Matrix/sample interactions in ultraviolet laser‐desorption of proteins

Doktycz, Stephen J.; Savickas, Philip J.; Krueger, Duane A.

doi:10.1002/rcm.1290050402

Cited by 52 publications

(39 citation statements)

References 10 publications

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“…The common understanding of the matrix assistance in MALDI-MS assumes a preorganized system where the analyte is homogeneously embedded in a matrix, allowing a "soft" desorption/ionization process [5,6]. Hence, in MALDI-MS, sample preparation is one of the key factors that greatly influence the success and the quality of the mass spectrometric analysis.…”

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confidence: 99%

“…(J Am Soc Mass Spectrom 2006, 17, 661-671) M atrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been extensively applied to the characterization of soluble macromolecules [1, 2] and has even been used to detect intact soluble molecules with masses higher than one million Da [3,4]. The common understanding of the matrix assistance in MALDI-MS assumes a preorganized system where the analyte is homogeneously embedded in a matrix, allowing a "soft" desorption/ionization process [5,6]. Hence, in MALDI-MS, sample preparation is one of the key factors that greatly influence the success and the quality of the mass spectrometric analysis.…”

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confidence: 99%

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Solvent-free MALDI-MS: Developmental improvements in the reliability and the potential of MALDI in the analysis of synthetic polymers and giant organic molecules

Trimpin¹,

Keune²,

Räder

et al. 2006

J. Am. Soc. Mass Spectrom.

108

161

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A dry sample preparation strategy was previously established as a new method for matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS), so-called solvent-free MALDI-MS. In this contribution, we examine systems that have been shown problematic with conventional solvent-based MALDI approaches. Problems frequently encountered are solubility, miscibility, and segregation effects during crystallization as a result of unfavorable analyte and matrix polarities. In all cases studied, solvent-free MALDI-MS simplified the measurement and improved the analysis. Solvent-free MALDI-MS enables more reliable results in well-known problematic systems such as polydimethylsiloxane with its segregation effects. However, even in highly compatible analyte/matrix systems such as polystyrene and dithranol, there were undesirable suppression effects when employing THF as solvent. Generally, the solvent-free method allows for more homogeneous analyte/matrix mixtures as well as higher shot-to-shot and sample-to-sample reproducibility. As a result, less laser power has to be applied, which yields milder MALDI conditions, reduced background signals, and provides better resolution of the analyte signals. Solvent-free MALDI-MS proved valuable for the characterization of nanosized material, e.g., fullereno-based structures, which indicated having an increased fragmentation-susceptibility. New analyte/matrix combinations (e.g., polyvinylpyrrolidone/dithranol) are accessible independent of solubility and compatibility in common solvents. An improved quantitation potential is recognized (e.g., insoluble polycyclic aromatic hydrocarbon against soluble dendrite precursor). The rapid and easy measurement of industrial products demonstrates the solvent-free method capable for improved throughput analysis of a variety of compounds (e.g., poly(butylmethacrylate) diol) in routine industrial analysis. Hence, this new MALDI method leads to qualitative and quantitative improvements, making it a powerful tool for analytical purposes, which may also prove to be valuable in future automation attempts.

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confidence: 99%

mentioning

confidence: 99%

Solvent-free MALDI-MS: Developmental improvements in the reliability and the potential of MALDI in the analysis of synthetic polymers and giant organic molecules

Trimpin¹,

Keune²,

Räder

et al. 2006

J. Am. Soc. Mass Spectrom.

108

161

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“…To investigate the MALDI process, many studies have focused on sample morphology using different imaging experiments. Sample heterogeneity and distribution of molecules within the MALDI solid sample have been explored using microscopy techniques, such as optical microscopy [6,7], scanning electron microscopy [8 -12], atomic force microscopy [12], and confocal laser scanning microscopy [13,14]. Spectroscopic techniques, such as fluorescence spectrophotometry [13] or Raman spectrometry [8] were also implemented in conjunction with microscopy to obtain complementary information.…”

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confidence: 99%

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

Pizzala

Barrère

Mazarin

et al. 2009

J. Am. Soc. Mass Spectrom.

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Solid-state Nuclear magnetic resonance (NMR) was used here to explore structural characteristics of samples to be subjected to matrix-assisted laser desorption/ionization (MALDI) and prepared without the use of any solvent. The analytical systems scrutinized in NMR were mixtures of a 2,5-dihydroxybenzoic acid (2,5-DHB) matrix and caesium fluoride (CsF), used as the cationization agent in synthetic polymer MALDI mass analysis, at different molar ratios (1:1, 5:1, and 10:1). Complementary information could be obtained from 13 C, 133 Cs, and 19 F NMR spectra. Grinding the matrix together with the salt in the solid state was shown to induce a strong modification in the molecular organization within the MALDI sample. The evidenced mechano-induced reactions allow strong interactions between the matrix and the cation, up to the formation of a salt, and only occur in the presence of some water molecules. Addition of a poly(ethylene oxide) polymer as the analyte did not further modify the observed molecular organizations. Although relative matrix and salt concentrations in the scrutinized samples were unusual for MALDI analysis, mass spectra of good quality could be obtained and revealed that cation attachment on polymers during the MALDI process is not a matrix-independent event since a lower ionization efficiency was obtained from highly organized solid samples, mostly consisting of 2,5-DHB caesium salt species. (J Am Soc Mass Spectrom 2009, 20, 1906 -1911) © 2009 American Society for Mass Spectrometry M atrix-assisted laser desorption/ionization (MALDI) is widely used as an efficient ionization method to characterize synthetic polymers by time-of-flight mass spectrometry (TOF MS) [1,2]. A key point in the success of a MALDI-MS analysis is sample preparation, that is, proper matrix and cation selection as well as solid-state organization. The matrix actually plays multiple roles in the MALDI process and should accordingly present specific properties. Some criteria are clearly defined, such as a strong absorptivity at the employed laser wavelength or good vacuum stability, while other requirements, such as a good miscibility of the matrix with the analyte in the solid state, are not easily related to physico-chemical parameters of the matrix. As a result, prediction for the optimal matrix-polymer system is still not possible and sample preparation methods are usually developed from published protocols that were shown to work for a given polymeric system [3]. In particular, solvent-free MALDI was recently proposed as an alternative to the conventional dried droplet method [4,5].Despite MALDI being a widely used technique, mechanisms underlying this desorption/ionization process are still not fully understood. To investigate the MALDI process, many studies have focused on sample morphology using different imaging experiments. Sample heterogeneity and distribution of molecules within the MALDI solid sample have been explored using microscopy techniques, such as optical microscopy [6,7], scanning electron microscopy [8 -...

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“…Hence, MALDI‐MS is considered as a very ‘soft’ desorption/ionization process in mass spectrometry 7,. 8 It is assumed that this ‘soft’ process is due to preorganized crystal formation, where the analyte is built in the matrix crystal during solvent evaporation, enabling a proper matrix assistance during the desorption step 9,. 10 Evidently, one of the key factors that greatly influences the success and the quality of MALDI mass spectrometric analysis is the sample preparation step.…”

mentioning

confidence: 99%

New aspects in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry: a universal solvent‐free sample preparation

Trimpin

Rouhanipour

et al. 2001

Rapid Comm Mass Spectrometry

178

231

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A method of solvent-free sample preparation is shown to be of universal applicability for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Results obtained were compared with those of traditional solvent-based sample preparation for MALDI-MS in order to demonstrate their similarities with respect to accuracy, sensitivity and resolution for polymers such as polystyrene and poly(methyl methacrylate) in a mass range from 2 to 100 kDa. The results revealed that there is fundamentally no difference in the quality of the obtained mass spectra, and we conclude that the mechanism of desorption and ionization remains unchanged. However, the solvent-free sample preparation turned out to have some advantages over the traditional method in certain cases: quick and easy applicability is shown for polyetherimide avoiding time-consuming optimization procedures. In particular, industrial pigments that are insoluble in common solvents were characterized without interfering signals from fragments. The method even showed improvements with respect to reproducibility and mass discrimination effects in comparison to traditional sample preparation. Additionally, this contribution provides new insight regarding the analyte/matrix preorganization for the desorption step which now appears to be independent of crystallinity.

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Matrix/sample interactions in ultraviolet laser‐desorption of proteins

Cited by 52 publications

References 10 publications

Solvent-free MALDI-MS: Developmental improvements in the reliability and the potential of MALDI in the analysis of synthetic polymers and giant organic molecules

Solvent-free MALDI-MS: Developmental improvements in the reliability and the potential of MALDI in the analysis of synthetic polymers and giant organic molecules

Solid state nuclear magnetic resonance as a tool to explore solvent-free MALDI samples

New aspects in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry: a universal solvent‐free sample preparation

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