Field desorption mass spectrometry of quaternary ammonium salts: Cluster ion formation

Veith, H. J.

doi:10.1002/oms.1210110609

Cited by 53 publications

(11 citation statements)

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“…ϩ is a long known phenomenon in FD mass spectra of salts [47,48]; the value of n rises the larger the amount of sample placed onto the emitter surface and also depends on the actual salt. The assignment of the signals at higher m/z is further justified from the comparison of the experimental and calculated isotopic patterns, which reveal the presence of one boron atom at m/z 415.3 and two at m/z 666.4 due to the content of 10 B besides the most abundant boron isotope 11 B.…”

Section: Full Scan Lifdi Mass Spectra Of Ilmentioning

confidence: 99%

Liquid injection field desorption/ionization-mass spectrometry of ionic liquids

Gross

2007

J. Am. Soc. Mass Spectrom.

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Ten ionic liquids based on four types of organic cations, C ϩ (imidazolium, pyrrolidinium, pyridinium, and phosphonium), combined with various types of anions, AϪ, were analyzed by liquid injection field desorption/ionization-(LIFDI) mass spectrometry. For the purpose of LIFDI analysis the ionic liquids were dissolved in methanol, acetonitrile or tetrahydrofuran at concentrations of 0.01-0.1 l mL Ϫ1 . The measurements were performed on a double-focusing magnetic sector instrument. In all ionic liquid LIFDI spectra, the intact cation of the compound yielded the base peak accompanied by cluster ions of the general formula [C 2 A] ϩ and occasionally [C 3 A 2 ] ϩ . Tandem mass spectrometry and reconstructed ion chromatograms were employed to reveal the identity of the observed ions. Although limited to positive-ion mode, LIFDI also provided analytical information on the anions due to cluster ion formation. Depending on actual emitter condition and ionic liquid the limit of detection in survey scans was determined to 5-50 pg of ionic liquid. [1][2][3]. Consequently, there is a need for the development of methods for their analysis, be it for the sake of checking their purity, to verify their absence in products from processes where ILs are involved, or to monitor their distribution in the environment as a result of their long-term usage.Mass spectrometry (MS) offers various methods for the analysis of ionic analytes, with electrospray ionization (ESI) [4,5] and matrix-assisted laser desorption/ ionization (MALDI) [6,7] presently being the widest known techniques for that purpose. In addition, fast atom bombardment (FAB) [8,9] as well as field desorption (FD) [10 -12] Although being the longest established method for ionic analyte analysis, FD has been overlooked in this scenario of mass spectral techniques for IL analysis. Field desorption (FD) is known since the 1970s as a soft desorption/ionization method in mass spectrometry [10, 28 -30]. FD-MS has proven capabilities in analyzing nonionic low-to medium polarity compounds [12].FD employs strong electric fields in the order of 10 10 V m Ϫ1 (1 V Å Ϫ1 ) to effect the ionization of atoms and molecules [11,12,31]. The necessary field strength is normally achieved by setting whisker-bearing wiresso-called activated emitters [32][33][34]-to high electric potential of typically 10 -12 kV opposed to a counter electrode at ϳ2 mm distance. With the emitter at positive polarity, electron tunneling becomes possible from the analyte residing on the activated emitter's large surface into the emitter material. The analyte is thereby ionized very softly and the molecular ions generated are immediately extracted into the mass analyzer by action of the same electric field.Due to the advent of liquid injection field desorption/ionization (LIFDI) [35][36][37] the FD experiment can now be conducted easier, faster, and with more reproducibility than with the previous methodology of sample supply outside the ion source. If required, LIFDI offers fully inert sample transfer from se...

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Section: Full Scan Lifdi Mass Spectra Of Ilmentioning

confidence: 99%

Liquid injection field desorption/ionization-mass spectrometry of ionic liquids

Gross

2007

J. Am. Soc. Mass Spectrom.

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“…The ion (1) decomposes, predominantly by heterolysis of the N-Chenlyl bond, into a C7@ ion (m/e=91). This charge transfer from the N atom to the aromatic ring is also observed in ion (2). but the formation of the C,HY ions from (2) and from (3) is associated with a hydrogen migration.…”

mentioning

confidence: 66%

“…This charge transfer from the N atom to the aromatic ring is also observed in ion (2). but the formation of the C,HY ions from (2) and from (3) is associated with a hydrogen migration. Apparently, less energy is required for the elimination of N-methylmethyleneamine from ( I ) than in the case of the ions (2) and (3) since the proportion of competing decompositions in (2) and (3) increases considerably.…”

mentioning

confidence: 66%

“…The N,N-dimethylaminotropylium structure, both in the case of ion (3) as well as partially after isomerization of (2), is proven by the occurrence of more intense signals at m / e = 90 and 89 in comparison to the CA spectrum of (1). The formation of these ions can be explained in terms of homolysis of the C-N bond and N,N-dimethylamine elimination, respectively.…”

mentioning

confidence: 96%

“…but the formation of the C,HY ions from (2) and from (3) is associated with a hydrogen migration. Apparently, less energy is required for the elimination of N-methylmethyleneamine from ( I ) than in the case of the ions (2) and (3) since the proportion of competing decompositions in (2) and (3) increases considerably. In the CA spectrum of (2) the [ M e -CH,] ion (m/e= 118) reaches cu.…”

mentioning

confidence: 99%

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