1
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Dalgic MS, Weidner S. Solvent-free sample preparation for matrix-assisted laser desorption/ionization time-of-flight mass spectrometry of polymer blends. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2024; 38:e9756. [PMID: 38616296 DOI: 10.1002/rcm.9756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Revised: 03/22/2024] [Accepted: 03/25/2024] [Indexed: 04/16/2024]
Abstract
RATIONALE Solvent-free sample preparation offers some advantages over solvent-based techniques, such as improved accuracy, reproducibility and sensitivity, for matrix-assisted laser desorption/ionization (MALDI) analysis. However, little or no information is available on the application of solvent-free techniques for the MALDI analysis of polymer blends. METHODS Solvent-free sample preparation by ball milling was applied with varying sample-to-matrix ratios for MALDI time-of-flight mass spectrometry analysis of various polymers, including polystyrenes, poly(methyl methacrylate)s and poly(ethylene glycol)s. The peak intensity ratios were compared with those obtained after using the conventional dried droplet sample preparation method. In addition, solvent-assisted milling was also applied to improve sample homogeneities. RESULTS Depending on the sample preparation method used, different peak intensity ratios were found, showing varying degrees of suppression of the signal intensities of higher mass polymers. Ball milling for up to 30 min was required to achieve constant intensity ratios indicating homogeneous mixtures. The use of wet-assisted grinding to improve the homogeneity of the blends was found to be disadvantageous as it caused partial degradation and mass-dependent segregation of the polymers in the vials. CONCLUSIONS The results clearly show that solvent-free sample preparation must be carefully considered when applied to synthetic polymer blends, as it may cause additional problems with regard to homogeneity and stability of the blends.
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Affiliation(s)
| | - Steffen Weidner
- Bundesanstalt für Materialforschung und-prüfung - BAM, Berlin, Germany
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2
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Wesdemiotis C, Williams-Pavlantos KN, Keating AR, McGee AS, Bochenek C. Mass spectrometry of polymers: A tutorial review. MASS SPECTROMETRY REVIEWS 2024; 43:427-476. [PMID: 37070280 DOI: 10.1002/mas.21844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 03/03/2023] [Accepted: 03/17/2023] [Indexed: 06/19/2023]
Abstract
Ever since the inception of synthetic polymeric materials in the late 19th century, the number of studies on polymers as well as the complexity of their structures have only increased. The development and commercialization of new polymers with properties fine-tuned for specific technological, environmental, consumer, or biomedical applications requires powerful analytical techniques that permit the in-depth characterization of these materials. One such method with the ability to provide chemical composition and structure information with high sensitivity, selectivity, specificity, and speed is mass spectrometry (MS). This tutorial review presents and exemplifies the various MS techniques available for the elucidation of specific structural features in a synthetic polymer, including compositional complexity, primary structure, architecture, topology, and surface properties. Key to every MS analysis is sample conversion to gas-phase ions. This review describes the fundamentals of the most suitable ionization methods for synthetic materials and provides relevant sample preparation protocols. Most importantly, structural characterizations via one-step as well as hyphenated or multidimensional approaches are introduced and demonstrated with specific applications, including surface sensitive and imaging techniques. The aim of this tutorial review is to illustrate the capabilities of MS for the characterization of large, complex polymers and emphasize its potential as a powerful compositional and structural elucidation tool in polymer chemistry.
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Affiliation(s)
| | | | - Addie R Keating
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
| | - Andrew S McGee
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
| | - Calum Bochenek
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
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3
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Keating AR, Wesdemiotis C. Rapid and simple determination of average molecular weight and composition of synthetic polymers via electrospray ionization-mass spectrometry and a Bayesian universal charge deconvolution. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2023; 37:e9478. [PMID: 36669764 DOI: 10.1002/rcm.9478] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 01/17/2023] [Accepted: 01/18/2023] [Indexed: 06/17/2023]
Abstract
RATIONALE Simple, affordable, and rapid methods for identifying the molecular weight (MW) distribution and macromolecular composition of polymeric materials are limited. Current tools require extensive solvent consumption, linear calibrations, and expensive consumables. A simple method for the determination of average MW (Mn , Mw ) and chain end groups is demonstrated for synthetic homopolymer standards using direct injection electrospray ionization-mass spectrometry (ESI-MS) and an open-sourced charge deconvolution (CDC) algorithm. METHODS Five homopolymer standards in the 1-7 kDa MW range were analyzed using direct-injection ESI-MS on a quadrupole/time-of-flight mass spectrometer. The samples investigated, viz. two poly(ethylene oxide) (PEO) and two poly(styrene sulfonic acid) (PSS) standards with narrow polydispersity and one poly(d,l-alanine) (pAla) standard with undefined polydispersity, were chosen to illustrate challenges with ESI-MS quantitation. Using the UniDec program, weight average MWs (Mw ) obtained from the charge-deconvoluted spectra were compared to the reported Mw data of the standards from size exclusion chromatography (SEC) measurements. RESULTS The MW data derived for the PSS, PEO, and pAla standards agreed well with the corresponding reported Mw or MW range values. The method was able to provide MW, degree of polymerization (DP), and polydispersity index (PDI) information for polymers with narrow (PSS, PEO) as well as broader (pAla) molecular weight distribution; this feature provides an advantage over MW analysis via matrix-assisted laser desorption/ionization (MALDI) for ESI-compatible materials. PSS standards differing in average MW by only a few repeat units could be confidently distinguished. Additionally, the oligomeric resolution observed for all samples studied unveiled chain-end information not available through chromatographic analysis. CONCLUSIONS Overall, the free and easy-to-use UniDec CDC algorithm provides a simple, alternative method to measuring MW and DP for polymeric materials without high solvent consumption, expensive ionization sources, or calibration curves. Information about the masses of individual oligomers and the possibility to further characterize these oligomers using tandem mass spectrometry and/or ion mobility techniques constitutes additional benefits of this approach vis-à-vis traditional MW and PDI elucidation through SEC.
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Affiliation(s)
- Addie R Keating
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
| | - Chrys Wesdemiotis
- Department of Chemistry, The University of Akron, Akron, Ohio, USA
- School of Polymer Science and Polymer Engineering, The University of Akron, Akron, Ohio, USA
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4
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Sun A'B, Li S, Kou X. Applications of MALDI-TOF-MS in structural characterization of synthetic polymers. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2023; 15:868-883. [PMID: 36745057 DOI: 10.1039/d2ay01583h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
In recent years, matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has been utilized to rapidly and precisely characterize the detailed molecular structures of synthetic polymers. This review summarizes recent progress regarding MALDI-TOF-MS for the characterization of synthetic polymers with a focus on specific important experimental aspects including sample preparation, the choice of matrix, the effects of cationizing agents and solvents, data processing and various applications. Finally, the recent trend of MALDI-TOF-MS development is discussed. We hope this review will be instructive for graduate students and junior users who need to use MALDI-TOF-MS as a necessary characterization technique for new synthetic polymers.
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Affiliation(s)
- A 'Bin Sun
- Shandong Provincial Education Department, Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Siting Li
- Shandong Provincial Education Department, Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
| | - Xinhui Kou
- Shandong Provincial Education Department, Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao, 266042, China
- Analyses and Testing Center, Qingdao University of Science and Technology, Qingdao 266042, China.
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5
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Saller KM, Pernusch DC, Schwarzinger C. MALINTO: A New MALDI Interpretation Tool for Enhanced Peak Assignment and Semiquantitative Studies of Complex Synthetic Polymers. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2023; 34:293-303. [PMID: 36599090 PMCID: PMC9896554 DOI: 10.1021/jasms.2c00311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 06/17/2023]
Abstract
The newly developed MALDI interpretation tool ("MALINTO") allows for the accelerated characterization of complex synthetic polymers via MALDI mass spectrometry. While existing software provides solutions for simple polymers like poly(ethylene glycol), polystyrene, etc., they are limited in their application on polycondensates synthesized from two different kinds of monomers (e.g., diacid and diol in polyesters). In addition to such A2 + B2 polycondensates, MALINTO covers branched and even multicyclic polymer systems. Since the MALINTO software works based on input data of monomers/repeating units, end groups, and adducts, it can be applied on polymers whose components are previously known or elucidated. Using these input data, a list with theoretically possible polymer compositions and resulting m/z values is calculated, which is further compared to experimental mass spectrometry data. For optional semiquantitative studies, peak areas are allocated according to their assigned polymer composition to evaluate both comonomer and terminating group ratios. Several tools are implemented to avoid mistakes, for example, during peak assignment. In the present publication, the functions of MALINTO are described in detail and its broad applicability on different linear polymers as well as branched and multicyclic polycondensates is demonstrated. Fellow researchers will benefit from the accelerated peak assignment using the freely available MALINTO software and might be encouraged to explore the potential of MALDI mass spectrometry for (semi)quantitative applications.
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Affiliation(s)
- Klara M. Saller
- Institute
for Chemical Technology of Organic Materials, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040Linz, Austria
| | - Daniel C. Pernusch
- Institute
for Chemical Technology of Organic Materials, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040Linz, Austria
| | - Clemens Schwarzinger
- Institute
for Chemical Technology of Organic Materials, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040Linz, Austria
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6
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Muyizere T, Mukiza J. Progress on the development of a metal salt-assisted ionization source for the mass spectrometric analysis of polymers. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2022; 14:2803-2819. [PMID: 35848110 DOI: 10.1039/d2ay00724j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The mass spectrometric analysis of polymers has been addressed as a challenging research topic due to poor ionization and complicated analysis using conventional mass spectrometry. The ionization source has demonstrated a promising future in rapid mass spectrometric analysis. Soft ionization techniques, such as electrospray ionization (ESI) and matrix-assisted laser desorption/ionization (MALDI) are the most ionization sources appeared to be a powerful tools for polymer characterization when combined with MS. However, they always need metal salts to be introduced during the ionization protocol for polymers due to the crucial role played by their ions (cations and anions). The current review focuses on the progress in the development of metal ion-assisted-ionization sources for the mass spectrometric analysis of polymers. Different ionization systems are comprehensively reviewed. The application of metal ion-assisted ESI, nanoESI, PSI, and MALDI-MS for polymer sample analyses is systematically discussed. The future research trends and challenges in this cutting-edge research field are summarized. It also aims to provide the current state-of-the-art of metal salts as a platform for ionization systems for the mass spectrometric characterization of polymers and offers the current challenges and perspectives on the promising future to improve analytical performance in this field. Finally, this mini-review provides a comprehensive handbook to researchers from different research backgrounds wishing to work in this area.
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Affiliation(s)
- Theoneste Muyizere
- University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100039, China
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology, No. 11 Beiyitiao, Zhongguancun, 100190 Beijing, China.
| | - Janvier Mukiza
- Rwanda Food and Drugs Authority, Kigali 1948, Rwanda.
- School of Education, College of Education, University of Rwanda, P. O. BOX 55, Rwamagana, Rwanda
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7
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Nanostructured Layer of Silver for Detection of Small Biomolecules in Surface-Assisted Laser Desorption Ionization Mass Spectrometry. MATERIALS 2022; 15:ma15124076. [PMID: 35744134 PMCID: PMC9227941 DOI: 10.3390/ma15124076] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 05/30/2022] [Accepted: 06/06/2022] [Indexed: 02/01/2023]
Abstract
A facile approach for the synthesis of a silver nanostructured layer for application in surface-assisted laser desorption/ionization mass spectrometry of low-molecular-weight biomolecules was developed using electrochemical deposition. The deposition was carried out using the following silver salts: trifluoroacetate, acetate and nitrate, varying the voltage and time. The plate based on trifluoroacetate at 10 V for 15 min showed intense SALDI-MS responses for standards of various classes of compounds: fatty acids, cyclitols, saccharides and lipids at a concentration of 1 nmol/spot, with values of the signal-to-noise ratio ≥50. The values of the limit of detection were 0.71 µM for adonitol, 2.08 µM for glucose and 0.39 µM for palmitic acid per spot. SEM analysis of the plate showed anisotropic flower-like microstructures with nanostructures on their surface. The reduced chemical background in the low-mass region can probably be explained by the absence of stabilizers and reducing agents during the synthesis. The plate synthesized with the developed approach showed potential for future use in the analysis of low-molecular-weight compounds of biological relevance. The absence of the need for the utilization of sophisticated equipment and the synthesis time (10 min) may benefit large-scale applications of the layer for the detection of various types of small biomolecules.
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8
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Chagunda IC, Russell GT, McIndoe JS. The signal-to-noise issue in mass spectrometric analysis of polymers. Polym Chem 2021. [DOI: 10.1039/d1py00461a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Mass spectrometric approaches to polymer analysis become increasingly ineffective as average molecular weight increases. This perspective explains these fundamental limits of MS for determining molecular weight distribution of high polymers.
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Affiliation(s)
| | - Gregory T. Russell
- School of Physical and Chemical Sciences
- University of Canterbury
- Christchurch 8140
- New Zealand
| | - J. Scott McIndoe
- Department of Chemistry
- University of Victoria
- Canada
- School of Physical and Chemical Sciences
- University of Canterbury
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9
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Elliott LA, Kinsel ME, Kinsel GR. Investigations of the Equilibrium Conditions in Plumes of Laser Desorbed Sinapic Acid with Amino Acid Analytes: Influence of Sample Preparation and Matrix to Analyte Ratio. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:2321-2327. [PMID: 33103892 DOI: 10.1021/jasms.0c00266] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The equilibrium nature of a plume of laser desorbed material is examined through the application of a previously developed thermodynamic model to the ion signals observed in 337 nm MALDI mass spectra of mixtures of the matrix sinapic acid with the amino acids alanine, valine, isoleucine, and phenylalanine. Samples are prepared using both conventional dried-droplet and solvent-free methods for comparison. The relative yield of protonated amino acid is shown to increase as the amino acid gas-phase basicity increases for both sample preparation methods. Matrix gas phase basicity values extracted from the equilibrium plots are shown to be in good agreement ([M - H+]• 876 kJ/mol and [M] 879 kJ/mol) with published experimental values supporting a mechanism wherein the protonated sinapic acid and/or the matrix radical cation act as the proton donor species. These experiments further reveal that there is a large difference in the extracted plume effective temperatures with the solvent-free method yielding lower effective temperatures as compared to the dried-droplet sample preparation, e.g., 552 K versus 1296 K, respectively, at M/A 1:1 (mole/mole). In addition, these experiments suggest that plume effective temperatures decrease as the relative amount of matrix deposited with the analyte increases, regardless of the sample preparation method. Cumulatively, these observations suggest that the crystalline solid allows more efficient transfer of the photoexcitation energy during the sample desorption step, as compared to the solvent-free sample, and/or collisional cooling is more effective for the plume of material desorbed from the solvent-free sample as compared to the conventional dried-droplet sample.
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Affiliation(s)
- Lee A Elliott
- Department of Chemistry & Biochemistry, Southern Illinois University, 1245 Lincoln Drive, Carbondale, Illinois 62901, United States
| | - Mary E Kinsel
- Department of Chemistry & Biochemistry, Southern Illinois University, 1245 Lincoln Drive, Carbondale, Illinois 62901, United States
| | - Gary R Kinsel
- Department of Chemistry & Biochemistry, Southern Illinois University, 1245 Lincoln Drive, Carbondale, Illinois 62901, United States
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10
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Fouquet TNJ. The Kendrick analysis for polymer mass spectrometry. JOURNAL OF MASS SPECTROMETRY : JMS 2019; 54:933-947. [PMID: 31758605 DOI: 10.1002/jms.4480] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 05/16/2023]
Abstract
The mass spectrum of a polymer often displays repetitive patterns with peak series spaced by the repeating unit(s) of the polymeric backbones, sometimes complexified with different adducts, chain terminations, or charge states. Exploring the complex mass spectral data or filtering the unwanted signal is tedious whether performed manually or automatically. In contrast, the now 60-year-old Kendrick (mass defect) analysis, when adapted to polymer ions, produces visual two-dimensional maps with intuitive alignments of the repetitive patterns and favourable deconvolution of features overlaid in the one-dimensional mass spectrum. This special feature article reports on an up-to-date and theoretically sound use of Kendrick plots as a data processing tool. The approach requires no prior knowledge of the sample but offers promising dynamic capabilities for visualizing, filtering, and sometimes assigning congested mass spectra. Examples of applications of the approach to polymers are discussed throughout the text, but the same tools can be readily extended to other applications, including the analysis of polymers present as pollutants/contaminants, and to other analytes incorporating a repetitive moiety, for example, oils or lipids. In each of these instances, data processing can benefit from the application of an updated and interactive Kendrick analysis.
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Affiliation(s)
- Thierry N J Fouquet
- Research Institute for Sustainable Chemistry (RISC), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
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11
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Butowska K, Kozak W, Zdrowowicz M, Makurat S, Rychłowski M, Hać A, Herman-Antosiewicz A, Piosik J, Rak J. Cytotoxicity of doxorubicin conjugated with C60 fullerene. Structural and in vitro studies. Struct Chem 2019. [DOI: 10.1007/s11224-019-01428-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Abstract
Conjugating an anticancer drug of high biological efficacy but large cytotoxicity with a “transporting” molecule of low toxicity constitutes a valuable approach to design safe drug delivery system. In the present study, doxorubicin (DOX) a drug of large cardiotoxicity was chemically conjugated to a C60-fullerene. The synthesized molecule, a fullerene-doxorubicin conjugate (Ful-DOX), was characterized using the 1H NMR and MALDI TOF mass spectrometry. The absorption and fluorescence spectra and dynamic light scattering of the conjugate were recorded in an aqueous solution, while the impact on viability of several cancer cell lines of the free DOX and the conjugate was compared using the SRB and WST-1 assays. A low antiproliferative activity of the conjugate as compared to the free DOX is a consequence of the presence of fullerene moiety in the former, which is also responsible for the conjugate aggregation in an aqueous solution. Unlike free DOX, these aggregates cannot pass through the nuclear membrane (as demonstrated by the confocal microscopy measurements), which makes them marginally cytotoxic.
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12
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Complementarity of Matrix- and Nanostructure-Assisted Laser Desorption/Ionization Approaches. NANOMATERIALS 2019; 9:nano9020260. [PMID: 30769830 PMCID: PMC6410089 DOI: 10.3390/nano9020260] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/08/2019] [Accepted: 02/11/2019] [Indexed: 01/06/2023]
Abstract
In recent years, matrix-assisted laser desorption/ionization (MALDI) has become the main tool for the study of biological macromolecules, such as protein nano-machines, especially in the determination of their molecular masses, structure, and post-translational modifications. A key role in the classical process of desorption and ionization of the sample is played by a matrix, usually a low-molecular weight weak organic acid. Unfortunately, the interpretation of mass spectra in the mass range of below m/z 500 is difficult, and hence the analysis of low molecular weight compounds in a matrix-assisted system is an analytical challenge. Replacing the classical matrix with nanomaterials, e.g., silver nanoparticles, allows improvement of the selectivity and sensitivity of spectrometric measurement of biologically important small molecules. Nowadays, the nanostructure-assisted laser desorption/ionization (NALDI) approach complements the classic MALDI in the field of modern bioanalytics. In particular, the aim of this work is to review the recent advances in MALDI and NALDI approaches.
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Nakamura S, Cody RB, Sato H, Fouquet T. Graphical Ranking of Divisors to Get the Most out of a Resolution-Enhanced Kendrick Mass Defect Plot. Anal Chem 2018; 91:2004-2012. [DOI: 10.1021/acs.analchem.8b04371] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sayaka Nakamura
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8560, Japan
| | - Robert B. Cody
- JEOL USA Inc., Peabody, Massachusetts 01960, United States
| | - Hiroaki Sato
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8560, Japan
| | - Thierry Fouquet
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8560, Japan
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14
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Tao M, Zhang L, Guo Y. Dual-Channel Enzymatic Inhibition Measurement (DEIM) Coupling Isotope Substrate via Matrix-Assisted Laser Desorption/Ionization Time of Flight Mass Spectrometry. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2018; 29:2427-2435. [PMID: 30159674 DOI: 10.1007/s13361-018-2054-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2018] [Revised: 07/20/2018] [Accepted: 08/04/2018] [Indexed: 06/08/2023]
Abstract
A novel dual-channel enzymatic inhibition measurement (DEIM) method was developed to improve the repeatability with light/heavy isotope substrates, producing reliable relative standard deviations (< 3%) by employing acetylcholinesterase (AChE) as the model enzyme. The matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) was adapted for enzyme-inhibited method due to its good salt-tolerance and high throughput; meanwhile, dual-channel enzymatic reactions were performed to improve the repeatability of each well. The acetylcholinesterase inhibition measurement was conducted by mixing the quenched enzyme reaction solution of blank group (with heavy isotope as substrate) and experimental group (with light isotope as substrate), of which the inhibition rate might be affected by isotope effects. Hence, inverse study and Km measurement were implemented to validate the method. The inverse study shows similar inhibition rate (68.9 and 70.3%) and the Km of isotope substrates are analogous (0.139 and 0.135 mM), which demonstrated that the novel method is feasible to AChE inhibition measurement. Finally, the method was applied to herb extracts, half of which exhibit inhibition to AChE. The precise dual-channel enzymatic inhibition measurement (DEIM) method could be regarded as a promising approach to potential enzyme inhibitor screening. Graphical Abstract ᅟ.
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Affiliation(s)
- Min Tao
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, Center for Excellence in Molecular Synthesis, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, People's Republic of China
- Postdoctoral Programme, Mayinglong Pharmaceutical Group Co. Ltd., Wuhan, People's Republic of China
| | - Li Zhang
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, Center for Excellence in Molecular Synthesis, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, People's Republic of China.
| | - Yinlong Guo
- State Key Laboratory of Organometallic Chemistry and National Center for Organic Mass Spectrometry in Shanghai, Shanghai Institute of Organic Chemistry, Center for Excellence in Molecular Synthesis, University of Chinese Academy of Sciences, Chinese Academy of Sciences, 345 Lingling Road, Shanghai, 200032, People's Republic of China.
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15
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Calvano CD, Monopoli A, Cataldi TRI, Palmisano F. MALDI matrices for low molecular weight compounds: an endless story? Anal Bioanal Chem 2018; 410:4015-4038. [DOI: 10.1007/s00216-018-1014-x] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 02/27/2018] [Accepted: 03/08/2018] [Indexed: 10/17/2022]
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16
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Zhang W, Abdulkarim A, Golling FE, Räder HJ, Müllen K. Cycloparaphenylenes and Their Catenanes: Complex Macrocycles Unveiled by Ion Mobility Mass Spectrometry. Angew Chem Int Ed Engl 2017; 56:2645-2648. [DOI: 10.1002/anie.201611943] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Indexed: 11/11/2022]
Affiliation(s)
- Wen Zhang
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
| | - Ali Abdulkarim
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
| | - Florian E. Golling
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
- Present address: Covestro AG; 51365 Leverkusen Germany
| | - Hans Joachim Räder
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
| | - Klaus Müllen
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
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17
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Zhang W, Abdulkarim A, Golling FE, Räder HJ, Müllen K. Cycloparaphenylenes and Their Catenanes: Complex Macrocycles Unveiled by Ion Mobility Mass Spectrometry. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201611943] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Wen Zhang
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
| | - Ali Abdulkarim
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
| | - Florian E. Golling
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
- Present address: Covestro AG; 51365 Leverkusen Germany
| | - Hans Joachim Räder
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
| | - Klaus Müllen
- Max Planck Institute for Polymer Research; Ackermannweg 10 55128 Mainz Germany
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Wang CC, Lai YH, Ou YM, Chang HT, Wang YS. Critical factors determining the quantification capability of matrix-assisted laser desorption/ionization- time-of-flight mass spectrometry. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2016; 374:rsta.2015.0371. [PMID: 27644968 PMCID: PMC5031637 DOI: 10.1098/rsta.2015.0371] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/17/2016] [Indexed: 05/03/2023]
Abstract
Quantitative analysis with mass spectrometry (MS) is important but challenging. Matrix-assisted laser desorption/ionization (MALDI) coupled with time-of-flight (TOF) MS offers superior sensitivity, resolution and speed, but such techniques have numerous disadvantages that hinder quantitative analyses. This review summarizes essential obstacles to analyte quantification with MALDI-TOF MS, including the complex ionization mechanism of MALDI, sensitive characteristics of the applied electric fields and the mass-dependent detection efficiency of ion detectors. General quantitative ionization and desorption interpretations of ion production are described. Important instrument parameters and available methods of MALDI-TOF MS used for quantitative analysis are also reviewed.This article is part of the themed issue 'Quantitative mass spectrometry'.
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Affiliation(s)
- Chia-Chen Wang
- Department of Biochemistry, National Yang-Ming University, No. 155, Section 2, Linong Street, Taipei 112, Taiwan, Republic of China Genomics Research Center, Academia Sinica, 128 Academia Road, Section 2, Taipei 115, Taiwan, Republic of China
| | - Yin-Hung Lai
- Genomics Research Center, Academia Sinica, 128 Academia Road, Section 2, Taipei 115, Taiwan, Republic of China
| | - Yu-Meng Ou
- Genomics Research Center, Academia Sinica, 128 Academia Road, Section 2, Taipei 115, Taiwan, Republic of China Department of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan, Republic of China
| | - Huan-Tsung Chang
- Department of Chemistry, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan, Republic of China
| | - Yi-Sheng Wang
- Department of Biochemistry, National Yang-Ming University, No. 155, Section 2, Linong Street, Taipei 112, Taiwan, Republic of China Genomics Research Center, Academia Sinica, 128 Academia Road, Section 2, Taipei 115, Taiwan, Republic of China
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19
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Fouquet T, Torimura M, Sato H. Multi-stage Mass Spectrometry of Poly(vinyl pyrrolidone) and Its Vinyl Succinimide Copolymer Formed upon Exposure to Sodium Hypochlorite. ACTA ACUST UNITED AC 2016; 5:A0050. [PMID: 27800293 DOI: 10.5702/massspectrometry.a0050] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Accepted: 09/26/2016] [Indexed: 11/23/2022]
Abstract
The degradation routes of poly(vinyl pyrrolidone) (PVP) exposed to sodium hypochlorite (bleach) have been previously investigated using chemical analyses such as infrared spectroscopy. So far, no reports have proposed mass spectrometry (MS) as an alternative tool despite its capability to provide molecular and structural information using its single stage electrospray (ESI) or matrix assisted laser desorption ionization (MALDI) and multi stage (MS n ) configurations, respectively. The present study thus reports on the characterization of PVP after its exposure to bleach by high resolution MALDI spiralTOF-MS and Kendrick mass defect analysis providing clues as to the formation of a vinyl pyrrolidone/vinyl succinimide copolymeric degradation product. A thorough investigation of the fragmentation pathways of PVP adducted with sodium and proton allows one main route to be described-namely the release of the pyrrolidone pendant group in a charge remote and charge driven mechanism, respectively. Extrapolating this fragmentation pathway, the oxidation of vinyl pyrrolidone into vinyl succinimide hypothesized from the single stage MS is validated by the detection of an alternative succinimide neutral loss in lieu of the pyrrolidone release in the ESI-MS n spectra of the aged PVP sample. It constitutes an example of application of multi-stage mass spectrometry for the characterization of the degradation of polymeric samples at a molecular level.
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Affiliation(s)
- Thierry Fouquet
- National Institute of Advanced Industrial Science and Technology (AIST)
| | - Masaki Torimura
- National Institute of Advanced Industrial Science and Technology (AIST)
| | - Hiroaki Sato
- National Institute of Advanced Industrial Science and Technology (AIST)
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Lee C, Lu IC, Hsu HC, Lin HY, Liang SP, Lee YT, Ni CK. Formation of Metal-Related Ions in Matrix-Assisted Laser Desorption Ionization. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1491-1498. [PMID: 27306427 DOI: 10.1007/s13361-016-1424-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 05/17/2016] [Accepted: 05/20/2016] [Indexed: 06/06/2023]
Abstract
In a study of the metal-related ion generation mechanism in matrix-assisted laser desorption ionization (MALDI), crystals of matrix used in MALDI were grown from matrix- and salt-containing solutions. The intensities of metal ion and metal adducts of the matrix ion obtained from unwashed crystals were higher than those from crystals washed with deionized water, indicating that metal ions and metal adducts of the matrix ions are mainly generated from the surface of crystals. The contributions of preformed metal ions and metal adducts of the matrix ions inside the matrix crystals were minor. Metal adducts of the matrix and analyte ion intensities generated from a mixture of dried matrix, salt, and analyte powders were similar to or higher than those generated from the powder of dried droplet crystals, indicating that the contributions of the preformed metal adducts of the matrix and analyte ions were insignificant. Correlation between metal-related ion intensity fluctuation and protonated ion intensity fluctuation was observed, indicating that the generation mechanism of the metal-related ions is similar to that of the protonated ions. Because the thermally induced proton transfer model effectively describes the generation of the protonated ions, we suggest that metal-related ions are mainly generated from the salt dissolution in the matrix melted by the laser. Graphical Abstract ᅟ.
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Affiliation(s)
- Chuping Lee
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan
| | - I-Chung Lu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
| | - Hsu Chen Hsu
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
| | - Hou-Yu Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei, 10617, Taiwan
- Department of Chemistry, National Taiwan University, Taipei, 10617, Taiwan
| | - Sheng-Ping Liang
- 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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21
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Engler MS, Crotty S, Barthel MJ, Pietsch C, Schubert US, Böcker S. Abundance correction for mass discrimination effects in polymer mass spectra. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2016; 30:1233-1241. [PMID: 28328018 DOI: 10.1002/rcm.7553] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 02/28/2016] [Accepted: 03/04/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is frequently used to analyze homo- and copolymers, i.e. for computing copolymer fingerprints. However, the oligomer abundances are influenced by mass discrimination, i.e. mass- and composition-dependent ionization. We have developed a computational method to correct the abundance bias caused by the mass discrimination. METHODS MALDI-TOFMS in combination with computational methods was used to investigate three random copolymers with different ratios of styrene and isoprene. Furthermore, equimolar high- and low-mass styrene and isoprene homopolymers (2500 and 4200 Da) were mixed and also analyzed by MALDI-TOFMS. The abundances of both copolymers and homopolymers were corrected for mass discrimination effects with our new method. RESULTS The novel computational method was integrated into the existing COCONUT software. The method was demonstrated using the measured styrene and isoprene co- and homopolymers. First, the method was applied to homopolymer spectra. Subsequently, the copolymer fingerprint was computed from the copolymer MALDI mass spectra and the correcting function applied. The changes in the composition are plausible, indicating that correction of copolymer abundances was reasonable. CONCLUSIONS Our computational method may help to avoid erroneous conclusions when analyzing copolymer MS spectra. The software is freely available and represents a step towards comprehensive computational support in polymer science. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Martin S Engler
- Chair of Bioinformatics, Friedrich Schiller University Jena, Ernst-Abbe-Platz 2, 07743, Jena, Germany
| | - Sarah Crotty
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldstr. 10, 07743, Jena, Germany
- Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldstr. 10, 07743, Jena, Germany
| | - Markus J Barthel
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldstr. 10, 07743, Jena, Germany
- Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldstr. 10, 07743, Jena, Germany
| | - Christian Pietsch
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldstr. 10, 07743, Jena, Germany
- Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldstr. 10, 07743, Jena, Germany
| | - Ulrich S Schubert
- Laboratory of Organic and Macromolecular Chemistry (IOMC), Friedrich Schiller University Jena, Humboldstr. 10, 07743, Jena, Germany
- Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldstr. 10, 07743, Jena, Germany
| | - Sebastian Böcker
- Chair of Bioinformatics, Friedrich Schiller University Jena, Ernst-Abbe-Platz 2, 07743, Jena, Germany
- Jena Center for Soft Matter (JCSM), Friedrich Schiller University Jena, Humboldstr. 10, 07743, Jena, Germany
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Hitzenberger JF, Dammann C, Lang N, Lungerich D, García-Iglesias M, Bottari G, Torres T, Jux N, Drewello T. Making the invisible visible: improved electrospray ion formation of metalloporphyrins/-phthalocyanines by attachment of the formate anion (HCOO(-)). Analyst 2016; 141:1347-55. [PMID: 26753183 DOI: 10.1039/c5an02148k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A protocol is developed for the coordination of the formate anion (HCOO(-)) to neutral metalloporphyrins (Pors) and -phthalocyanines (Pcs) containing divalent metals as a means to improve their ion formation in electrospray ionization (ESI). This method is particularly useful when the oxidation of the neutral metallomacrocycle fails. While focusing on Zn(II)Pors and Zn(II)Pcs, we show that formate is also readily attached to Mn(II), Mg(II) and Co(II)Pcs. However, for the Co(II)Pc secondary reactions can be observed. Upon collision-induced dissociation (CID), Zn(II)Por/Pc·formate supramolecular complexes can undergo the loss of CO2 in combination with transfer of a hydride anion (H(-)) to the zinc metal center. Further dissociation leads to electron transfer and hydrogen atom loss, generating a route to the radical anion of the Zn(II)Por/Pc without the need for electrochemical reduction, although the Zn(II)Por/Pc may have a too low electron affinity to allow electron transfer directly from the formate anion. In addition to single Por molecules, multi Por arrays were successfully analyzed by this method. In this case, multiple addition of formate occurs, giving rise to multiply charged species. In these multi Por arrays, complexation of the formate anion occurs by two surrounding Por units (sandwich). Therefore, the maximum attainment of formate anions in these arrays corresponds to the number of such sandwich complexes rather than the number of porphyrin moieties. The same bonding motif leads to dimers of the composition [(Zn(II)Por/Pc)2·HCOO](-). In these, the formate anion can act as a structural probe, allowing the distinction of isomeric ions with the formate bridging two macrocycles or being attached to a dimer of directly connected macrocycles.
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Affiliation(s)
- Jakob Felix Hitzenberger
- Physical Chemistry I, Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
| | - Claudia Dammann
- Physical Chemistry I, Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
| | - Nina Lang
- Organic Chemistry II, Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Henkestraße 42, 91054 Erlangen, Germany.
| | - Dominik Lungerich
- Organic Chemistry II, Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Henkestraße 42, 91054 Erlangen, Germany.
| | - Miguel García-Iglesias
- Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
| | - Giovanni Bottari
- Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain. and IMDEA-Nanociencia, c/Faraday 9, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Tomás Torres
- Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain. and IMDEA-Nanociencia, c/Faraday 9, Campus de Cantoblanco, 28049 Madrid, Spain
| | - Norbert Jux
- Organic Chemistry II, Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Henkestraße 42, 91054 Erlangen, Germany.
| | - Thomas Drewello
- Physical Chemistry I, Department of Chemistry and Pharmacy, University of Erlangen-Nuremberg, Egerlandstrasse 3, 91058 Erlangen, Germany.
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Bennour H, Fildier A, Chatti S, Kricheldorf HR, Zina MS, Medimagh R. Biosourced Cyclic and Multicyclic Polyesters Based on 1,4:3,6-Dianhydrohexitols: Application to Metal Ions Uptake in Aqueous Media. MACROMOL CHEM PHYS 2015. [DOI: 10.1002/macp.201500001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Haythem Bennour
- Laboratoire des Substances Naturelles (LSN)Institut National d'Analyse et de Recherche Physico-chimique (INRAP)Pôle technologique de Sidi Thabet; 2020 Sidi Thabet Tunisia
| | - Aurélie Fildier
- Université de Lyon; Institut des Sciences Analytiques; UMR 5280; 5 rue de la Doua 69100 Villeurbanne France
| | - Saber Chatti
- Université de Lyon; Institut des Sciences Analytiques; UMR 5280; 5 rue de la Doua 69100 Villeurbanne France
| | - Hans R. Kricheldorf
- Faculté des Science de Tunis; Université de Tunis El-Manar; 2020 Tunis Tunisia
| | - Mongia Said Zina
- Institut für Technische und Makromolekulare Chemie; Bundesstr. 45 D-22607 Hamburg Germany
| | - Raouf Medimagh
- Laboratoire des Substances Naturelles (LSN)Institut National d'Analyse et de Recherche Physico-chimique (INRAP)Pôle technologique de Sidi Thabet; 2020 Sidi Thabet Tunisia
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24
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Fouquet T, Fetzer L, Mertz G, Puchot L, Verge P. Photoageing of cardanol: characterization, circumvention by side chain methoxylation and application for photocrosslinkable polymers. RSC Adv 2015. [DOI: 10.1039/c5ra02858b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Photoageing of cardanol and its limitation by methoxylation of the side chain to produce photocrosslinkable copolymers of tunable reactivity.
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Affiliation(s)
- T. Fouquet
- Luxembourg Institute of Science and Technology (LIST)
- 4362 Esch/Alzette
- Luxembourg
| | - L. Fetzer
- Luxembourg Institute of Science and Technology (LIST)
- 4362 Esch/Alzette
- Luxembourg
| | - G. Mertz
- Luxembourg Institute of Science and Technology (LIST)
- 4362 Esch/Alzette
- Luxembourg
| | - L. Puchot
- Luxembourg Institute of Science and Technology (LIST)
- 4362 Esch/Alzette
- Luxembourg
| | - P. Verge
- Luxembourg Institute of Science and Technology (LIST)
- 4362 Esch/Alzette
- Luxembourg
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25
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Al Ghafly H, Siraj N, Das S, Regmi BP, Magut PKS, Galpothdeniya WIS, Murray KK, Warner IM. GUMBOS matrices of variable hydrophobicity for matrix-assisted laser desorption/ionization mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2014; 28:2307-2314. [PMID: 25279744 DOI: 10.1002/rcm.7027] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 08/19/2014] [Accepted: 08/24/2014] [Indexed: 06/03/2023]
Abstract
RATIONALE Detection of hydrophobic peptides remains a major obstacle for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). This stems from the fact that most matrices for MALDI are hydrophilic and therefore have low affinities for hydrophobic peptides. Herein, 1-aminopyrene (AP) and AP-derived group of uniform materials based on organic salts (GUMBOS) as novel matrices for MALDI-MS analyses of peptides were investigated for hydrophobic and hydrophilic peptides. METHODS A number of solid-phase AP-based GUMBOS are synthesized with variable hydrophobicity simply by changing the counterions. Structures were confirmed by use of (1)H NMR and electrospray ionization mass spectrometry (ESI-MS). 1-Octanol/water partition coefficients (Ko/w) were used to measure the hydrophobicity of the matrices. A dried-droplet method was used for sample preparation. All spectra were obtained using a MALDI-TOF mass spectrometer in positive ion reflectron mode. RESULTS A series of AP-based GUMBOS was synthesized including [AP][chloride] ([AP][Cl]), [AP][ascorbate] ([AP][Asc]) and [AP][bis(trifluoromethane)sulfonimide] ([AP][NTf2]). The relative hydrophobicities of these compounds and α-cyano-4-hydroxycinnamic acid (CHCA, a common MALDI matrix) indicated that AP-based GUMBOS can be tuned to be much more hydrophobic than CHCA. A clear trend is observed between the signal intensities of hydrophobic peptides and hydrophobicity of the matrix. CONCLUSIONS MALDI matrices of GUMBOS with tunable hydrophobicities are easily obtained simply by varying the counterion. We have found that hydrophobic matrix materials are very effective for MALDI determination of hydrophobic peptides and, similarly, the more hydrophilic peptides displayed greater intensity in the more hydrophilic matrix.
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Affiliation(s)
- Hashim Al Ghafly
- Department of Chemistry, Louisiana State University, Baton Rouge, LA, 70803, USA
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26
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Exploration of cardanol-based phenolated and epoxidized resins by size exclusion chromatography and MALDI mass spectrometry. Anal Chim Acta 2014; 843:46-58. [PMID: 25150696 DOI: 10.1016/j.aca.2014.07.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 07/15/2014] [Accepted: 07/19/2014] [Indexed: 11/22/2022]
Abstract
Cardanol and cardanol derivatives are among the most important biobased materials currently investigated in green chemistry, as renewable and promising building blocks in lieu of traditional raw materials from non renewable resources, in particular owing to the olefinic linkages on the C15 alkyl side-chain. Despite the increasing interest they arouse, analytical chemistry dedicated to cardanol and associated resins has been rarely reported in the literature, found even poorer when dealing with chromatography and mass spectrometry. In this work, a thorough molecular characterization was conducted using matrix assisted laser desorption ionization (MALDI) mass spectrometry, size exclusion chromatography (SEC), and SEC-MALDI coupling to gain insights into the composition of phenolated, epoxidized, and epoxidized phenolated cardanol. A nomenclature was proposed to properly describe the numerous species found in these materials, while simulations of the unsaturation patterns and their comparison with the detected patterns in MALDI-MS gave useful details about the phenolation treatment expected to occur on the polyunsaturated C15 side chain. Finally, the SEC-MALDI off-line coupling allowed SEC peaks to be deconvoluted by mass spectrometry and MALDI artefacts related to matrix adduction to be pointed out.
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27
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Liu P, Forni A, Chen H. Development of Solvent-Free Ambient Mass Spectrometry for Green Chemistry Applications. Anal Chem 2014; 86:4024-32. [DOI: 10.1021/ac500527q] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Pengyuan Liu
- Center for Intelligent Chemical
Instrumentation, †Department
of Chemistry and Biochemistry, ‡Edison Biotechnology
Institute, Ohio University, Athens, Ohio 45701, United States
| | - Amanda Forni
- Center for Intelligent Chemical
Instrumentation, †Department
of Chemistry and Biochemistry, ‡Edison Biotechnology
Institute, Ohio University, Athens, Ohio 45701, United States
| | - Hao Chen
- Center for Intelligent Chemical
Instrumentation, †Department
of Chemistry and Biochemistry, ‡Edison Biotechnology
Institute, Ohio University, Athens, Ohio 45701, United States
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28
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Chen H, Dawe LN, Kozak CM. Chromium(iii) amine-bis(phenolate) complexes as catalysts for copolymerization of cyclohexene oxide and CO2. Catal Sci Technol 2014. [DOI: 10.1039/c3cy01002c] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chromium complexes of tri- and tetradentate amine-bis(phenolate) ligands in combination with chloride, azide or DMAP nucleophiles are effective catalysts for the copolymerization of CO2 with cyclohexene oxide to give polycarbonates.
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Affiliation(s)
- Hua Chen
- Department of Chemistry
- Memorial University of Newfoundland
- St. John's, Canada
| | - Louise N. Dawe
- Department of Chemistry
- Memorial University of Newfoundland
- St. John's, Canada
- C-CART X-ray Diffraction Laboratory
- Department of Chemistry
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29
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Soeriyadi AH, R.Whittaker M, Boyer C, Davis TP. Soft ionization mass spectroscopy: Insights into the polymerization mechanism. ACTA ACUST UNITED AC 2013. [DOI: 10.1002/pola.26536] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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30
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Smith MJP, Cameron NR, Mosely JA. Evaluating Atmospheric pressure Solids Analysis Probe (ASAP) mass spectrometry for the analysis of low molecular weight synthetic polymers. Analyst 2013; 137:4524-30. [PMID: 22890238 DOI: 10.1039/c2an35556f] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Atmospheric pressure Solids Analysis Probe (ASAP) mass spectrometry has facilitated the ionisation of oligomers from low molecular weight synthetic polymers, poly(ethylene glycol) (PEG: M(n) = 1430) and poly(styrene) (PS: M(n) = 1770), directly from solids, providing a fast and efficient method of identification. Ion source conditions were evaluated and it was found that the key instrument parameter was the ion source desolvation temperature which, when set to 600 °C was sufficient to vapourise the heavier oligomers for ionisation. PS, a non-polar polymer that is very challenging to analyse by MALDI or ESI without the aid of metal salts to promote cationisation, was ionised promptly by ASAP resulting in the production of radical cations. A small degree of in-source dissociation could be eliminated by control of the instrument ion source voltages. The fragmentation observed through in-source dissociation could be duplicated in a controlled manner through Collision-Induced Dissociation (CID) of the radical cations. PEG, which preferentially ionises through adduction with alkali metal cations in MALDI and ESI, was observed as a protonated molecular ion by ASAP. In-source dissociation could not be eliminated entirely and the fragmentation observed resulted from cleavage of the C-C and C-O backbone bonds, as opposed to only C-O bond cleavage observed from tandem mass spectrometry.
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Affiliation(s)
- Michael J P Smith
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, UK
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31
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Improvements to the compressed-sample (CS) technique for MALDI-TOF mass spectrometry. Anal Bioanal Chem 2012; 405:1417-24. [DOI: 10.1007/s00216-012-6529-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 10/22/2012] [Accepted: 10/26/2012] [Indexed: 10/27/2022]
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32
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Forsythe JG, Broussard JA, Lawrie JL, Kliman M, Jiao Y, Weiss SM, Webb DJ, McLean JA. Semitransparent nanostructured films for imaging mass spectrometry and optical microscopy. Anal Chem 2012; 84:10665-70. [PMID: 23146026 DOI: 10.1021/ac3022967] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Semitransparent porous silicon substrates have been developed for pairing nanostructure-initiator mass spectrometry (NIMS) imaging with traditional optical-based microscopy techniques. Substrates were optimized to generate the largest NIMS signal while maintaining sufficient transparency to allow visible light to pass through for optical microscopy. Using these substrates, both phase-contrast and NIMS images of phospholipids from a scratch-wounded cell monolayer were obtained. NIMS images were generated using a spatial resolution of 14 μm. Coupled with further improvements in spatial resolution, this approach may allow for the localization of intact biological molecules within cells without the need for labeling.
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Affiliation(s)
- Jay G Forsythe
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, USA
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33
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Li J, Inutan ED, Wang B, Lietz CB, Green DR, Manly CD, Richards AL, Marshall DD, Lingenfelter S, Ren Y, Trimpin S. Matrix assisted ionization: new aromatic and nonaromatic matrix compounds producing multiply charged lipid, peptide, and protein ions in the positive and negative mode observed directly from surfaces. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1625-43. [PMID: 22895857 DOI: 10.1007/s13361-012-0413-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 05/09/2012] [Accepted: 05/11/2012] [Indexed: 05/25/2023]
Abstract
Matrix assisted inlet ionization (MAII) is a method in which a matrix:analyte mixture produces mass spectra nearly identical to electrospray ionization without the application of a voltage or the use of a laser as is required in laserspray ionization (LSI), a subset of MAII. In MAII, the sample is introduced by, for example, tapping particles of dried matrix:analyte into the inlet of the mass spectrometer and, therefore, permits the study of conditions pertinent to the formation of multiply charged ions without the need of absorption at a laser wavelength. Crucial for the production of highly charged ions are desolvation conditions to remove matrix molecules from charged matrix:analyte clusters. Important factors affecting desolvation include heat, vacuum, collisions with gases and surfaces, and even radio frequency fields. Other parameters affecting multiply charged ion production is sample preparation, including pH and solvent composition. Here, findings from over 100 compounds found to produce multiply charged analyte ions using MAII with the inlet tube set at 450 °C are presented. Of the compounds tested, many have -OH or -NH(2) functionality, but several have neither (e.g., anthracene), nor aromaticity or conjugation. Binary matrices are shown to be applicable for LSI and solvent-free sample preparation can be applied to solubility restricted compounds, and matrix compounds too volatile to allow drying from common solvents. Our findings suggest that the physical properties of the matrix such as its morphology after evaporation of the solvent, its propensity to evaporate/sublime, and its acidity are more important than its structure and functional groups.
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Affiliation(s)
- Jing Li
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
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Barrère C, Hubert-Roux M, Lange CM, Rejaibi M, Kebir N, Désilles N, Lecamp L, Burel F, Loutelier-Bourhis C. Solvent-based and solvent-free characterization of low solubility and low molecular weight polyamides by mass spectrometry: a complementary approach. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:1347-1354. [PMID: 22555928 DOI: 10.1002/rcm.6231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
RATIONALE Polyamides (PA) belong to the most used classes of polymers because of their attractive chemical and mechanical properties. In order to monitor original PA design, it is essential to develop analytical methods for the characterization of these compounds that are mostly insoluble in usual solvents. METHODS A low molecular weight polyamide (PA11), synthesized with a chain limiter, has been used as a model compound and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). In the solvent-based approach, specific solvents for PA, i.e. trifluoroacetic acid (TFA) and hexafluoroisopropanol (HFIP), were tested. Solvent-based sample preparation methods, dried-droplet and thin layer, were optimized through the choice of matrix and salt. Solvent-based (thin layer) and solvent-free methods were then compared for this low solubility polymer. Ultra-high-performance liquid chromatography/electrospray ionization (UHPLC/ESI)-TOF-MS analyses were then used to confirm elemental compositions through accurate mass measurement. RESULTS Sodium iodide (NaI) and 2,5-dihydroxybenzoic acid (2,5-DHB) are, respectively, the best cationizing agent and matrix. The dried-droplet sample preparation method led to inhomogeneous deposits, but the thin-layer method could overcome this problem. Moreover, the solvent-free approach was the easiest and safest sample preparation method giving equivalent results to solvent-based methods. Linear as well as cyclic oligomers were observed. Although the PA molecular weights obtained by MALDI-TOF-MS were lower than those obtained by (1)H NMR and acido-basic titration, this technique allowed us to determine the presence of cyclic and linear species, not differentiated by the other techniques. TFA was shown to induce modification of linear oligomers that permitted cyclic and linear oligomers to be clearly highlighted in spectra. CONCLUSIONS Optimal sample preparation conditions were determined for the MALDI-TOF-MS analysis of PA11, a model of polyamide analogues. The advantages of the solvent-free and solvent-based approaches were shown. Molecular weight determination using MALDI was discussed.
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Affiliation(s)
- Caroline Barrère
- Université de Rouen, Laboratoire COBRA UMR 6014 & FR 3038, IRCOF, 1 Rue Tesnière, 76821 Mont St Aignan Cedex, France
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Schwarzinger C, Gabriel S, Beißmann S, Buchberger W. Quantitative analysis of polymer additives with MALDI-TOF MS using an internal standard approach. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2012; 23:1120-1125. [PMID: 22451334 DOI: 10.1007/s13361-012-0367-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 02/15/2012] [Accepted: 02/21/2012] [Indexed: 05/31/2023]
Abstract
MALDI-TOF MS is used for the qualitative analysis of seven different polymer additives directly from the polymer without tedious sample pretreatment. Additionally, by using a solid sample preparation technique, which avoids the concentration gradient problems known to occur with dried droplets and by adding tetraphenylporphyrine as an internal standard to the matrix, it is possible to perform quantitative analysis of additives directly from the polymer sample. Calibration curves for Tinuvin 770, Tinuvin 622, Irganox 1024, Irganox 1010, Irgafos 168, and Chimassorb 944 are presented, showing coefficients of determination between 0.911 and 0.990.
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Affiliation(s)
- Clemens Schwarzinger
- Institute for Chemical Technology of Organic Materials, Johannes Kepler University, Linz, Austria.
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Dössel LF, Kamm V, Howard IA, Laquai F, Pisula W, Feng X, Li C, Takase M, Kudernac T, De Feyter S, Müllen K. Synthesis and Controlled Self-Assembly of Covalently Linked Hexa-peri-hexabenzocoronene/Perylene Diimide Dyads as Models To Study Fundamental Energy and Electron Transfer Processes. J Am Chem Soc 2012; 134:5876-86. [DOI: 10.1021/ja211504a] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lukas F. Dössel
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Valentin Kamm
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Ian A. Howard
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Frédéric Laquai
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Wojciech Pisula
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Xinliang Feng
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Chen Li
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Masayoshi Takase
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Tibor Kudernac
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Steven De Feyter
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
| | - Klaus Müllen
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128
Mainz, Germany
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Kulkarni SU, Thies MC. Quantitative analysis of polydisperse systems via solvent-free matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2012; 26:392-398. [PMID: 22223328 DOI: 10.1002/rcm.5308] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Quantitative analysis of partially soluble and insoluble polydisperse materials is challenging due to the lack of both appropriate standards and reliable analytical techniques. To this end, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) incorporating a solvent-free sample preparation technique was investigated for the quantitative analysis of partially soluble, polydisperse, polycyclic aromatic hydrocarbon (PAH) oligomers. Molecular weight standards consisting of narrow molecular weight dimer and trimer oligomers of the starting M-50 petroleum pitch were produced using both dense-gas/supercritical extraction (DGE/SCE) and preparative-scale, gel permeation chromatography (GPC). The validity of a MALDI-based, quantitative analysis technique using solvent-free sample preparation was first demonstrated by applying the method of standard addition to a pitch of known composition. The standard addition method was then applied to the quantitative analysis of two insoluble petroleum pitch fractions of unknown oligomeric compositions, with both the dimer and trimer compositions of these fractions being accurately determined. To our knowledge, this study represents the first successful MALDI application of solvent-free quantitative analysis to insoluble, polydisperse materials.
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Affiliation(s)
- Sourabh U Kulkarni
- Department of Chemical and Biomolecular Engineering, Center for Advanced Engineering Fibers and Films, Clemson University, Clemson, SC 29634-0909, USA
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Hyzak L, Moos R, von Rath F, Wulf V, Wirtz M, Melchior D, Kling HW, Köhler M, Gäb S, Schmitz OJ. Quantitative Matrix-Assisted Laser Desorption Ionization-Time-of-Flight Mass Spectrometry Analysis of Synthetic Polymers and Peptides. Anal Chem 2011; 83:9467-71. [DOI: 10.1021/ac2021739] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lukas Hyzak
- Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, Gauss-Strasse 20, 42119 Wuppertal, Germany
| | - Rebecca Moos
- Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, Gauss-Strasse 20, 42119 Wuppertal, Germany
| | - Friederike von Rath
- Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, Gauss-Strasse 20, 42119 Wuppertal, Germany
| | - Volker Wulf
- BASF Personal Care and Nutrition GmbH, D-40551 Düsseldorf, Germany
| | - Michaela Wirtz
- BASF Personal Care and Nutrition GmbH, D-40551 Düsseldorf, Germany
| | - David Melchior
- BASF Personal Care and Nutrition GmbH, D-40551 Düsseldorf, Germany
| | - Hans-Willi Kling
- Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, Gauss-Strasse 20, 42119 Wuppertal, Germany
| | - Michael Köhler
- BASF Personal Care and Nutrition GmbH, D-40551 Düsseldorf, Germany
| | - Siegmar Gäb
- Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, Gauss-Strasse 20, 42119 Wuppertal, Germany
| | - Oliver J. Schmitz
- Institute for Pure and Applied Mass Spectrometry, University of Wuppertal, Gauss-Strasse 20, 42119 Wuppertal, Germany
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40
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Kulkarni SU, Räder HJ, Thies MC. The effects of molecular weight distribution and sample preparation on matrix-assisted laser desorption/ionization time-of-flight mass spectrometric analysis of petroleum macromolecules. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:2799-2808. [PMID: 21913258 DOI: 10.1002/rcm.5166] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
To date there have been no systematic, quantitative investigations of the effect of sample preparation on the matrix-assisted laser desorption/ionization time-of-flight (MALDI) mass spectrometry response for polydisperse systems. To this end, the interrelationships between sample preparation, analyte molecular weight distribution (MWD) and solubility, and signal response were investigated for mixtures of alkylated polycyclic aromatic hydrocarbon (PAH) oligomers, the constituents of petroleum pitch that serve as precursors for advanced carbon materials. These PAH oligomers served as a useful analyte system for study, as their solvent solubilities decrease significantly with each increasing oligomeric unit. Molecular weight standards consisting of relatively pure dimer and trimer cuts of the starting M-50 petroleum pitch were produced using a dense-gas/supercritical extraction (DGE/SCE) technique and were then used to produce oligomeric mixtures of well-defined composition for study. Both traditional, solvent-based and newer, solvent-free sample preparation methods were evaluated, and their effects on both homogeneity and signal response were determined. While solvent-free sample preparation methods produced homogeneous samples and reproducible results regardless of the MWD of the analyte, solvent-based samples that contained more than one oligomeric cut produced non-homogeneous samples and poor reproducibilities. The differing solubilities of dimer, trimer, and tetramer oligomers in a given solvent (e.g., CS(2) or toluene) were found to be the cause of the inhomogeneities observed in solvent-based sample preparation. A quantitative analysis study performed with dimer/trimer mixtures over a wide range of compositions via solvent-free sample preparation indicates that linear, reproducible calibration curves can be generated and used to calculate the molecular composition of unknown dimer/trimer mixtures with confidence.
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Affiliation(s)
- Sourabh U Kulkarni
- Department of Chemical and Biomolecular Engineering, Center for Advanced Engineering Fibers and Films, Clemson University, Clemson, SC 29634-0909, USA
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Mavrinskaya N, Räder HJ, Müllen K. Nonlinear behavior during semi-quantitative analysis of thin organic layers by laser desorption mass spectrometry. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:2196-2200. [PMID: 21710599 DOI: 10.1002/rcm.5102] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Characterization of the surface coverage and thickness of an organic thin film is particularly important in organic electronics and optoelectronics. For surface coverage down to the submonolayer level there is still a need for characterization methods which are easily applicable. In the present work we report on the evaluation of laser desorption mass spectrometry (LD-MS) for its use in thickness determination of organic thin films. Whereas LD-MS is well established as a soft ionization method for small molecules, its capability for use in quantitative analysis is nearly unexplored. We carried out experiments with two different molecules, 7,7,8,8-tetracyanoquinodimethane and hexabenzocoronene, in a series of experiments with increasing surface coverage. The obtained data were analyzed by plotting the LD signal intensities versus the relative layer thickness and they reveal a nonlinear behavior, which can be classified into regions of different desorption/ionization efficiencies. Visualization by atomic force microscopy reveals that the first efficiency change corresponds to the transition between incomplete and complete coverage of the metal surface by analyte molecules. A second transition is observed at high layer thickness where the signal intensity stays constant, independent of further thickness increments, and this is attributed to the limited penetration depth of the laser beam. The intermediate region between the two transitions shows a linear behavior and can thus be used for semi-quantitative thickness measurements. The efficiency change observed at the point of complete surface coverage is particularly useful for thin layer preparation of organic field effect transistors, where complete surface coverage is a minimum requirement.
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Affiliation(s)
- Natalia Mavrinskaya
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany
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So PK, Yao ZP. Oil-Assisted Sample Preparation: A Simple Method for Analysis of Solid Samples Using Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry. Anal Chem 2011; 83:5175-81. [DOI: 10.1021/ac2002593] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pui-Kin So
- State Key Laboratory for Chirosciences and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administration Region, China
| | - Zhong-Ping Yao
- State Key Laboratory for Chirosciences and Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong Special Administration Region, China
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Serrano CA, Zhang Y, Yang J, Schug KA. Matrix-assisted laser desorption/ionization mass spectrometric analysis of aliphatic biodegradable photoluminescent polymers using new ionic liquid matrices. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2011; 25:1152-1158. [PMID: 21488114 DOI: 10.1002/rcm.4974] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
In this study, two novel ionic liquid matrices (ILMs), N,N-diisopropylethylammonium 3-oxocoumarate and N,N-diisopropylethylammonium dihydroxymonooxoacetophenoate, were tested for the structural elucidation of recently developed aliphatic biodegradable polymers by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The polymers, formed by a condensation reaction of three components, citric acid, octane diol, and an amino acid, are fluorescent, but the exact mechanism behind their luminescent properties has not been fully elucidated. In the original studies, which introduced the polymer class (J. Yang et al., Proc. Natl. Acad. Sci. USA 2009, 106, 10086-10091), a hyper-conjugated cyclic structure was proposed as the source for the photoluminescent behavior. With the use of the two new ILMs, we present evidence that supports the presence of the proposed cyclization product. In addition, the new ILMs, when compared with a previously established ILM, N,N-diisopropylethylammonium α-cyano-3-hydroxycinnimate, provided similar signal intensities and maintained similar spectral profiles. This research also established that the new ILMs provided good spot-to-spot reproducibility and high ionization efficiency compared with corresponding crystalline matrix preparations. Many polymer features revealed through the use of the ILMs could not be observed with crystalline matrices. Ultimately, the new ILMs highlighted the composition of the synthetic polymers, as well as the loss of water that was expected for the formation of the proposed cyclic structure on the polymer backbone.
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Affiliation(s)
- Carlos A Serrano
- Department of Chemistry & Biochemistry, The University of Texas at Arlington, Arlington, TX 76019, USA
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44
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Wang B, Lietz CB, Inutan ED, Leach SM, Trimpin S. Producing Highly Charged Ions without Solvent Using Laserspray Ionization: A Total Solvent-Free Analysis Approach at Atmospheric Pressure. Anal Chem 2011; 83:4076-84. [DOI: 10.1021/ac2000576] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Beixi Wang
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Christopher B. Lietz
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Ellen D. Inutan
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Samantha M. Leach
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - Sarah Trimpin
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
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Weidner S, Knappe P, Panne U. MALDI-TOF imaging mass spectrometry of artifacts in “dried droplet” polymer samples. Anal Bioanal Chem 2011; 401:127-34. [DOI: 10.1007/s00216-011-4773-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 01/26/2011] [Accepted: 02/03/2011] [Indexed: 11/30/2022]
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Brandt H, Ehmann T, Otto M. Toward prediction: using chemometrics for the optimization of sample preparation in MALDI-TOF MS of synthetic polymers. Anal Chem 2011; 82:8169-75. [PMID: 20879802 DOI: 10.1021/ac101526w] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In recent years, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) has become a powerful tool for the study of synthetic polymers although its mechanism is still not understood in detail. Sample preparation plays the key role in obtaining reliable MALDI mass spectra, in particular, the proper choice of matrix, cationization reagent, and solvent. There is still no general sample preparation protocol for MALDI analysis of synthetic polymers. For known synthetic polymers, such as polystyrenes and other frequently investigated polymers, application tables in review articles might be a guide for selecting a MALDI matrix, cationization reagent, and solvent. For unknown polymers (polymers which were not analyzed by MALDI-TOF MS before but whose structures are in part known from the manufacturing process and from NMR analysis as well), the selection of matrix and solvent is based upon the polarity-similarity principle. Chemometric methods provide a useful tool for the investigation of sample preparation because huge data sets can be evaluated in short time, that is, for extracting relevant information and for classification of samples, as well. Furthermore, chemometrics provide a suitable way for the selection of a proper matrix, cationization reagent, and solvent. In this paper, a prediction model is presented using the partial least-squares (PLS) regression. By applying the model, the suitability of appropriate (nontested) combinations (matrix, cationization reagent, solvent) can be predicted for a certain synthetic polymer based upon the investigation of a few combinations. This model may help find suitable combinations in a short time and serve as a starting point for the investigation of unknown polymers. Results are exemplary presented for polystyrene PS2850.
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Affiliation(s)
- Heike Brandt
- Wacker Chemie AG, Johannes-Hess-Strasse 24, D-84489 Burghausen, Germany.
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Aminlashgari N, Hakkarainen M. Emerging Mass Spectrometric Tools for Analysis of Polymers and Polymer Additives. MASS SPECTROMETRY OF POLYMERS – NEW TECHNIQUES 2011. [DOI: 10.1007/12_2011_152] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Brandt H, Ehmann T, Otto M. Investigating the effect of mixing ratio on molar mass distributions of synthetic polymers determined by MALDI-TOF mass spectrometry using design of experiments. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2010; 21:1870-1875. [PMID: 20685132 DOI: 10.1016/j.jasms.2010.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 07/05/2010] [Accepted: 07/05/2010] [Indexed: 05/29/2023]
Abstract
It is well known that the mixing ratio affects the molar mass distribution of synthetic polymers determined by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Surely, the molar mixing ratio determines whether a mass spectrum will be obtained or not. However, depending on the mass range, several effects such as multimer formation occur, which might be a source of errors in molar mass distribution calculations. In this study, the effect of mixing ratio was investigated for several synthetic polymers, including polystyrene (PS), poly(dimethylsiloxane) (PDMS), poly(ethylene glycol) (PEG), and poly(methyl methacrylate) (PMMA) using statistical designs of experiments. The 2(3) full factorial design was found to be suitable in the study of more than 1000 samples. The obtained MALDI mass spectra as well as the ANOVA statistics show that the mixing ratio affects the molar mass distribution. The optimal mixing ratio for a defined synthetic polymer depends on the studied combination (matrix, cationization reagent, solvent).
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Trimpin S. A perspective on MALDI alternatives-total solvent-free analysis and electron transfer dissociation of highly charged ions by laserspray ionization. JOURNAL OF MASS SPECTROMETRY : JMS 2010; 45:471-485. [PMID: 20446310 DOI: 10.1002/jms.1737] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Progress in research is hindered by analytical limitations, especially in biological areas in which sensitivity and dynamic range are critical to success. Inherent difficulties of characterization associated with complexity arising from heterogeneity of various materials including topologies (isomeric composition) and insolubility also limit progress. For this reason, we are developing methods for total solvent-free analysis by mass spectrometry consisting of solvent-free ionization followed by solvent-free gas-phase separation. We also recently constructed a novel matrix-assisted laser desorption ionization (MALDI) source that provides a simple, practical and sensitive way of producing highly charged ions by laserspray ionization (LSI) or singly charged ions commonly observed with MALDI by choice of matrix or matrix preparation. This is the first ionization source with such freedom-an extremely powerful analytical 'switch'. Multiply charged LSI ions allow molecules exceeding the mass-to-charge range of the instrument to be observed and permit for the first time electron transfer dissociation fragment ion analysis.
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Affiliation(s)
- Sarah Trimpin
- Department of Chemistry, Wayne State University, Detroit, MI, USA.
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50
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Trimpin S, Herath TN, Inutan ED, Wager-Miller J, Kowalski P, Claude E, Walker JM, Mackie K. Automated solvent-free matrix deposition for tissue imaging by mass spectrometry. Anal Chem 2010; 82:359-67. [PMID: 19968249 DOI: 10.1021/ac902065u] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The ability to analyze complex (macro) molecules is of fundamental importance for understanding chemical, physical, and biological processes. Complexity may arise from small differences in structure, large dynamic range, as well as a vast range in solubility or ionization, imposing daunting tasks in areas as different as lipidomics and proteomics. Here, we describe a rapid matrix application that permits the deposition of matrix-assisted laser desorption/ionization (MALDI) matrix solvent-free. This solvent-free one-step automatic matrix deposition is achieved through vigorous movements of beads pressing the matrix material through a metal mesh. The mesh (20 mum) produces homogeneous coverage of <12 microm crystals (DHB, CHCA matrixes) in 1 min, as determined by optical microscopy, permitting fast uniform coverage of analyte and possible high-spatial resolution surface analysis. Homogenous tissue coverage of <5 microm sized crystals is achieved using a 3 microm mesh. Solvent-free MALDI analysis on a time-of-flight (TOF) mass analyzer of mouse brain tissue homogenously covered with CHCA matrix subsequently provides a homogeneous response in ion signal intensity. Total solvent-free analysis (TSA) by mass spectrometry (MS) of tissue sections is carried out by applying the MALDI matrix solvent-free for subsequent ionization and gas phase separation for decongestion of complexity in the absence of any solvent using ion mobility spectrometry (IMS) followed by MS detection. Isobaric compositions were well-delineated using TSA by MS.
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Affiliation(s)
- Sarah Trimpin
- Wayne State University, Department of Chemistry, Detroit, Michigan 48202, USA.
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