On the mechanism and control of salt-induced resolution loss in matrix-assisted laser desorption/ionization

Dubois, Frédéric; Knochenmuss, Richard; Steenvoorden, R.J.J.M.; Breuker, Kathrin; Zenobi, Renato

doi:10.1255/ejms.68

Cited by 24 publications

(14 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The excess positive charge of Co 2 + in the cluster series marked with stars and circles are compensated by deprotonation of a corresponding number of DHB molecules. These observations agree with the results of Dubois et al 19 They found an analogous repeat unit as well as deprotonation of DHB in clusters formed with Ca 2 + . The observed mechanism of charge compensation is also consistent with the complexation behavior of DHB.…”

Section: Resultssupporting

confidence: 93%

“…All the mass spectra shown were recorded in positive ion mode. A more detailed description of the apparatus can be found in the paper of Dubois et al 19 High resolution mass spectrometry. For one test experiment, a mass resolution exceeding the one of our TOF instrument was needed.…”

Section: Spectroscopic Measurementsmentioning

confidence: 99%

“…An approach with coordination chemistry as the basis for cationization in MALDI has never been undertaken before, although it is known that MALDI matrices form metal ion mediated adducts with certain analytes, often resulting in degraded mass resolution and accuracy. 19 As the complexing ability of matrices has not been studied systematically, we first investigated the question of preformed ions by studying matrix complexes.The following chemical systems were investigated:Ni 2 + and Co 2 + were chosen as coordination centers because transition metal ions are potential MALDI cationizing agents. O-phenanthroline (ophen) and 2,2'-bipyridine (bpy) are models for heteroaromatic (bio-)molecules and served as bidentate nitrogen ligands for the transition metal ions, forming the octahedral complexes [Co(bpy) 3 ]Cl 2 and [Ni(ophen) 3 ]Cl 2 .…”

mentioning

confidence: 99%

See 2 more Smart Citations

Ionization mechanisms in matrix-assisted laser desorption/ionization mass spectrometry: contribution of pre-formed ions

Lehmann

Knochenmuss

Zenobi

1997

Rapid Commun. Mass Spectrom.

Self Cite

View full text Add to dashboard Cite

The mechanisms of ion formation in matrix-assisted laser desorption/ionization mass spectrometry are still largely unknown. Ions may exist as pre-formed species in the solid state, or may form by ion-molecule reactions initiated by the laser shot, or, most probably, they may originate from a combination of both processes. The contribution of pre-formed ions was approached from the standpoint of coordination chemistry and studied in different transition metal ion/matrix systems as well as in the copper/polystyrene system. The solution, the solid and the gas phases were investigated by means of infrared, visible and proton nuclear magnetic resonance spectroscopy, as well as by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. It was found that the contribution of pre-formed ions can be predicted on the basis of condensed phase thermodynamics. MALDI mass spectra qualitatively reflect the amount of pre-formed complexes in the solid target. © 1997 by John Wiley & Sons, Ltd. Received 25 May 1997; Revised 28 July 1997; Accepted 28 July 1997 Rapid. Commun. Mass Spectrom. 11, 1483-1492 Since its introduction in 1988, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has developed into a powerful tool for the analysis of biomolecules and synthetic polymers.1-8 However, the mechanisms of ion formation are still not fully understood. Two main possibilities exist: ions may either exist 'pre-formed' in the solid state and simply be liberated upon laser irradiation, or they may form by ion-molecule reactions initiated by the laser pulse. Until now, studies have focused on post-desorption reactions.9-13 Only a few experimental studies on preformed ions have been performed. Liao and Allison 14 found that, under the conditions of their experiment, peptides which had been derivatized with a charged triphenylphosphonium group yielded a signal. This was not the case for underivatized peptides. The authors attributed this to the fact that derivatized peptides are already ionized in the solid and only have to be desorbed, which decreases the laser energy requirement. Nelson and Hutchens 15 performed cationization experiments with a histidine-rich peptide and reported results suggesting pre-formed ions. After washing a sample containing matrix, peptide and metal salt, copper-peptide adducts were still observed in the MALDI spectra, whereas sodium and potassium adducts disappeared. This observation was attributed to the fact that the copper adducts are pre-formed in solution, but not the sodium and potassium adducts.For the cationization of other analytes such as apolar polymers which are preferentially cationized with transition metal ions in MALDI, it is widely assumed that cation attachment takes place in the gas phase. [16][17][18] However, little experimental evidence exists to support this statement.The purpose of this study was to investigate the contribution of pre-formed ions to the ion signal observed in MALDI. We were especially interested in predicting this contribution based on p...

show abstract

Section: Resultssupporting

confidence: 93%

Section: Spectroscopic Measurementsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Ionization mechanisms in matrix-assisted laser desorption/ionization mass spectrometry: contribution of pre-formed ions

Lehmann

Knochenmuss

Zenobi

1997

Rapid Commun. Mass Spectrom.

Self Cite

View full text Add to dashboard Cite

show abstract

“…59 Certain metals seem to favor this pathway, particularly as complex adducts with deprotonated matrix. 2,49,51,59 Matrix probably acts as a bidentate ligand in many cases. 50 Delocalized multiply protonated ions.…”

Section: 34mentioning

confidence: 99%

Secondary ion-molecule reactions in matrix-assisted laser desorption/ionization

et al. 2000

View full text Add to dashboard Cite

Ion-molecule charge- and proton-transfer reactions in the desorption plume are considered for the case of matrix-assisted laser desorption/ionization (MALDI) with ultraviolet laser excitation, and it is proposed that they are major determinants of the observed mass spectrum. Specific MALDI phenomena which are discussed include the dominance of singly charged ions and analyte-matrix or analyte-analyte signal suppression. Should any be formed, highly charged products can be reduced by reaction with neutral matrix, yet singly charged ions cannot generally be neutralized in the same manner. Ion suppression effects can also be explained by similar reactions, which in some cases involve interconversion of dissimilar ion types. The plume is proposed often to be more under thermodynamic rather than kinetic control owing to these secondary reactions. UV/MALDI mass spectra should therefore be largely predictable, given sufficient thermodynamic information, and appropriate experimental conditions of sufficient analyte and plume density. Copyright 2000 John Wiley & Sons, Ltd.

show abstract

“…During laser irradiation, these nonspeciÐc complexes are simply desorbed from the condensed phase.17 A combination of desorption of preformed ions with subsequent gasphase cationization thus seems to be a general phenomena in the ion formation in MALDI mass spectrometry. 17,22,23 An excess of metal ions in the MALDI sample enhances nonspeciÐc metal ion-peptide complexes. This is demonstrated in Fig.…”

Section: Maldi-ms Of Peptide-metal Ion Complexesmentioning

confidence: 99%

Matrix‐assisted laser desorption/ionization mass spectrometry of noncovalent protein–transition metal ion complexes

1998

Self Cite

View full text Add to dashboard Cite

On the mechanism and control of salt-induced resolution loss in matrix-assisted laser desorption/ionization

Cited by 24 publications

References 0 publications

Ionization mechanisms in matrix-assisted laser desorption/ionization mass spectrometry: contribution of pre-formed ions

Ionization mechanisms in matrix-assisted laser desorption/ionization mass spectrometry: contribution of pre-formed ions

Secondary ion-molecule reactions in matrix-assisted laser desorption/ionization

Matrix‐assisted laser desorption/ionization mass spectrometry of noncovalent protein–transition metal ion complexes

Contact Info

Product

Resources

About