Electrophilic properties of common MALDI matrix molecules

Lippa, T. P.; Eustis, Soren N.; Wang, D.; Bowen, Kit H.

doi:10.1016/j.ijms.2007.07.019

Cited by 10 publications

(7 citation statements)

References 29 publications

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“…Acid–base neutralization followed by photoionization of neutralized matrix molecules seems to be unlikely due to the unfavorable irradiation parameters. Lippa et al observed photoelectron detachment from a multitude of matrix anions with vertical detachment energies of about 1 eV, which can be easily provided at irradiation wavelengths of 337 and 355 nm with photon energies of 3.68 and 3.49 eV, respectively . The energy of electrons generated in MALDI was estimated to be ≤2 eV, which is well below the threshold of 15 eV up to which low-energy capture of neutral matrices leads to formation of matrix anions .…”

Section: Resultsmentioning

confidence: 99%

“…Lippa et al observed photoelectron detachment from a multitude of matrix anions with vertical detachment energies of about 1 eV, which can be easily provided at irradiation wavelengths of 337 and 355 nm with photon energies of 3.68 and 3.49 eV, respectively. 17 The energy of electrons generated in MALDI was estimated to be ≤2 eV, 18 which is well below the threshold of 15 eV up to which low-energy capture of neutral matrices leads to formation of matrix anions. 19 Consequently, electron capture of positively precharged matrix bases in ion crystals of LSMs are most likely.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Enhanced MALDI MS Sensitivity by Weak Base Additives and Glycerol Sample Coating

2013

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The concept of rationally designing MALDI matrices has been extended to the next "whole sample" level. These studies have revealed some unexpected and exploitable insights in improving MALDI sensitivity. It is shown that (i) additives which only provide additional laser energy absorption are best to be avoided; (ii) the addition of proton donors in the form of protonated weak bases can be highly beneficial; (iii) the addition of glycerol for coating crystalline samples is highly recommended. Overall, analytical sensitivity has been significantly increased compared to the current "gold" standards in MALDI MS, and new insights into the mechanisms and processes of MALDI have been gained.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Enhanced MALDI MS Sensitivity by Weak Base Additives and Glycerol Sample Coating

2013

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“…Electron affinities for seven common MALDI matrices have been published (Lippa et al, 2007) but, although the information will be valuable for development of models of the MALDI process, the authors point out that equivalent data for the analyte molecules is also necessary. Potassium cation affinities of benzoic acid derivatives have been determined by threshold collision-induced dissociation (Chinthaka & Rodgers, 2007).…”

Section: Theorymentioning

confidence: 99%

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2007–2008

Harvey

2011

Mass Spectrometry Reviews

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This review is the fifth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2008. The first section of the review covers fundamental studies, fragmentation of carbohydrate ions, use of derivatives and new software developments for analysis of carbohydrate spectra. Among newer areas of method development are glycan arrays, MALDI imaging and the use of ion mobility spectrometry. The second section of the review discusses applications of MALDI MS to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, biopharmaceuticals, glycated proteins, glycolipids, glycosides and various other natural products. There is a short section on the use of MALDI mass spectrometry for the study of enzymes involved in glycan processing and a section on the use of MALDI MS to monitor products of the chemical synthesis of carbohydrates with emphasis on carbohydrate-protein complexes and glycodendrimers. Corresponding analyses by electrospray ionization now appear to outnumber those performed by MALDI and the amount of literature makes a comprehensive review on this technique impractical. However, most of the work relating to sample preparation and glycan synthesis is equally relevant to electrospray and, consequently, those proposing analyses by electrospray should also find material in this review of interest.

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“…Variations of experimentally accessible parameters such as, e.g., laser fluence and irradiation wavelength as well as matrix and analyte properties led to a large variety of proposals and partial aspects regarding the underlying processes [2,. For closer insights, the physicochemical reactions taking place were elucidated by determination of the gas phase basicities as well as proton and electron affinities of the involved matrix [29][30][31][32][33][34][35][36] and analyte [37][38][39][40][41][42][43] neutral and ion species and were complemented by theoretical considerations and computational chemistry [34,[44][45][46][47][48][49]. From these investigations, two conflicting theories predominantly discussed nowadays emerged: The Lucky Survivor theory [17,50] and the gas phase protonation model [5,16,24,28,51].…”

Section: Introductionmentioning

confidence: 99%

Compelling Evidence for Lucky Survivor and Gas Phase Protonation: The Unified MALDI Analyte Protonation Mechanism

Jaskolla

Karas

2011

J. Am. Soc. Mass Spectrom.

166

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This work experimentally verifies and proves the two long since postulated matrix-assisted laser desorption/ionization (MALDI) analyte protonation pathways known as the Lucky Survivor and the gas phase protonation model. Experimental differentiation between the predicted mechanisms becomes possible by the use of deuterated matrix esters as MALDI matrices, which are stable under typical sample preparation conditions and generate deuteronated reagent ions, including the deuterated and deuteronated free matrix acid, only upon laser irradiation in the MALDI process. While the generation of deuteronated analyte ions proves the gas phase protonation model, the detection of protonated analytes by application of deuterated matrix compounds without acidic hydrogens proves the survival of analytes precharged from solution in accordance with the predictions from the Lucky Survivor model. The observed ratio of the two analyte ionization processes depends on the applied experimental parameters as well as the nature of analyte and matrix. Increasing laser fluences and lower matrix proton affinities favor gas phase protonation, whereas more quantitative analyte protonation in solution and intramolecular ion stabilization leads to more Lucky Survivors. The presented results allow for a deeper understanding of the fundamental processes causing analyte ionization in MALDI and may alleviate future efforts for increasing the analyte ion yield.

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Electrophilic properties of common MALDI matrix molecules

Cited by 10 publications

References 29 publications

Enhanced MALDI MS Sensitivity by Weak Base Additives and Glycerol Sample Coating

Enhanced MALDI MS Sensitivity by Weak Base Additives and Glycerol Sample Coating

Analysis of carbohydrates and glycoconjugates by matrix‐assisted laser desorption/ionization mass spectrometry: An update for 2007–2008

Compelling Evidence for Lucky Survivor and Gas Phase Protonation: The Unified MALDI Analyte Protonation Mechanism

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