Proton affinity measurements using ion mobility spectrometry

Tabrizchi, Mahmoud; Shooshtari, Saeed

doi:10.1016/s0021-9614(02)00316-6

Cited by 55 publications

(45 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For the first set of experiments, an equimolar solution of DMMP (PA: 902 kJ mol -1 , BP: 181°C) [21] and p-anisidine (PA: 900 kJ mol -1 , BP: 243°C) [22] was tested to determine whether volatility of analytes at different temperatures and sampling positions contributed to suppression. When the DART set temperature was below the BPs of both compounds (100°C), there was little observed suppression at low concentrations (50 μM) regardless of the sample position, since only very small amounts of either analyte were thermally desorbed (Fig.…”

Section: Ion Suppressionmentioning

confidence: 99%

Sensitivity “Hot Spots” in the Direct Analysis in Real Time Mass Spectrometry of Nerve Agent Simulants

Harris

Falcone

Fernández

2011

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Presented here are findings describing the spatial-dependence of sensitivity and ion suppression effects observed with direct analysis in real time (DART). Continuous liquid infusion of dimethyl methyl phosphonate (DMMP) revealed that ion yield "hot spots" did not always correspond with the highest temperature regions within the ionization space. For instance, at lower concentrations (50 and 100 μM), the highest sensitivities were in the middle of the ionization region at 200°C where there was a shorter ion transport distance, and the heat available to thermally desorb neutrals was moderate. Conversely, at higher DMMP concentrations (500 μM), the highest ion yield was directly in front of the DART source at 200°C where it was exposed to the highest temperature for thermal desorption. In matching experiments, differential analyte volatility was observed to play a smaller role in relative ion suppression than differences in proton affinity and the relative sampling positions of analytes. At equimolar concentrations sampled at the same position, suppression was as high as 26× between isoquinoline (proton affinity 952 kJ mol -1 , boiling point 242°C) and p-anisidine (proton affinity 900 kJ mol -1 , boiling point 243°C). This effect was exacerbated when sampling positions of the two analytes differed, reaching levels of relative suppression as high as 4543.0×±1406.0. To mitigate this level of relative ion suppression, sampling positions and molar ratios of the analytes were modified to create conditions in which ion suppression was negligible.

show abstract

Section: Ion Suppressionmentioning

confidence: 99%

Sensitivity “Hot Spots” in the Direct Analysis in Real Time Mass Spectrometry of Nerve Agent Simulants

Harris

Falcone

Fernández

2011

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

show abstract

“…Absolute values of proton affinities are not always easy to obtain and are often derived from relative measurements with respect to reference molecules. Relative proton affinities are usually measured by means of high-pressure mass spectrometry, with triple quadrupole and ion-trap mass spectrometers [4] or using ion-mobility spectrometry [5].…”

Section: Introductionmentioning

confidence: 99%

Calculation of proton affinity using the CR‐CCSD[T]/ECP method

Morgon

2006

Int J of Quantum Chemistry

View full text Add to dashboard Cite

High-level calculations of proton and electron affinities (PA and EA) of CH 2 X Ϫ and CH 2 CHCHX Ϫ (with X ϭ F, Cl, Br, and I) systems were obtained. The methodology employed in the PA and EA calculations is based on CR-CCSD[T]/B1// MP2/B0 and CCSD(T)/B1//MP2/B0 levels, respectively. B0 is a (small) valence basis set developed by Stevens and colleagues (SBKJC), and B1 is a larger basis set, with extra diffuse and polarization functions (B0 ϩ s, p, d, and f functions). This scheme has been tested on systems containing H, C, and X atoms, and is shown to give good results. The differences between calculated results of PA and EA and the experimental values are in the range of 0.2-4.5 kJ ⅐ mol Ϫ1 and 0.01 to 0.10 eV, respectively.

show abstract

“…Absolute values of proton affinities are not always easy to obtain and are often derived from relative measurements with respect to reference molecules. Relative proton affinities are usually measured by means of high pressure mass spectrometry, with triple quadrupole and ion trap mass spectrometers (Mezzache et al, 2005) or using ion mobility spectrometry (Tabrizchi & Shooshtari, 2003). The importance and utility of the EA extend well beyond the regime of gas-phase ion chemistry.…”

Section: Introductionmentioning

confidence: 99%

Composite Method Employing Pseudopotential at CCSD(T) Level

Morgon¹

2012

Quantum Chemistry - Molecules for Innovations

View full text Add to dashboard Cite

Proton affinity measurements using ion mobility spectrometry

Cited by 55 publications

References 8 publications

Sensitivity “Hot Spots” in the Direct Analysis in Real Time Mass Spectrometry of Nerve Agent Simulants

Sensitivity “Hot Spots” in the Direct Analysis in Real Time Mass Spectrometry of Nerve Agent Simulants

Calculation of proton affinity using the CR‐CCSD[T]/ECP method

Composite Method Employing Pseudopotential at CCSD(T) Level

Contact Info

Product

Resources

About