Otwock, Świerk, Poland.
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