‘Wet chemistry’ and crystallochemistry reasons for acidic matrix suppression by quaternary ammonium salts under matrix‐assisted laser desorption/ionization conditions

Kosevich, M. V.; Boryak, Oleg A.; Chagovets, Vitalij V.; Pashynska, V. A.; Orlov, V. V.; Stepanian, S. G.; Shelkovsky, Vadim S.

doi:10.1002/rcm.3020

Cited by 11 publications

(11 citation statements)

References 101 publications

(85 reference statements)

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“…The second group of changes in the mass spectral pattern is connected with the transformations of the Cat 2+ •Cl -(m/z 549/551) ion. This ion appears in the mass spectra at the lowest CV value and starts to decrease from a CV of 20 V on (Figure 1b features of MALDI mass spectra of quaternary ammonium compounds obtained with DHB matrix, which were reported in our previous paper [34]. In accord with these findings, a chemical substitution reaction of the Clanion of the quaternary ammonium salt ethonium for the (DHB -H)anion of organic acid DHB must take place in water solution at the stage of sample preparation.…”

Section: Electrospray Mass Spectrasupporting

confidence: 79%

“…As for the MALDI technique, the necessity to account for the effect of possible chemical reactions of the 2,5-dihydroxybenzoic acid (DHB) matrix compound with basic analytes on the mass spectra has been demonstrated [34]. In particular, for quaternary ammonium salts it was proved that the competitive substitution of an inorganic anion of the salts by organic (DHB -H)anion in the course of sample preparation leads to formation of a new salt Cat + •(DHB -H)or (Cat 2+ •2(DHB -H)ion) [34]. Due to this effect the MALDI mass spectra contain the latter new salt ion species and are characterized by ions related to the cation of the initial salt in the positive ion mode and [DHB -H]anions in the negative ion mode [34,35].…”

Section: Electrospray Mass Spectramentioning

confidence: 99%

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Variable Electrospray Ionization and Matrix-Assisted Laser Desorption/ Ionization Mass Spectra of the Bisquaternary Ammonium Salt Ethonium

Pashynska¹,

Kosevich²

2015

Mass Spectrom Purif Tech

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Determination of a single "fingerprint" mass spectrum of a biologically active compound, required for compound identification in mixtures and biological materials in such applied tasks as ecological monitoring and biological imaging, may become a nontrivial problem for labile compounds whose mass spectra depend strongly on the applied experimental conditions. In the present communication, qualitatively different mass spectral patterns obtained for the bisquaternary ammonium salt ethonium Cat 2+ •2Clunder varied conditions of electrospray ionization and matrixassisted laser desorption/ionization (MALDI) are described and systematized. It is shown that qualitative changes in the electrospray mass spectra of ethonium occur upon a cone voltage increase from 10 V to 100 V, which are caused by the subsequent appearance and destruction of several primary ions: the intact dication Cat 2+ , the dication-counterion cluster Cat 2+ •Cland[Cat-H] + and [Cat-CH 3 ] + ions. Novel experimental evidence of survival of the gas-phase dication Cat 2+ with the shortest possible distance of ca 4 Ǻ between the quaternary nitrogen atoms provided by two CH 2 groups and Cat 2+ fragmentation with preservation of the doubly charged state of the fragments are revealed under soft electrospray conditions. The interpretation of the MALDI mass spectrum is made taking into account the formation of a salt of the bisquaternary ammonium base and 2,5-dihydroxybenzoic acid, which results in the absence of any chlorine-containing ions in the mass spectra and a fragment ion distribution that is different from that observed under electrospray ionization conditions. The main mass spectral features revealed for ethonium may aid in the identification of other types of bisquaternary ammonium compounds.

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Section: Electrospray Mass Spectrasupporting

confidence: 79%

Section: Electrospray Mass Spectramentioning

confidence: 99%

Variable Electrospray Ionization and Matrix-Assisted Laser Desorption/ Ionization Mass Spectra of the Bisquaternary Ammonium Salt Ethonium

Pashynska¹,

Kosevich²

2015

Mass Spectrom Purif Tech

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“…Kosevich et al . suggested that the MSE of the QASs might be due to the formation of an ammonium salt of an acidic matrix in the MALDI solution,22 which in our case should not be a major reason, because of the large excess of matrix in our experiments, e.g., a mole ratio of matrix to QAS at about 1000:1. Furthermore, in our experiments a strong MSE was also observed with some neutral matrices that could not form the matrix ammonium salt.…”

mentioning

confidence: 63%

“…However, these reactions cannot justify the strong MSE and ASE of the quaternary ammonium salts (QASs) studied in this work, because the NR

_{4}^{+}

are preformed ions and not the result of secondary gas‐phase reactions. In the literature, a number of quaternary ammonium surfactants have successfully been used to suppress matrix ions in an attempt to improve the MALDI TOF MS analysis of low molecular weight analytes 22–25. Kosevich et al .…”

mentioning

confidence: 99%

Matrix suppression and analyte suppression effects of quaternary ammonium salts in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry: an investigation of suppression mechanism

Lou¹,

Dongen²,

Vekemans³

et al. 2009

Rapid Comm Mass Spectrometry

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In the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) analysis of some quaternary ammonium salts (QASs), very clean spectra of the quaternary ammonium ions were recorded with a strong matrix suppression effect (MSE). The QASs also showed a considerable analyte suppression effect (ASE). It was demonstrated that the MSE and ASE of the QASs can be explained well by the cluster ionization model. According to this model, MALDI ions are formed from charged matrix/analyte clusters. Various analyte ions and matrix ions might coexist in the cluster, and they will compete for the limited number of net charges available. If enough quaternary ammonium ions are present in the cluster, they will take away the net charges, thus resulting in the MSE and ASE. Our results also suggest that 'the cluster ionization model' is not in conflict with 'the theory of ionization via secondary gas-phase reactions'. The initial MALDI ions produced from charged matrix/analyte clusters will collide with other molecules or ions in the MALDI plume. Depending on the properties of the initial ions and the composition of the MALDI plume, secondary gas-phase reactions might result from these collisions. The final ions observed are the combined results of 'cluster ionization' and 'ionization via secondary gas-phase reactions'.

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“…In the literature, several ammonium salts and surfactants have been used to suppress matrix ions to enhance analysis of low molecular weight analytes . Additionally, it was shown that ammonium salts as α‐CHCA matrix additive could be used to suppress α‐CHCA matrix clusters and enhance tryptic peptide detection.…”

Section: Discussionmentioning

confidence: 99%

Improved spectra for MALDI MSI of peptides using ammonium phosphate monobasic in MALDI matrix

Uçal

Özpınar

2018

J Mass Spectrom

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MALDI mass spectrometry imaging (MSI) enables analysis of peptides along with histology. However, there are several critical steps in MALDI MSI of peptides, 1 of which is spectral quality. Suppression of MALDI matrix clusters by the aid of ammonium salts in MALDI experiments is well known. It is asserted that addition of ammonium salts dissociates potential matrix adducts and thereafter decreases matrix cluster formation. Consequently, MALDI MS sensitivity and mass accuracy increase. Up to our knowledge, a limited number of MALDI MSI studies used ammonium salts as matrix additives to suppress matrix clusters and enhance peptide signals. In this work, we investigated the effect of ammonium phosphate monobasic (AmP) as alpha-cyano-4-hydroxycinnamic acid (α-CHCA) matrix additive in MALDI MSI of peptides. Prior to MALDI MSI, the effect of varying concentrations of AmP in α-CHCA was assessed in bovine serum albumin tryptic digests and compared with the control (α-CHCA without AmP). Based on our data, the addition of AmP as matrix additive decreased matrix cluster formation regardless of its concentration, and specifically, 8 mM AmP and 10 mM AmP increased bovine serum albumin peptide signal intensities. In MALDI MSI of peptides, both 8 and 10 mM AmP in α-CHCA improved peptide signals especially in the mass range of m/z 2000 to 3000. In particular, 9 peptide signals were found to have differential intensities within the tissues deposited with AmP in α-CHCA (AUC > 0.60). To the best of our knowledge, this is the first MALDI MSI of peptides work investigating different concentrations of AmP as α-CHCA matrix additive to enhance peptide signals in formalin-fixed paraffin-embedded (FFPE) tissues. Further, AmP as part of α-CHCA matrix could enhance protein identifications and support MALDI MSI-based proteomic approaches.

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‘Wet chemistry’ and crystallochemistry reasons for acidic matrix suppression by quaternary ammonium salts under matrix‐assisted laser desorption/ionization conditions

Cited by 11 publications

References 101 publications

Variable Electrospray Ionization and Matrix-Assisted Laser Desorption/ Ionization Mass Spectra of the Bisquaternary Ammonium Salt Ethonium

Variable Electrospray Ionization and Matrix-Assisted Laser Desorption/ Ionization Mass Spectra of the Bisquaternary Ammonium Salt Ethonium

Matrix suppression and analyte suppression effects of quaternary ammonium salts in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry: an investigation of suppression mechanism

Improved spectra for MALDI MSI of peptides using ammonium phosphate monobasic in MALDI matrix

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