An experimental study of the electrospraying of water in air at atmospheric pressure

López-Herrera, José M.; Barrero, Antonio; Boucard, A.; Loscertales, Ignacio G.; Márquez, Manuel

doi:10.1016/j.jasms.2003.10.018

Cited by 81 publications

(53 citation statements)

References 21 publications

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“…Also, the solution used must have a certain conductivity and surface tension. Too high a conductivity and surface tension (such as water)°prevent°the°formation°of°a°stable°conejet° [27]. The conejet mode could be obtained with 2-butanol and acetonitrile.…”

Section: Resultsmentioning

confidence: 99%

Shrinking droplets in electrospray ionization and their influence on chemical equilibria

Wortmann

Kistler-Momotova

Zenobi

et al. 2007

J. Am. Soc. Mass Spectrom.

113

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We investigated how chemical equilibria are affected by the electrospray process, using simultaneous in situ measurements by laser-induced fluorescence (LIF) and phase Doppler anemometry (PDA). The motivation for this study was the increasing number of publications in which electrospray ionization mass spectrometry is used for binding constant determination. The PDA was used to monitor droplet size and velocity, whereas LIF was used to monitor fluorescent analytes within the electrospray droplets. Using acetonitrile as solvent, we found an average initial droplet diameter of 10 m in the electrospray. The PDA allowed us to follow the evolution of these droplets down to a size of 1 m. Rhodamine B-sulfonylchloride was used as a fluorescent analyte within the electrospray. By spatially resolved LIF it was possible to probe the dimerization equilibrium of this dye. Measurements at different spray positions showed no influence of the decreasing droplet size on the monomer-dimer equilibrium. However, with the fluorescent dye pair DCM and oxazine 1 it was shown that a concentration increase does occur within electrosprayed droplets, using fluorescence resonance energy transfer as a probe for the average pair distance. ( An important aspect of the highly dynamic electrospray process concerns the shrinking droplets. After the droplet creation, solvent evaporation and Coulomb explosions lead to a decrease of droplet size until all solvent has evaporated and the final desolvated and ionized analytes are produced. A decrease of droplet size resulting from solvent evaporation will lead to a concentration increase of nonvolatile analytes within the droplets. For dissolved species that participate in a chemical equilibrium, such as free and bound states of partners that can form a noncovalent complex, the question arises whether the increasing concentrations affect the equilibrium position. Given that binding constant determination with ESI-MS usually relies on measuring the relative amounts of free and bound species, a perturbation of the equilibrium introduced by the shrinking droplets would influence the results of such an experiment. Recent studies show that the time between droplet creation and production of desolvated ions in ESI is within milliseconds [5]. In other words, if the association and dissociation reactions are fast, an equilibrium should be able to track a concentration increase within the droplets.The shrinking droplet volume also leads to Coulomb explosions/droplet fission, when the mutual repulsion of charges is high enough to overcome the surface tension of the droplet. The parent droplet ejects several smaller offspring droplets, which together carry 10 -25% of the charge, but only about 5% of the mass of the original droplet [9]. These offspring droplets then segregate within the electrospray, as shown theoretically by Wilhelm et al. [10]. Analytes will not generally be evenly distributed between the parent and offspring droplets. Partitioning processes, which have been investigated by several research g...

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Section: Resultsmentioning

confidence: 99%

Shrinking droplets in electrospray ionization and their influence on chemical equilibria

Wortmann

Kistler-Momotova

Zenobi

et al. 2007

J. Am. Soc. Mass Spectrom.

113

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“…Fine droplets of uniform size can be obtained by using the electrospray method [1][2][3][4][5]. This method is used for fine particle production [6,7], ionization [7][8][9], etc.…”

Section: Introductionmentioning

confidence: 99%

An Electrospray Method Using a Multi‐Capillary Nozzle Emitter

et al. 2007

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A multi-capillary nozzle emitter consisting of one metal plate with capillary nozzles and a ring type counter electrode was used as a multi-electrospray atomizer. The number of capillary nozzles, flow rate of the liquid and the interval between the capillary nozzles were changed, and the droplet diameter and the voltage required for a steady cone-jet mode were measured. For the multi-capillary nozzle emitter, the interaction between the capillary nozzles is the important factor for obtaining fine droplets of uniform size. These fine droplets are obtained when there is only a small interaction between the capillary nozzles, and the equations obtained from the single capillary nozzle case are also applicable for the multicapillary nozzle emitter. When the number of capillary nozzles decreases (a situation which is not good for obtaining a large amount of droplets) or the interval between the capillary nozzles increases, the interaction between the capillary nozzles can be reduced. As the number of capillary nozzles increase, a higher voltage is required to obtain a fine droplet of uniform size.

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“…Although not shown in this figure, the results with no gas were similar to those obtained at the lowest gas settings shown. Increasing the composition of organic solvent also served to suppress corona discharge attributable to a reduction in the conductivity of the electrosprayed® solution® [19].…”

Section: Resultsmentioning

confidence: 99%

“…Typical nanoflow electrospray systems display good stability for samples consisting of 20 to 100% organic solvent. However, stability can be an issue when running predominantly aqueous solvents because of the high surface tension of water [18] and the onset of corona discharge [19]. As a result, many of the nanoLC-MS systems described in the literature limit the gradient to avoid solvent conditions comprised of greater than approximately 90% water [15,20,21].…”

mentioning

confidence: 99%

Stable gradient nanoflow LC-MS

Schneider¹,

Guo²,

Fell³

et al. 2005

J. Am. Soc. Mass Spectrom.

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This paper demonstrates improved nanoflow LC-MS performance on a QqTOF instrument with the incorporation of a heated nanoflow interface (particle discriminator) and a nebulizer assisted sprayer. It is shown that the nebulizer broadens the usable range of electrospray potentials, simplifying the tuning procedure, particularly for negative mode nanoflow gradients. The improved desolvation capability with the particle discriminator results in signal/noise improvements of approximately 3.5ϫ for negative ion mode samples prepared in predominantly acidified water as well as increased ion current stability. For nanoLC applications, the combined desolvation capabilities of a counter-current gas and heated laminar flow chamber provide reduced background, increased signal stability, reduced background drift, and improved protein sequence coverage when compared with data generated with only a counter-current gas for desolvation. This system is capable of subfemtomole nanoflow LC-MS sensitivity in both positive and negative ion mode across the solvent gradient. and electrospray ionization-mass spectrometry (ESI-MS) has evolved substantially since its initial implementation in the 1980s [1]. Traditional LC systems operated at solvent flow rates that were orders of magnitude higher (hundreds of L/min to mL/min) than those used for mass spectrometry (tens of L/ min), resulting in the need for solvent flow splitters [2]. Some of the subsequent improvements were focused on the use of nebulizer gases [3] and heating [4,5] for stabilization of the electrospray process to accommodate higher LC solvent flows.An alternate approach involves modification of the LC system to accommodate separations within the nanoflow regime [6,7]. Nanoflow LC-MS offers benefits in terms of sensitivity, solvent consumption, and sample consumption when compared with higher flow rate LC-MS, however, it can be much more difficult to operate. Nanoflow sprayers are typically fabricated from tapered fused silica capillary resulting in the need for some type of surface coating [8,9], inserted electrode [10,11], conductive union [6, 12, 13], or dialysis membrane [14] for application of the electrospray potential. Alternatively, sprayers can be fabricated from conductive materials, such as stainless steel, [15], however, tapered stainless steel sprayers are much more difficult to fabricate than fused silica sprayers. An additional benefit associated with fused silica sprayers is that the analytical column may be packed directly into the tapered sprayer, eliminating any post-column dead volume [16,17].A necessary but understated requirement for gradient elution in nanoLC-MS is an electrospray system that is capable of stable operation over a wide range of solvent compositions, particularly for samples containing both hydrophilic and hydrophobic components. Typical nanoflow electrospray systems display good stability for samples consisting of 20 to 100% organic solvent. However, stability can be an issue when running predominantly aqueous solvents because of the h...

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An experimental study of the electrospraying of water in air at atmospheric pressure

Cited by 81 publications

References 21 publications

Shrinking droplets in electrospray ionization and their influence on chemical equilibria

Shrinking droplets in electrospray ionization and their influence on chemical equilibria

An Electrospray Method Using a Multi‐Capillary Nozzle Emitter

Stable gradient nanoflow LC-MS

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