Mass transport and ion pairing effects in electrohydrodynamic mass spectrometry

Reynolds, Johnny D.; Cook, Kelsey D.

doi:10.1016/0168-1176(90)85008-p

Cited by 4 publications

(3 citation statements)

References 6 publications

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“…In investigations of various physicochemical phenomena or applications of various techniques usually there are some favorite objects of study, which allow the soundest demonstration of distinctive features of a certain phenomenon or the highest performance of a certain technique. Organic dications of bisquaternary ammonium (along with phosphonium and sulfonium) salts as compounds with fixed pre‐formed charges are among such favorite objects in desorption mass spectrometric techniques,1–15 since, before the introduction of electrospray ionization (ESI), they were practically the only easily accessible species for investigation of multiply charged organic ions. Even against the background of current advances in ESI with generation of ions bearing several tens of charges,16–18 doubly charged ions still remain an important model for developing approaches for the investigation of multiply charged species and elucidation of mechanisms of ion formation 19–25…”

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confidence: 99%

“…The basic principles of behavior of salts of bisquaternary ammonium compounds under mass spectrometric conditions, developed on the basis of several decades of studies in the ‘pre‐electrospray’ era mainly by field desorption (FD), fast atom bombardment (FAB), solid and liquid secondary ion mass spectrometry (SIMS), 252‐Cf plasma desorption and laser desorption1–15 of a multitude of substances (many of which possess versatile biological activity), can be summarized as follows. The abundance of doubly charged ions in comparison with all other types of ions in these spectra was usually relatively small.…”

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On the stability of the organic dication of the bisquaternary ammonium salt decamethoxinum under liquid secondary ion mass spectrometry

Pashynska

Kosevich

Gömöry

et al. 2005

Rapid Comm Mass Spectrometry

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In the course of a liquid secondary ion mass spectrometric (SIMS) investigation on a bisquaternary ammonium antimicrobial agent, decamethoxinum, unusual pathways of fragmentation of the organic dication M2+ of this bisquaternary salt, with preservation of the doubly charged state of the fragments, were observed. To reveal the structural and electronic parameters of decamethoxinum, which are responsible for the stabilization of its organic dication in the gas phase, a comprehensive SIMS study using metastable decay, collision-induced dissociation and kinetic energy release techniques complemented by ab initio quantum chemical calculations was performed. Pathways of fragmentation of two main precursors originating from decamethoxinum-organic dication M2+ and its cluster with a Cl- counterion [M.Cl]+-and a number of their primary fragments were established and systematized. Differences in the pathways of fragmentation of M2+ and [M.Cl]+ were revealed: the main directions of [M.Cl]+ decay involve dequaternization similar to thermal degradation of this compound, while in M2+ fragmentation via loss of one and two terminal radicals with preservation of the doubly charged state of the fragments dominates over charge separation processes. It was shown that pairing of the dication with a Cl- anion does not preserve the complex from fragmentation via separation of two positively charged centers or neutralization (dequaternization) of one such center. At the same time the low abundance of M2+ in the SIMS spectra is to a larger extent controlled by a probability of M2+ association with an anion than by the decay of the dication per se. Quantum chemical calculations of the structural and electronic parameters of the decamethoxinum dication have revealed at least three features which can provide stabilization of the doubly charged state. Firstly, in the most energetically favorable stretch conformation the distance between the quaternary nitrogens (rN1-N2=1.39 nm) is relatively large. Secondly, an intramolecular solvation of quaternary groups by carbonyl oxygens of the adjacent groups of the dication occurs, which contribute to structural stabilization. Thirdly, an important feature of the electronic structure of the dication is the presence of a partial negative charge on the nitrogen atoms and smearing of a positive charge mainly over the hydrogens of alkyl groups attached to the quaternary nitrogens, which reduces the net repulsion between the quaternary groups. The possible influence of charge smearing on the kinetic energy released on the dication fragmentation is discussed.

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On the stability of the organic dication of the bisquaternary ammonium salt decamethoxinum under liquid secondary ion mass spectrometry

Pashynska

Kosevich

Gömöry

et al. 2005

Rapid Comm Mass Spectrometry

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“…18 It is also known that, albeit to a lesser extent compared to ESI-MS, multiply charged cations can be detected by MALDI-TOF. 19 On the other hand, it has been previously reported that peptides derivatised with two quaternary ammonium tags form only singly (and not doubly) charged ions in MALDI-TOF, 9a a finding earlier reported for model "double-quads". 20 As multiply charged species are a nuisance that complicates the interpretation of the MS data, we were relieved to find out that our tags should not cause this problem, and moved on to test them with model peptides.…”

Section: Charge State Of Trityl Clustersmentioning

confidence: 78%