Sample Preparation: A Crucial Factor for the Analytical Performance of Rationally Designed MALDI Matrices

Wiangnon, Kanjana; Cramer, Rainer

doi:10.1021/ac504412p

Cited by 24 publications

(18 citation statements)

References 15 publications

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“…Several studies compared the effects of matrix application techniques on several aspects of MALDI‐MSI performance, including analyte diffusion, reproducibility, and sensitivity that are directly related to the ISE of a MALDI source . MALDI sensitivity was also reported to be improved through the rational design of matrices and the addition of glycerol which generates multiply charged protein/peptide ions . Multiply charged ions can also be produced with matrix and vacuum alone without the use of a laser, with a reflective geometry, or with a laser in a transmission geometry .…”

Section: Introductionmentioning

confidence: 99%

Characterizing and alleviating ion suppression effects in atmospheric pressure matrix‐assisted laser desorption/ionization

Cao

Liu

et al. 2019

Rapid Comm Mass Spectrometry

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RATIONALE: As a powerful ambient ion source, atmospheric pressure (AP)-MALDI enables direct analysis at atmospheric pressure/temperature and minimal sample preparation. With the increasing usage of AP-MALDI sources with Orbitrap instruments, systematic characterization of the extent of ion suppression effect (ISE) in AP-MALDI-Orbitrap mass spectrometry imaging (MSI) is desirable. Recently, a new low-pressure MALDI platform has been introduced that reportedly provided better sensitivity. While extensive research efforts have been devoted to improving spatial resolution, fewer studies focused on the characterization and sensitivity improvement of these MALDI platforms that, coupled with high-resolution Orbitraps, provide powerful strategy for MS imaging. METHODS: Here, we compared the analytical performance of AP and low-pressure (subatmospheric) MALDI sources to study the effect of pressure control in the ion source. Using a model peptide/protein mixture, we systematically evaluated the factors influencing ISE. Furthermore, the effect of laser spot size was evaluated through tissue imaging analysis of lipids and neuropeptides. The effects of ion suppression and laser spot size have also been examined by comparing the number of identified molecular species during MSI analysis. RESULTS: Several key operating parameters including source pressure, laser energy, laser repetition rate, and microscopic slide coating materials were optimized to minimize the ISE. Under the optimal conditions, the subatmospheric AP-MALDI-Orbitrap platform with high spatial and mass spectral resolution enabled significantly improved coverage of several lipid and neuropeptide families in the MS analysis of mouse brain tissue sections. CONCLUSIONS: The new SubAP-MALDI source coupled with an Orbitrap mass spectrometer was established as a viable platform for in situ endogenous biomolecular analysis with increased sensitivity compared to conventional AP-MALDI sources as evidenced by the confident identification of neuropeptides from mouse brain imaging analyses. The alleviated ISE was key to substantial performance improvement due to optimized intermediate pressure conditions and better ion collection by the ion funnel.

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Section: Introductionmentioning

confidence: 99%

Characterizing and alleviating ion suppression effects in atmospheric pressure matrix‐assisted laser desorption/ionization

Cao

Liu

et al. 2019

Rapid Comm Mass Spectrometry

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“…It can be caused by the competitive desorption and/or ionization between co‐existing components. The outcome of the competition is affected by many factors including the choice of matrix, the physicochemical properties of the analytes, the sample preparation method and the solvent and pH value of the MALDI solution . It can be envisaged that a bigger difference in desorption/ionization between analytes will lead to a stronger ASE.…”

Section: Introductionmentioning

confidence: 99%

“…The outcome of the competition is affected by many factors including the choice of matrix, the physicochemical properties of the analytes, the sample preparation method and the solvent and pH value of the MALDI solution. [14][15][16][17] It can be envisaged that a bigger difference in desorption/ionization between analytes will lead to a stronger ASE. In order to reduce the ASE, therefore, methods should be designed to weaken the competition for desorption and ionization.…”

Section: Introductionmentioning

confidence: 99%

A sample preparation method for recovering suppressed analyte ions in MALDI TOF MS

et al. 2015

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In matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS), analyte signals can be substantially suppressed by other compounds in the sample. In this technical note, we describe a modified thin-layer sample preparation method that significantly reduces the analyte suppression effect (ASE). In our method, analytes are deposited on top of the surface of matrix preloaded on the MALDI plate. To prevent embedding of analyte into the matrix crystals, the sample solution were prepared without matrix and efforts were taken not to re-dissolve the preloaded matrix. The results with model mixtures of peptides, synthetic polymers and lipids show that detection of analyte ions, which were completely suppressed using the conventional dried-droplet method, could be effectively recovered by using our method. Our findings suggest that the incorporation of analytes in the matrix crystals has an important contributory effect on ASE. By reducing ASE, our method should be useful for the direct MALDI MS analysis of multicomponent mixtures.

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“…Overall, the results obtained by using monoaromatic lichen metabolites as matrices were quite close to those of DHB. At this point it should be mentioned that DHB is reported a suitable matrix for the ionization of peptides, but it failed to do so in the present experiments. This observation is most reasonably explained by the fact that due to the large number of tested matrices, the experimental conditions had to be very general and could not be adapted to the specific requirements of DHB.…”

Section: Resultsmentioning

confidence: 58%

The inherent matrix properties of lichen metabolites in matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry

Pogam

Boustié

Richomme

et al. 2017

Rapid Comm Mass Spectrometry

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Lichen metabolites exhibit interesting MALDI matrix properties, especially for medium and low molecular weight analytes. For many of the tested molecules, matrix ion formation was very limited. This proof-of-concept study paves the way for follow-up investigations to assess the matrix properties of lichen metabolites against a wider array of analytes as well as adapting experimental settings to individually optimize the performance of successfully tested candidates.

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Sample Preparation: A Crucial Factor for the Analytical Performance of Rationally Designed MALDI Matrices

Cited by 24 publications

References 15 publications

Characterizing and alleviating ion suppression effects in atmospheric pressure matrix‐assisted laser desorption/ionization

Characterizing and alleviating ion suppression effects in atmospheric pressure matrix‐assisted laser desorption/ionization

A sample preparation method for recovering suppressed analyte ions in MALDI TOF MS

The inherent matrix properties of lichen metabolites in matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry

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