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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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Cournut A, Hosu IS, Braud F, Moustiez P, Coffinier Y, Enjalbal C, Bich C. Development of nanomaterial enabling highly sensitive surface-assisted laser desorption/ionization mass spectrometry peptide analysis. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2023; 37:e9476. [PMID: 36656736 DOI: 10.1002/rcm.9476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/14/2023] [Accepted: 01/18/2023] [Indexed: 06/17/2023]
Abstract
RATIONALE Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is an approach derived from matrix-assisted laser desorption/ionization (MALDI)-MS which overcomes the drawbacks associated with the use of organic matrices required to co-crystallize with the analytes. Indeed, nanomaterials commonly used in SALDI-MS as inert surfaces to promote desorption/ionization (D/I) ensure straightforward direct deposition of samples while providing mass spectra with ions only related to the compound of interest. The objective of this study was to develop a novel SALDI-MS approach based on steel plates that are surfaces very rapidly and easily tuned to perform the most efficient peptide detection as possible. To compare the SALDI efficacy of such metal substrates, D/I efficiency and deposit homogeneity were evaluated according to steel plate fabrication processes. METHODS The studied surfaces were nanostructured steel plates that were chemically modified by perfluorosilane and textured according to different frequencies and laser writing powers. The capacity of each tested 100 surfaces was demonstrated by comparative analyses of a mixture of standard peptides (m/z 600-3000) performed with a MALDI-TOF instrument enabling MALDI, SALDI and imaging experiments. RESULTS A peptide mix was used to screen the different surfaces depending on their D/I efficiency and their ability to ensure homogeneous deposit of the samples. For that purpose, deposition homogeneity was visualized owing to reconstructed ionic images from all protonated or sodiated ions of the 10 peptides constituting the standard mix. CONCLUSIONS Seven surfaces were then selected satisfying the required D/I efficiency and deposit homogeneity criteria. Results obtained with these optimal surfaces were then compared with those recorded by MALDI-MS analyses used as references.
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Affiliation(s)
- Aline Cournut
- Univ. Montpellier, CNRS, ENSCM, IBMM, UMR 5247, Montpellier, France
| | - Ioana Silvia Hosu
- Bioresources Department, National Institute for Research and Development in Chemistry and Petrochemistry, Bucharest, Romania
| | - Flavie Braud
- Univ. Lille, CNRS, UMR 8520 - IEMN, Lille, France
| | | | | | | | - Claudia Bich
- Univ. Montpellier, CNRS, ENSCM, IBMM, UMR 5247, Montpellier, France
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3
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Kobylis P, Kasprzyk M, Nowacki A, Caban M. An investigation of the ionicity of selected ionic liquid matrices used for matrix-assisted laser desorption/ionization. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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4
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Satoh T, Nakamura S, Fouquet T, Sato H, Ueda Y. A mass spectrometry imaging method for visualizing synthetic polymers by using average molecular weight and dispersity as indices. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2020; 34 Suppl 2:e8653. [PMID: 31721332 DOI: 10.1002/rcm.8653] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 11/05/2019] [Accepted: 11/05/2019] [Indexed: 06/10/2023]
Abstract
RATIONALE Matrix-assisted laser desorption/ionization mass spectrometric imaging (MSI) is considered to be a powerful tool for visualizing the spatial distribution of synthetic polymers. However, a conventional method extracting an image of a specific m/z value is not suitable for polymers, which have a mass distribution. It is necessary to develop the visualization method to show the spatial distribution of entire polymer series. METHODS The mass peaks included in polymer series were specified from the average mass spectrum of the entire MSI measurement region by using Kendrick mass defect analysis. The images of those mass peaks were extracted and the number average molecular weight (Mn ), the weight average molecular weight (Mw ) and dispersity (Đ) were calculated for each pixel. Finally, the spatial distribution of the polymer series was summarized to images using Mn , Mw and Đ as indices. RESULTS The effects of the methods were investigated by (i) polymers with different mass distributions and (ii) polymers with different repeat units and end-groups. In both cases, the spatial distribution of specific polymer series including several dozens to hundreds of mass peaks was summarized into three images related to Mn , Mw and Đ, which are familiar indices in polymer analysis. The results are able to provide an overview of the spatial variation of each polymer more intuitively. CONCLUSIONS The visualization of Mn , Mw and Đ will help provide an overview of the spatial distribution of polymer series combined with ion intensity distribution made by conventional methods. It can be also applied to other mass spectrometric imaging methods such as desorption electrospray ionization (DESI) or time-of-flight secondary ion mass spectrometry (TOF-SIMS).
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Affiliation(s)
| | - Sayaka Nakamura
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, 305-8565, Japan
| | - Thierry Fouquet
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, 305-8565, Japan
| | - Hiroaki Sato
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, 305-8565, Japan
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Kobylis P, Lis H, Stepnowski P, Caban M. Spectroscopic verification of ionic matrices for MALDI analysis. J Mol Liq 2019. [DOI: 10.1016/j.molliq.2019.03.137] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Trujillo-Rodríguez MJ, Nan H, Varona M, Emaus MN, Souza ID, Anderson JL. Advances of Ionic Liquids in Analytical Chemistry. Anal Chem 2018; 91:505-531. [PMID: 30335970 DOI: 10.1021/acs.analchem.8b04710] [Citation(s) in RCA: 136] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
| | - He Nan
- Department of Chemistry , Iowa State University , 1605 Gilman Hall, Ames , Iowa 50011 , United States
| | - Marcelino Varona
- Department of Chemistry , Iowa State University , 1605 Gilman Hall, Ames , Iowa 50011 , United States
| | - Miranda N Emaus
- Department of Chemistry , Iowa State University , 1605 Gilman Hall, Ames , Iowa 50011 , United States
| | - Israel D Souza
- Department of Chemistry , Iowa State University , 1605 Gilman Hall, Ames , Iowa 50011 , United States
| | - Jared L Anderson
- Department of Chemistry , Iowa State University , 1605 Gilman Hall, Ames , Iowa 50011 , United States
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7
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Rzagalinski I, Kovačević B, Hainz N, Meier C, Tschernig T, Volmer DA. Toward Higher Sensitivity in Quantitative MALDI Imaging Mass Spectrometry of CNS Drugs Using a Nonpolar Matrix. Anal Chem 2018; 90:12592-12600. [PMID: 30260620 DOI: 10.1021/acs.analchem.8b02740] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Tissue-specific ion suppression is an unavoidable matrix effect in MALDI mass spectrometry imaging (MALDI-MSI), the negative impact of which on precision and accuracy in quantitative MALDI-MSI can be reduced to some extent by applying isotope internal standards for normalization and matrix-matched calibration routines. The detection sensitivity still suffers, however, often resulting in significant loss of signal for the investigated analytes. An MSI application considerably affected by this phenomenon is the quantitative spatial analysis of central nervous system (CNS) drugs. Most of these drugs are low molecular weight, lipophilic compounds, which exhibit inefficient desorption and ionization during MALDI using conventional polar acidic matrices (CHCA, DHB). Here, we present the application of the (2-[(2 E)-3-(4- tert-butylphenyl)-2-methylprop-2-enylidene]malononitrile) matrix for high sensitivity imaging of CNS drugs in mouse brain sections. Since DCTB is usually described as an electron-transfer matrix, we provide a rationale (i.e., computational calculations of gas-phase proton affinity and ionization energy) for an additional proton-transfer ionization mechanism with this matrix. Furthermore, we compare the extent of signal suppression for five different CNS drugs when employing DCTB versus CHCA matrices. The results showed that the signal suppression was not only several times lower with DCTB than with CHCA but also depended on the specific tissue investigated. Finally, we present the application of DCTB and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry to quantitative MALDI imaging of the anesthetic drug xylazine in mouse brain sections based on a linear matrix-matched calibration curve. DCTB afforded up to 100-fold signal intensity improvement over CHCA when comparing representative single MSI pixels and >440-fold improvement for the averaged mass spectrum of the adjacent tissue sections.
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Affiliation(s)
- Ignacy Rzagalinski
- Institute of Bioanalytical Chemistry , Saarland University , 66123 Saarbrücken , Germany
| | - Borislav Kovačević
- Group for Computational Life Sciences , Ruđer Bošković Institute , 10000 Zagreb , Croatia
| | - Nadine Hainz
- Institute of Anatomy and Cell Biology , Saarland University , 66421 Homburg , Germany
| | - Carola Meier
- Institute of Anatomy and Cell Biology , Saarland University , 66421 Homburg , Germany
| | - Thomas Tschernig
- Institute of Anatomy and Cell Biology , Saarland University , 66421 Homburg , Germany
| | - Dietrich A Volmer
- Department of Chemistry , Humboldt University of Berlin , 12489 Berlin , Germany
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Abdelhamid HN. Ionic Liquid-Assisted Laser Desorption/Ionization-Mass Spectrometry: Matrices, Microextraction, and Separation. Methods Protoc 2018; 1:E23. [PMID: 31164566 PMCID: PMC6526421 DOI: 10.3390/mps1020023] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 06/13/2018] [Accepted: 06/15/2018] [Indexed: 12/16/2022] Open
Abstract
Ionic liquids (ILs) have advanced a variety of applications, including matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS). ILs can be used as matrices and solvents for analyte extraction and separation prior to analysis using laser desorption/ionization-mass spectrometry (LDI-MS). Most ILs show high stability with negligible sublimation under vacuum, provide high ionization efficiency, can be used for qualitative and quantitative analyses with and without internal standards, show high reproducibility, form homogenous spots during sampling, and offer high solvation efficiency for a wide range of analytes. Ionic liquids can be used as solvents and pseudo-stationary phases for extraction and separation of a wide range of analytes, including proteins, peptides, lipids, carbohydrates, pathogenic bacteria, and small molecules. This review article summarizes the recent advances of ILs applications using MALDI-MS. The applications of ILs as matrices, solvents, and pseudo-stationary phases, are also reviewed.
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Clark KD, Emaus MN, Varona M, Bowers AN, Anderson JL. Ionic liquids: solvents and sorbents in sample preparation. J Sep Sci 2017; 41:209-235. [DOI: 10.1002/jssc.201700864] [Citation(s) in RCA: 99] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 09/12/2017] [Accepted: 09/12/2017] [Indexed: 12/15/2022]
Affiliation(s)
- Kevin D. Clark
- Department of Chemistry; Iowa State University; Ames IA USA
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10
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Organic matrices, ionic liquids, and organic matrices@nanoparticles assisted laser desorption/ionization mass spectrometry. Trends Analyt Chem 2017. [DOI: 10.1016/j.trac.2017.01.012] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Kooijman PC, Kok S, Honing M. Independent assessment of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) sample preparation quality: Effect of sample preparation on MALDI-MS of synthetic polymers. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2017; 31:362-370. [PMID: 27870135 DOI: 10.1002/rcm.7798] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 11/17/2016] [Accepted: 11/18/2016] [Indexed: 06/06/2023]
Abstract
RATIONALE Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) provides detailed and in-depth information about the molecular characteristics of synthetic polymers. To obtain the most accurate results the sample preparation parameters should be chosen to suit the sample and the aim of the experiment. Because the underlying principles of MALDI are still not fully known, a priori determination of optimal sample preparation protocols is often not possible. METHODS Employing an automated sample preparation quality assessment method recently presented by us we quantified the sample preparation quality obtained using various sample preparation protocols. Six conventional matrices with and without added potassium as a cationization agent and six ionic liquid matrices (ILMs) were assessed using poly(ethylene glycol) (PEG), polytetrahydrofuran (PTHF) and poly(methyl methacrylate) (PMMA) as samples. All sample preparation protocols were scored and ranked based on predefined quality parameters and spot-to-spot repeatability. RESULTS Clearly distinctive preferences were observed in matrix identity and cationization agent for PEG, PTHF and PMMA, as the addition of an excess of potassium cationization agent results in an increased score for PMMA and a contrasting matrix-dependent effect for PTHF and PEG. The addition of excess cationization agent to sample mixtures dissipates any overrepresentation of high molecular weight polymer species. Our results show reduced ionization efficiency and similar sample deposit homogeneity for all tested ILMs, compared with well-performing conventional MALDI matrices. CONCLUSIONS The results published here represent a start in the unsupervised quantification of sample preparation quality for MALDI samples. This method can select the best sample preparation parameters for any synthetic polymer sample and the results can be used to formulate hypotheses on MALDI principles. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Pieter C Kooijman
- DSM Resolve, Urmonderbaan 22, 6167 RD, Geleen, The Netherlands
- Division of BioAnalytical Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands
- M4I Institute, Maastricht University, Universiteitssingel 50, 6229 ER, Maastricht, The Netherlands
| | - Sander Kok
- DSM Resolve, Urmonderbaan 22, 6167 RD, Geleen, The Netherlands
| | - Maarten Honing
- DSM Resolve, Urmonderbaan 22, 6167 RD, Geleen, The Netherlands
- Division of BioAnalytical Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV, Amsterdam, The Netherlands
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12
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Wu T, Zhang C, Ren H, Xi Y, Du Y, Peng Y. Solvent effect in polymer analysis by MALDI-TOF mass spectrometry. INTERNATIONAL JOURNAL OF POLYMER ANALYSIS AND CHARACTERIZATION 2017. [DOI: 10.1080/1023666x.2016.1263913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Ting Wu
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Chuanjing Zhang
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Hongxin Ren
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Yidan Xi
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Yiping Du
- School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai, China
| | - Yaxin Peng
- Department of Mathematics, Shanghai University, Shanghai, China
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13
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Wesdemiotis C. Multidimensional Mass Spectrometry of Synthetic Polymers and Advanced Materials. Angew Chem Int Ed Engl 2017; 56:1452-1464. [PMID: 27712048 DOI: 10.1002/anie.201607003] [Citation(s) in RCA: 71] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 10/02/2016] [Indexed: 01/06/2023]
Abstract
Multidimensional mass spectrometry interfaces a suitable ionization technique and mass analysis (MS) with fragmentation by tandem mass spectrometry (MS2 ) and an orthogonal online separation method. Separation choices include liquid chromatography (LC) and ion-mobility spectrometry (IMS), in which separation takes place pre-ionization in the solution state or post-ionization in the gas phase, respectively. The MS step provides elemental composition information, while MS2 exploits differences in the bond stabilities of a polymer, yielding connectivity and sequence information. LC conditions can be tuned to separate by polarity, end-group functionality, or hydrodynamic volume, whereas IMS adds selectivity by macromolecular shape and architecture. This Minireview discusses how selected combinations of the MS, MS2 , LC, and IMS dimensions can be applied, together with the appropriate ionization method, to determine the constituents, structures, end groups, sequences, and architectures of a wide variety of homo- and copolymeric materials, including multicomponent blends, supramolecular assemblies, novel hybrid materials, and large cross-linked or nonionizable polymers.
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Affiliation(s)
- Chrys Wesdemiotis
- Department of Chemistry, The University of Akron, Akron, OH, 44325, USA
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Wesdemiotis C. Mehrdimensionale Massenspektrometrie von synthetischen Polymeren und modernen Materialien. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201607003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Chrys Wesdemiotis
- Department of Chemistry; The University of Akron; Akron OH 44325 USA
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15
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Lai YH, Cai YH, Lee H, Ou YM, Hsiao CH, Tsao CW, Chang HT, Wang YS. Reducing Spatial Heterogeneity of MALDI Samples with Marangoni Flows During Sample Preparation. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2016; 27:1314-21. [PMID: 27126469 DOI: 10.1007/s13361-016-1406-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Revised: 04/02/2016] [Accepted: 04/05/2016] [Indexed: 05/20/2023]
Abstract
This work demonstrates a method to prepare homogeneous distributions of analytes to improve data reproducibility in matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Natural-air drying processes normally result in unwanted heterogeneous spatial distributions of analytes in MALDI crystals and make quantitative analysis difficult. This study demonstrates that inducing Marangoni flows within drying droplets can significantly reduce the heterogeneity problem. The Marangoni flows are accelerated by changing substrate temperatures to create temperature gradients across droplets. Such hydrodynamic flows are analyzed semi-empirically. Using imaging mass spectrometry, changes of heterogeneity of molecules with the change of substrate temperature during drying processes are demonstrated. The observed heterogeneities of the biomolecules reduce as predicted Marangoni velocities increase. In comparison to conventional methods, drying droplets on a 5 °C substrate while keeping the surroundings at ambient conditions typically reduces the heterogeneity of biomolecular ions by 65%-80%. The observation suggests that decreasing substrate temperature during droplet drying processes is a simple and effective means to reduce analyte heterogeneity for quantitative applications. Graphical Abstract ᅟ.
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Affiliation(s)
- Yin-Hung Lai
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China
| | - Yi-Hong Cai
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China
| | - Hsun Lee
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China
| | - Yu-Meng Ou
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China
- Chemistry Department, National Taiwan University, Taipei, 106, Taiwan, Republic of China
| | - Chih-Hao Hsiao
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China
| | - Chien-Wei Tsao
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China
- Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, Taipei, 106, Taiwan, Republic of China
| | - Huan-Tsung Chang
- Chemistry Department, National Taiwan University, Taipei, 106, Taiwan, Republic of China
| | - Yi-Sheng Wang
- Genomics Research Center, Academia Sinica, Taipei, 115, Taiwan, Republic of China.
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Kudina O, Eral B, Mugele F. e-MALDI: An Electrowetting-Enhanced Drop Drying Method for MALDI Mass Spectrometry. Anal Chem 2016; 88:4669-75. [PMID: 27026060 DOI: 10.1021/acs.analchem.5b04283] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The performance of matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) is frequently compromised by the heterogeneous distribution of matrix and analyte deposits on the target plate arising during the conventional drop-drying sample preparation procedure. It was recently shown that this so-called coffee stain effect can be suppressed by exciting evaporating complex fluids throughout the drying process using AC-electrowetting. Here, we demonstrate that electrowetting-assisted drying of solutions of common MALDI matrix materials and a variety of common low molecular weight pharmaceutical molecules indeed leads to substantially smaller and more homogeneous sample spots on special electrowetting-functionalized e-MALDI target plates. The improved spot quality enables 2-30× enhanced MALDI-MS signals along with substantial reductions of the typical lateral variations of the MALDI-MS. The latter largely eliminates the time-consuming need to search for "sweet spots".
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Affiliation(s)
- Olena Kudina
- Physics of Complex Fluids, MESA+ Institute for Nanotechnology, University of Twente , PO Box 217, 7500 AE Enschede, The Netherlands
| | - Burak Eral
- eMALDI BV , Hengelosestraat 511, 7521 AG Enschede, The Netherlands
| | - Frieder Mugele
- Physics of Complex Fluids, MESA+ Institute for Nanotechnology, University of Twente , PO Box 217, 7500 AE Enschede, The Netherlands.,eMALDI BV , Hengelosestraat 511, 7521 AG Enschede, The Netherlands
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17
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Abdelhamid HN. Ionic liquids for mass spectrometry: Matrices, separation and microextraction. Trends Analyt Chem 2016. [DOI: 10.1016/j.trac.2015.12.007] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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18
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Gabriel SJ, Steinhoff RF, Pabst M, Schwarzinger C, Zenobi R, Panne U, Weidner SM. Improved analysis of ultra-high molecular mass polystyrenes in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using DCTB matrix and caesium salts. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:1039-1046. [PMID: 26044271 DOI: 10.1002/rcm.7197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 03/09/2015] [Accepted: 03/09/2015] [Indexed: 06/04/2023]
Abstract
RATIONALE The ionization of polystyrenes in matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is typically achieved by the use of silver salts. Since silver salts can cause severe problems, such as cluster formation, fragmentation of polymer chains and end group cleavage, their substitution by alkali salts is highly desirable. METHODS The influence of various cations (Ag(+), Cs(+) and Rb(+)) on the MALDI process of polystyrene (PS) mixtures and high mass polystyrenes was examined. The sample preparation was kept as straightforward as possible. Consequently, no recrystallization or other cleaning procedures were applied. RESULTS The investigation of a polystyrene mixture showed that higher molecular polystyrenes could be more easily ionized using caesium, rather than rubidium or silver salts. In combination with the use of DCTB as matrix a high-mass polymer analysis could be achieved, which was demonstrated by the detection of a 1.1 MDa PS. CONCLUSIONS A fast, simple and robust MALDI sample preparation method for the analysis of ultra-high molecular weight polystyrenes based on the use of DCTB and caesium salts has been presented. The suitability of the presented method has been validated by using different mass spectrometers and detectors.
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Affiliation(s)
- S J Gabriel
- Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Strasse 11, 12489, Berlin, Germany
| | - R F Steinhoff
- Eidgenössisch Technische Hochschule Zürich, Department of Chemistry and Applied Biosciences, Vladimir Prelog Weg 3, 8093, Zürich, Switzerland
| | - M Pabst
- Eidgenössisch Technische Hochschule Zürich, Department of Chemistry and Applied Biosciences, Vladimir Prelog Weg 3, 8093, Zürich, Switzerland
| | - C Schwarzinger
- Johannes Kepler Universität Linz, Altenbergerstrasse 69, 4040, Linz, Austria
| | - R Zenobi
- Eidgenössisch Technische Hochschule Zürich, Department of Chemistry and Applied Biosciences, Vladimir Prelog Weg 3, 8093, Zürich, Switzerland
| | - U Panne
- Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Strasse 11, 12489, Berlin, Germany
- Humboldt-Universität zu Berlin, Department of Chemistry, Brook-Taylor-Str. 2, 12489, Berlin, Germany
| | - S M Weidner
- Federal Institute for Materials Research and Testing (BAM), Richard-Willstätter-Strasse 11, 12489, Berlin, Germany
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Chang HY, Huang MF, Hsu CL, Huang CC, Chang HT. Analyses of functional polymer-modified nanoparticles for protein sensing by surface-assisted laser desorption/ionization mass spectrometry coupled with HgTe nanomatrices. Colloids Surf B Biointerfaces 2015; 130:157-63. [DOI: 10.1016/j.colsurfb.2015.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Revised: 03/18/2015] [Accepted: 04/01/2015] [Indexed: 01/07/2023]
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Yoon D, Lee D, Lee JH, Cha S, Oh HB. Quantitative analysis of polyhexamethylene guanidine (PHMG) oligomers via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with an ionic-liquid matrix. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2015; 29:213-219. [PMID: 25641496 DOI: 10.1002/rcm.7096] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Revised: 11/09/2014] [Accepted: 11/10/2014] [Indexed: 06/04/2023]
Abstract
RATIONALE Quantifying polymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) with a conventional crystalline matrix generally suffers from poor sample-to-sample or shot-to-shot reproducibility. An ionic-liquid matrix has been demonstrated to mitigate these reproducibility issues by providing a homogeneous sample surface, which is useful for quantifying polymers. In the present study, we evaluated the use of an ionic liquid matrix, i.e., 1-methylimidazolium α-cyano-4-hydroxycinnamate (1-MeIm-CHCA), to quantify polyhexamethylene guanidine (PHMG) samples that impose a critical health hazard when inhaled in the form of droplets. METHODS MALDI-TOF mass spectra were acquired for PHMG oligomers using a variety of ionic-liquid matrices including 1-MeIm-CHCA. Calibration curves were constructed by plotting the sum of the PHMG oligomer peak areas versus PHMG sample concentration with a variety of peptide internal standards. RESULTS Compared with the conventional crystalline matrix, the 1-MeIm-CHCA ionic-liquid matrix had much better reproducibility (lower standard deviations). Furthermore, by using an internal peptide standard, good linear calibration plots could be obtained over a range of PMHG concentrations of at least 4 orders of magnitude. CONCLUSIONS This study successfully demonstrated that PHMG samples can be quantitatively characterized by MALDI-TOFMS with an ionic-liquid matrix and an internal standard.
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Affiliation(s)
- Donhee Yoon
- Department of Chemistry, Sogang University, Seoul, 121-742, Korea
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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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Gabriel SJ, Schwarzinger C, Schwarzinger B, Panne U, Weidner SM. Matrix segregation as the major cause for sample inhomogeneity in MALDI dried droplet spots. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2014; 25:1356-1363. [PMID: 24781460 DOI: 10.1007/s13361-014-0913-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 04/08/2014] [Accepted: 04/08/2014] [Indexed: 06/03/2023]
Abstract
The segregation in dried droplet MALDI sample spots was analyzed with regard to the matrix-to-sample ratio using optical microscopy, MALDI imaging mass spectrometry (MALDI MSI) and IR imaging spectroscopy. In this context, different polymer/matrix/solvent systems usually applied in the analysis of synthetic polymers were investigated. The use of typical matrix concentrations (10 mg mL⁻¹) in almost every case resulted in ring patterns, whereas higher concentrated matrix solutions always led to homogeneous sample spot layers. The data revealed that segregation is predominantly caused by matrix transport in the drying droplet, whereas polymer segregation seems to be only secondary.
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Affiliation(s)
- Stefan J Gabriel
- Federal Institute for Materials Research and Testing (BAM), D-12489, Berlin, Germany
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Bierstedt A, Stindt A, Warschat C, Panne U, Riedel J. High repetition rate atmospheric pressure matrix-assisted laser desorption/ionization in combination with liquid matrices. EUROPEAN JOURNAL OF MASS SPECTROMETRY (CHICHESTER, ENGLAND) 2014; 20:367-374. [PMID: 25707126 DOI: 10.1255/ejms.1292] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
One major drawback of matrix-assisted laser desorption/ionization (MALDI) is still the relatively poor pulse-to-pulse reproducibility of the signal intensity. This problem, caused by insufficient homogeneity in the matrix/analyte co-crystallization, is usually circumvented by averaging the detected ion intensity over several shots. However, during the consecutive laser pulses, the applied matrix gets depleted and only a number of subsequent experiments can be done on the same sample spot. In order to achieve the desired long-term stability in combination with a sufficient pulse-to-pulse reproducibility, recently liquid MALDI matrices have been introduced. This contribution demonstrates the promising combination of liquid matrices with high repetition rate lasers for atmospheric pressure MALDI (AP-MALDI). To demonstrate the robustness of the new approach, two different kinds of liquid matrices were used in combination with both a typical flashlamp pumped 15 Hz laser and a diode pumped solid state laser operated at 5 kHz. The latter showed a stable ion signal over more than 3,500,000 consecutive laser pulses.
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