On the mechanisms by which the charged droplets produced by electrospray lead to gas phase ions

Kebarle, P.; Peschke, Michael

doi:10.1016/s0003-2670(99)00598-x

Cited by 304 publications

(326 citation statements)

References 34 publications

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“…For flow rates typically encountered in LC-MS/MS analysis, the initial electrosprayed droplet is too large to generate a significant number of gas-phase ions. The droplet must decrease in size while maintaining its excess charge through the evaporation of neutral solvent to the point where offspring droplets are formed, which proceed to generate a significant number of gas-phase ions [18,19]. Therefore, increasing the rate of neutral solvent evaporation typically enhances the instrument response and is accomplished through the incorporation of more volatile organic solvents in the mobile phase.…”

Section: Response Enhancementmentioning

confidence: 99%

Enhancing the response of alkyl methylphosphonic acids in negative electrospray ionization liquid chromatography tandem mass spectrometry by post-column addition of organic solvents

Mawhinney

Stanelle

Hamelin

et al. 2007

J. Am. Soc. Mass Spectrom.

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Section: Response Enhancementmentioning

confidence: 99%

Enhancing the response of alkyl methylphosphonic acids in negative electrospray ionization liquid chromatography tandem mass spectrometry by post-column addition of organic solvents

Mawhinney

Stanelle

Hamelin

et al. 2007

J. Am. Soc. Mass Spectrom.

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“…After these emission "bursts", the charge-depleted residual parent returns to an approximately spherical shape [15,16,18]. Repeated evaporation and breakup of the fission products ultimately result in the formation of nanometer-sized droplets from which gas-phase analyte ions are produced [1].Progeny droplets are formed predominantly from the outermost layers of their parent, leading to an enrichment of species with high surface affinity [13,19,20]. In contrast, compounds with low surface affinity accumulate in the charge-depleted residual parent, from where ionization is inefficient [21,22].…”

mentioning

confidence: 99%

“…An alternative framework, the ion evaporation model (IEM), stipulates that charged analytes can be ejected from the droplet surface [24,25]. It has been suggested that large biomolecular ions are formed predominantly via the CRM mechanism [2, 26 -29], and that the IEM is operative for relatively small analytes [1]. In addition, proposals for scenarios involving elements of both models have been put forward [30,31].…”

mentioning

confidence: 99%

“…In addition, proposals for scenarios involving elements of both models have been put forward [30,31]. A solvent droplet is said to be at the Rayleigh limit when its net charge reaches a value Q R that is given by [1,32] where 0 is the permittivity of the vacuum, and ␥ is the surface tension. In the ESI-MS literature the relationship between Q R and droplet stability is often treated somewhat casually, using statements such as [33] "[it was] found that as the solvent evaporated the density of charges on the droplet surface would increase to a critical value, now known as the 'Rayleigh limit', at which Coulomb repulsion would overcome surface tension.…”

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confidence: 99%

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A simple model for the disintegration of highly charged solvent droplets during electrospray ionization

Konermann

2009

J. Am. Soc. Mass Spectrom.

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This work uses a minimalist model for deciphering the opposing effects of Coulomb repulsion and surface tension on the stability of electrosprayed droplets. Guided by previous observations, it is assumed that progeny droplets are ejected from the tip of liquid filaments that are formed as protrusions of an initially spherical parent. Nonspherical shapes are approximated as assemblies of multiple closely spaced beads. This strategy greatly facilitates the calculation of electrostatic and surface energies. For a droplet at the Rayleigh limit the model predicts that growth of a very thin filament is a spontaneous process with a negligible activation barrier. In contrast, significant barriers are encountered for the formation of larger diameter filaments. These different barrier heights favor highly asymmetric droplet fission because the dimensions of the filament determine those of the ejected droplet(s). Substantial charge accumulation occurs at the filament termini. This allows each progeny droplet to carry a significant fraction of charge, despite its very small volume. In the absence of a long connecting filament, relieving electrostatic stress through progeny droplet emission would be ineffective. The model predicts the prevalence of fission events leading to the formation of several progeny droplets, instead of just a single one. Ejection bursts are followed by collapse back to a spherical shape. The resulting charge depleted system is incapable of producing additional progeny droplets until solvent evaporation returns it to the Rayleigh limit. Despite the very simple nature of the model used here, all of these predictions agree with experimental data. E lectrospray ionization (ESI) mass spectrometry (MS) has evolved into one of the most versatile and widely used analytical techniques. The ESI process itself has been subject of numerous studies (see, e.g., [1][2][3][4][5][6][7][8][9][10][11][12] and references therein). Analyte solution is passed through a metal capillary to which high voltage has been applied, and solvent droplets emanate from the tip of a Taylor cone at the capillary outlet [11]. Each droplet carries a net charge due to protons or other cationic species that reside at the air/liquid interface. Solvent evaporation and droplet fission are fundamental elements of the ESI process. Evaporation increases the surface charge density to a point where fission occurs. The disintegration process triggered in this way is highly asymmetric, leading to the formation of several small progeny droplets that carry away only a small fraction of mass, but a disproportionately high amount of charge [13,14]. High-speed imaging is an important tool for gaining insights into the breakup mechanism [15,16]. More recently, the rapid solidification of charged nanodroplets using sol-gel techniques has provided a means to capture transient droplet shapes and study them by microscopy [17]. Also, molecular dynamics simulations represent an interesting approach in this area [9,10]. All those studies reveal that disintegrati...

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Native Mass Spectrometry as a Tool in Structural Biology

Lorenzen

Duijn

2010

CP Protein Science

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Native mass spectrometry (native MS) gives information about the composition, topological arrangements, dynamics, and structural properties of protein complexes. The mass range is principally unlimited and highly dynamic, allowing the detection of small subunits and large complexes within the same measurement. The amount of protein needed for an analysis is, compared to most other structural biology methods, very low. This unit provides an introduction to native MS. It starts with an explanation of the basic method and details on how to measure intact proteins and protein complexes, and continues with the study of dynamics and complex stability in the gas phase. The final section discusses the most recent extension to the native MS field, ion mobility, which allows the direct assessment of the structural properties of the complexes of interest.

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On the mechanisms by which the charged droplets produced by electrospray lead to gas phase ions

Cited by 304 publications

References 34 publications

Enhancing the response of alkyl methylphosphonic acids in negative electrospray ionization liquid chromatography tandem mass spectrometry by post-column addition of organic solvents

Enhancing the response of alkyl methylphosphonic acids in negative electrospray ionization liquid chromatography tandem mass spectrometry by post-column addition of organic solvents

A simple model for the disintegration of highly charged solvent droplets during electrospray ionization

Native Mass Spectrometry as a Tool in Structural Biology

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