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

Trimpin, Sarah; Keune, S.; Räder, Hans Joachim; Müllen, Kläus

doi:10.1016/j.jasms.2006.01.007

Cited by 108 publications

(165 citation statements)

References 33 publications

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“…In practice, during the MALDI experiment, the necessary components of the experiment (analyte, matrix, and cationization agent) are all plentiful and available within the area of the laser spot on the target. The absence of solvent may aid these experiments by eliminating the crystallization effects that impart heterogeneous morphology to some solventbased MALDI samples [14]. Now that we observe the high degree of homogeneity in these samples, the key question is how 60 s of vortexing and a simple spatula transfer can create such a homogeneous thin film for the MALDI experiment to interrogate?…”

Section: Resultsmentioning

confidence: 98%

“…To address these issues, solvent-free sample preparation methods have been developed. While several groups investigated solventfree sample preparation methods at nearly the same time, the methods developed by Trimpin, Räder, and coworkers have gained widespread use [11][12][13][14][15]. To make the sample preparation step easier, less time consuming, and reduce the risk of cross-contamination, we developed a simple version of the solvent-free sample preparation method, now called the vortex method [16].…”

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confidence: 99%

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Imaging the morphology of solvent-free prepared MALDI samples

Hanton

McEvoy

Stets

2008

J. Am. Soc. Mass Spectrom.

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Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry is an important technique to characterize many different materials, including synthetic polymers. MALDI mass spectral data can be used to determine the polymer average molecular weights, repeat units, and end groups. The development of solvent-free sample preparation methods has enabled MALDI to analyze insoluble materials and, interestingly, can provide higher-quality mass spectral data. Although the utility of solvent-free sample preparation for MALDI has been demonstrated, the reasons for its success are only now being discovered. In this study, we use microscopy tools to image samples prepared using solvent-free methods to examine the morphology of these samples. The samples are prepared using a simple vortex method. Our results show that the average particle size of typical MALDI matrices is reduced from their original tens to hundreds of micrometers to hundreds of nanometers. This size reduction of the matrix occurs in one minute using the vortex method. We also observe remarkably smooth and homogeneous sample morphologies for the laser to interrogate, especially considering the relatively crude methods used to prepare our samples. [5][6][7][8][9][10]. MALDI can generate important data on the telomer repeat units, end groups, and average molecular weights of these materials. MALDI methods have been developed to address a broad variety of different polymer materials containing different chemistries. One of the key issues in traditional MALDI sample preparation is making true solutions of the analyte and the matrix [9]. Many interesting polymeric analytes are either completely insoluble or present significant challenges in making analytically useful solutions. To address these issues, solvent-free sample preparation methods have been developed. While several groups investigated solventfree sample preparation methods at nearly the same time, the methods developed by Trimpin, Räder, and coworkers have gained widespread use [11][12][13][14][15]. To make the sample preparation step easier, less time consuming, and reduce the risk of cross-contamination, we developed a simple version of the solvent-free sample preparation method, now called the vortex method [16]. Although the utility of solvent-free sample preparation for MALDI has been clearly demonstrated, the investigations into why it works and what impact these data have on our overall understanding of the MALDI process have only recently begun [17,18].To develop increased understanding of the utility of the solvent-free MALDI sample preparation method, we have investigated the morphology of these samples using different imaging experiments-optical imaging [19], scanning electron microscopy (SEM) [20], atomic force microscopy (AFM) [21], and time-of-flight secondary ion mass spectrometry (ToF-SIMS) [22]. Previous work has shown the utility of investigating MALDI sample morphology using imaging methods. We have used SEM to investigate the morphology of electrospray deposited samples [23] ...

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Section: Resultsmentioning

confidence: 98%

mentioning

confidence: 99%

Imaging the morphology of solvent-free prepared MALDI samples

Hanton

McEvoy

Stets

2008

J. Am. Soc. Mass Spectrom.

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“…No limits on the molecular weight (MW) of the analyte [5], the solubility [3,6,7] or the compatibility between the polarities of analyte and matrix [7] have been reported. The ball mill procedure [5,7] exhibited excellent homogeneity and better efficiency as a result of automatic pulverization and mixing. Three different approaches for avoiding solvent in the sample preparation seem to vary in methodology only slightly, but differences in the resulting data can be significant.…”

mentioning

confidence: 99%

“…Advantages are that the analyte segregation phenomena are overcome, the method is facile and reduces the time-consuming optimization of the threecomponent matrix/solvent/analyte system, fewer sample/matrix combinations need to be considered, fewer problems arising from trace impurities from binary solvents are produced, it is more universal since insoluble analytes are accessible, and the reliability is greater since suppression effects are reduced [6,7,10]. The potential for quantitation, high throughput, and automation of MALDI-MS is also enhanced [7]. Only a few reports [4, 5, 10 -13] describe solvent-free MALDI-MS for the analysis of proteins and peptides.…”

mentioning

confidence: 99%

“…It was shown that this MALDI method permits a true matrix-assistance [5]. No limits on the molecular weight (MW) of the analyte [5], the solubility [3,6,7] or the compatibility between the polarities of analyte and matrix [7] have been reported. The ball mill procedure [5,7] exhibited excellent homogeneity and better efficiency as a result of automatic pulverization and mixing.…”

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Solvent-free MALDI-MS for the analysis of biological samples via a mini-ball mill approach

Trimpin

Deinzer

2005

J. Am. Soc. Mass Spectrom.

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An efficient, low sample load mini-ball mill (MBM) sample preparation procedure was developed for solvent-free MALDI analysis of peptides and proteins. Picomole sample amounts can be handled conveniently, with 30 s grinding times being sufficient. Matrix purity and molar analyte/matrix ratios are not as critical as with methods employing solvent. Ammonium salt is employed for protonation of the peptide and suppression of sodiation. This strategy allows for peptide mapping and other biochemical manipulations to be performed prior to MBM sample preparation and mass analysis. The analysis of bovine serum albumin (66 kDa) yielded good results, indicating that higher molecular weight proteins are accessible. A semi-solvent-free strategy by the MBM sample preparation method is also described. ( The procedure is generally referred to as "solvent-free MALDI-MS". It was shown that this MALDI method permits a true matrix-assistance [5]. No limits on the molecular weight (MW) of the analyte [5], the solubility [3,6,7] or the compatibility between the polarities of analyte and matrix [7] have been reported. The ball mill procedure [5,7] exhibited excellent homogeneity and better efficiency as a result of automatic pulverization and mixing. Three different approaches for avoiding solvent in the sample preparation seem to vary in methodology only slightly, but differences in the resulting data can be significant. Solvent-free MALDI-MS is believed to be the most promising approach [8,9]. Surprisingly, solvent-free MALDI-MS often yields better spectra than solvent-based MALDI-MS, particularly for synthetic polymers, and it typically requires less laser power for successful analysis of the analyte [5,7]. Advantages are that the analyte segregation phenomena are overcome, the method is facile and reduces the time-consuming optimization of the threecomponent matrix/solvent/analyte system, fewer sample/matrix combinations need to be considered, fewer problems arising from trace impurities from binary solvents are produced, it is more universal since insoluble analytes are accessible, and the reliability is greater since suppression effects are reduced [6,7,10]. The potential for quantitation, high throughput, and automation of MALDI-MS is also enhanced [7]. Only a few reports [4, 5, 10 -13] describe solvent-free MALDI-MS for the analysis of proteins and peptides. In this study, we developed a universal mini-ball mill (MBM) method to prepare biological target samples for solvent-free MALDI-MS.

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Mass Spectrometry

Guttman¹

2010

Encyclopedia of Polymer Science and Technology

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We describe various forms of matrix‐assisted laser desorption/ionization (MALDI) in the determination of the molecular mass distribution (MMD) and the polymer architecture. The time‐o‐flight (TOF) mass spectrometry (MS) system is described in detail this system is the most common in use today for MALDI analysis of synthetic polymers. Because sample preparation poses the major problem in obtaining and analyzing spectra using the TOF/MS methods, we offer detailed descriptions of these methods including those needed to calibrate the mass axis and the signal axis. We also review a variety of applications of MALDI to synthetic polymers such as MMD, molecular composition distribution (MCD) of copolymers, polymer architecture, combinations of MALDI TOF MS with size exclusion chromatography and other forms of polymer chromatography, as well as the use of MALDI in elucidating polymer chemical reactions mechanisms.

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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

Cited by 108 publications

References 33 publications

Imaging the morphology of solvent-free prepared MALDI samples

Imaging the morphology of solvent-free prepared MALDI samples

Solvent-free MALDI-MS for the analysis of biological samples via a mini-ball mill approach

Mass Spectrometry

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