Feasibility of Formation of Hot Ions in Electrospray

Takáts, Zoltán; Drahos, László; Schlosser, Gitta; Vékey, Károly

doi:10.1021/ac020547r

Cited by 26 publications

(53 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Under typical operating conditions, the curtain gas prevents cluster formation in ESI 26. Spraying dilute aqueous or methanolic solutions of alkali metal halide salts usually results in the appearance of a noise‐like spectrum of low abundance.…”

Section: Resultsmentioning

confidence: 99%

“…This is a simple picture, and there is growing evidence that the mechanism of cluster formation may be different. Recently, we have described a series of events that occur in ESI following the ion evaporation process 26. The ions formed in this way are first accelerated in the Coulomb field of the nanodroplet from which they evaporated from.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Formation of solvated ions in the atmospheric interface of an electrospray ionization triple‐quadrupole mass spectrometer

2003

Self Cite

View full text Add to dashboard Cite

A simple method capable of generating and investigating various solvent clusters and solvated ions was developed. The technique opens a door to studying these complexes on commercially available instruments. Formation of the desired solvated ion in the gas phase was achieved by introducing the appropriate volatile solvent vapour into the curtain gas stream. Capabilities of the technique are illustrated by generating alkali, alkaline earth and transition metal cations solvated by various volatile compounds such as water, methanol and acetonitrile. Depending on the ligands and on the experimental conditions, clusters of 2-100 molecules may be observed. Isotope labelling suggests that these are formed by a re-solvation process in the curtain gas region.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Formation of solvated ions in the atmospheric interface of an electrospray ionization triple‐quadrupole mass spectrometer

2003

Self Cite

View full text Add to dashboard Cite

show abstract

“…Unfolding of Mb ions in the gas phase by collision with nitrogen or argon gas has also been described [18]. It should be, nevertheless, mentioned in this context that a cooling effect of the curtain gas has been suggested to operate during electrospray of small ions [41].…”

Section: Discussionmentioning

confidence: 99%

Interpreting conformational effects in protein nano-ESI-MS spectra

et al. 2003

View full text Add to dashboard Cite

Nano-electrospray-ionization mass spectrometry (nano-ESI-MS) is employed here to describe equilibrium protein conformational transitions and to analyze the influence of instrumental settings, pH, and solvent surface tension on the charge-state distributions (CSD). A first set of experiments shows that high flow rates of N(2) as curtain gas can induce unfolding of cytochrome c (cyt c) and myoglobin (Mb), under conditions in which the stability of the native protein structure has already been reduced by acidification. However, it is possible to identify conditions under which the instrumental settings are not limiting factors for the conformational stability of the protein inside ESI droplets. Under such conditions, equilibrium unfolding transitions described by ESI-MS are comparable with those obtained by other established biophysical methods. Experiments with the very stable proteins ubiquitin (Ubq) and lysozyme (Lyz) enable testing of the influence of extreme pH changes on the ESI process, uncoupled from acid-induced unfolding. When HCl is used for acidification, Ubq and Lyz mass spectra do not change between pH~7 and pH 2.2, indicating that the CSD is highly characteristic of a given protein conformation and not directly affected by even large pH changes. Use of formic or acetic acid for acidification of Ubq solutions results in major spectral changes that can be interpreted in terms of protein unfolding as a result of the increased hydrophobicity of the solvent. On the other hand, Lyz, cyt c, and Mb enable direct comparison of protein CSD (corresponding to either the folded or the unfolded protein) in HCl or acetic acid solutions at low pH. The values of surface tension for these solutions differ significantly. Confirming indications already present in the literature, we observe very similar CSD under these solvent conditions for several proteins in either compact or disordered conformations. The same is true for comparison between water and water-acetic acid for folded cyt c and Lyz. Thus, protein CSD from water-acetic solutions do not seem to be limited by the low surface tension of acetic acid as previously suggested. This result could reflect a general lack of dependence of protein CSD on the surface tension of the solvent. However, it is also possible that the effect of acetic acid on the precursor ESI droplets is smaller than generally assumed.

show abstract

“…By successive collisions with the reagent gas, 1 and 2 complexes formed are either stabilized or broken. Note that phenylethyne (characterized by a DOF = 36) allows a more efficient cooling compared to monoatomic or diatomic collision gases usually used [32]. After many collisions, thermalized 1 and 2 species are obtained at the exit of H0 (hypothesis of model A).…”

Section: E 0 (B) Energy Measurement (Model B)mentioning

confidence: 99%