Structure, anion, and solvent effects on cation response in ESI-MS

Omari, Isaac; Randhawa, Parmissa; Randhawa, Jaiya; Yu, Jun; McIndoe, J. Scott

doi:10.26434/chemrxiv.7723226

Cited by 3 publications

(3 citation statements)

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“…Furthermore, trace quantities of the organomercuric species [Hg(I) 2 Ph] − (Figure 3, inset), as well as [Pd(1)-Ph 2 (dba)] − were detected, accounting for some of the "missing" Ph-containing ions. However, the mass balance obtained by ESI-MS is not reliable due to differences in surface activities of the various ions in solution, 49 and these activities are not measurable due to the impracticalities of isolating the individual components.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Poisonous Truth about the Mercury Drop Test: The Effect of Elemental Mercury on Pd(0) and Pd(II)ArX Intermediates

Chagunda,

Fisher,

Schierling

et al. 2023

Organometallics

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The mercury drop test is a widely used method often regarded as decisive for discriminating between homogeneous and heterogeneous catalysis in organometallic systems. However, recent research has highlighted the limitations of this test due to the intrinsic reactivity of some organometallic compounds toward elemental mercury. In this study, we used real-time mass spectrometry to investigate the effect of elemental mercury on L n Pd 0 and Pd II ArX intermediates common in palladium-catalyzed cross-coupling reactions. Our findings demonstrate that mercury can interact with both species through redox-transmetallation and amalgamation processes, leading to inhibition of catalytic activity, which would often be misinterpreted as evidence for heterogeneous catalysis. This result further calls into question the widely held assumption that mercury reacts selectively with heterogeneous catalytic species. Therefore, it is important to carefully evaluate the results provided by the mercury drop test and incorporate alternative comprehensive kinetic analysis of the catalyst.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Poisonous Truth about the Mercury Drop Test: The Effect of Elemental Mercury on Pd(0) and Pd(II)ArX Intermediates

Chagunda,

Fisher,

Schierling

et al. 2023

Organometallics

Self Cite

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“…Literature derived reports demonstrated that phosphonium species lacking structural rigidity are typically less responsive than flexible ammonium species, like tetra-n-butylammonium (27). 59 With that premise, it was expected that ion 25 would have a higher intensity ratio relative to 27.…”

Section: Intensity Relative To Positive Ion (%)mentioning

confidence: 99%

Unveiling the Power of Negative Ion Mode ESI-MS: Identifying Species with Remarkable Signal Intensity and Collisional Stability

Warnes,

Chihabi,

Manthorpe

2023

Preprint

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Electrospray ionization mass spectrometry has long been the standard and most prevalent ionization method in mass spectrometry to detect and analyze molecules of low volatility that are relevant biologically, environmentally, and industrially. However, only a small number of analyses are conducted in negative ion mode, which has led to a dogmatic bias toward positive ion mode despite advantageous properties of the negative polarity, including lower background noise and divergent tandem mass spectrometry behavior. We hypothesized that this bias was rooted in the relatively poor ionization efficiency of anionic functional groups seen in biochemistry; to explore this notion herein we evaluated 25 ions based on three criteria: (1) signal intensity relative to a sodium dodecylsulfate internal standard; (2) resistance to collision induced dissociation based on survival of the precursor ion; and (3) diagnostic tandem mass spectrometry behavior. Among these species, highly fluorous ions exhibiting weakly coordinating and hydrophobic properties contributed to enhanced signal intensities. Trifluoromethanesulfonyl-containing ions proved to be unexpectedly labile, while tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion (23) and bis(nonafluoro-1-butane)sulfonimidate (25) were determined to be of optimal signal intensity with signal intensity ratios relative to sodium dodecylsulfate (12 + Na+) of 332.0% ± 25.0% and 939.0% ± 92.0%, respectively, as well as survival yields of 100.0% ± 0.0% and 72.6% ± 0.8% at –50 eV. To further emphasize their optimal signal intensity, ions tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion (23) and bis(nonafluoro-1-butane)sulfonimidate (25) were comparable in signal intensity across solvents of acetonitrile, methanol, isopropanol, water, and their respective 1:1 mixtures. Facile preparation of various salts of bis(nonafluoro-1-butane)sulfonimidate led to additional evaluation of cation effects where the signal intensity ratio ranged from 939.0% ± 92.0% to 3195.0% ± 145.0% across K+, NH4+, Na+, and H+ counter cations. The dogma of negative ion mode being less sensitive was then challenged by the analysis of the signal intensity of ion 25 to tetra-n-butylammonium, tetra-n-butylphosphonium, and (4-methylphenyl)diphenylsulfonium cations. These experiments showed that 25 was more sensitive by between 136.2% ± 5.5% and 180.7% ± 13.8%, thereby successfully challenging the positive polarity bias.

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Section: Ionmentioning

confidence: 99%

Unveiling the Power of Negative Ion Mode ESI-MS: Identify-ing Species with Remarkable Signal Intensity and Collisional Stability

Warnes,

Chihabi,

Manthorpe

2023

Preprint

View full text Add to dashboard Cite

Electrospray ionization mass spectrometry has long been the standard and most prevalent ionization method in mass spectrometry to detect and analyze molecules of low volatility that are relevant biologically, environmentally, and industrially. However, only a small number of analyses are conducted in negative ion mode, which has led to a dog-matic bias toward positive ion mode despite advantageous properties of the negative polarity, including lower back-ground noise and divergent tandem mass spectrometry behavior. We hypothesized that this bias was rooted in the relatively poor ionization efficiency of anionic functional groups seen in biochemistry; to explore this notion herein we evaluated 25 ions based on three criteria: (1) signal intensity relative to a sodium dodecylsulfate internal stand-ard; (2) resistance to collision induced dissociation based on survival of the precursor ion; and (3) diagnostic tandem mass spectrometry behavior. Among these species, highly fluorous ions exhibiting weakly coordinating and hydro-phobic properties contributed to enhanced signal intensities. Trifluoromethanesulfonyl-containing ions proved to be unexpectedly labile, while tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion (23) and bis(nonafluoro-1-butane)sulfonimidate (25) were determined to be of optimal signal intensity with signal intensity ratios relative to sodium dodecylsulfate (12 + Na+) of 332.0% ± 25.0% and 939.0% ± 92.0%, respectively, as well as survival yields of 100.0% ± 0.0% and 72.6% ± 0.8% at –50 eV. To further emphasize their optimal signal intensity, ions tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion (23) and bis(nonafluoro-1-butane)sulfonimidate (25) were comparable in signal intensity across solvents of acetonitrile, methanol, isopropanol, water, and their respective 1:1 mixtures. Facile preparation of various salts of bis(nonafluoro-1-butane)sulfonimidate led to additional evaluation of cation effects where the signal intensity ratio ranged from 939.0% ± 92.0% to 3195.0% ± 145.0% across K+, NH4+, Na+, and H+ counter cations. The dogma of negative ion mode being less sensitive was then challenged by the analysis of the sig-nal intensity of ion 25 to tetra-n-butylammonium, tetra-n-butylphosphonium, and (4-methylphenyl)diphenylsulfonium cations. These experiments showed that 25 was more sensitive by between 136.2% ± 5.5% and 180.7% ± 13.8%, thereby successfully challenging the positive polarity bias.

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Structure, anion, and solvent effects on cation response in ESI-MS

Cited by 3 publications

References 0 publications

Poisonous Truth about the Mercury Drop Test: The Effect of Elemental Mercury on Pd(0) and Pd(II)ArX Intermediates

Poisonous Truth about the Mercury Drop Test: The Effect of Elemental Mercury on Pd(0) and Pd(II)ArX Intermediates

Unveiling the Power of Negative Ion Mode ESI-MS: Identifying Species with Remarkable Signal Intensity and Collisional Stability

Unveiling the Power of Negative Ion Mode ESI-MS: Identify-ing Species with Remarkable Signal Intensity and Collisional Stability

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