Photodissociation of chlorostyrene molecular ions

Collins, G. J.; Kiss, Klara; Pereles, Daniel J.; White, Edward

doi:10.1002/oms.1210210716

Cited by 2 publications

(2 citation statements)

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“…The fragmentations observed for bilirubin are shown in Figure 4. All of the metastables observed in these cases can also be found in normal B/E scans, but in view of the known ability of the photodissociation technique to discriminate between isomers that have identical electron impact spectra (9)(10)(11) and in some cases also identical collisional activation spectra (12), we believe that further investigation is warranted as a means of distinguishing isomeric structures for compounds requiring the use of soft ionization techniques. We are investigating photodissociation as a means of distinguishing bilirubin isomers.…”

Section: Methodsmentioning

confidence: 94%

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Photodissociation of ions generated by soft ionization techniques

Welch¹,

Sams²,

White³

1986

Anal. Chem.

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Photodissociation wlth vlslble light of Ions generated by thesoft Ionization techniques ceslum ion bombardment, fleld desorption, and fleld lonlratlon has been demonstrated. An argon Ion laser was used to irradiate ions In the flrst fleld-free region of a Mattauch-Herrog geometry mass spectrometer. Ions that dlssoclated In this region were detected by means of a linked scan at a constant ratlo of the magnetlc field to the electrlc fleld. Detection of only those ions created by photodlssoclation was accomplished by use of a lock-in amplifier trlggered by a mechanlcal chopper In the laser beam.A variety of compounds were tested for evldence of photodissociation activity. Only compounds with chromophores capable of absorbing visible llght were found to photodlssoclate. Several peptides tested showed no photodissoclation actlvlty. The photodlssoclations of (M + H)+ Ions from methyl red and bilirubin are used to illustrate the potential of the technlque for providlng structural Information. For methyl red the photodlssoclatlon mass spectrum exhlblts several prominent Ions that are very weak or absent In the normal mass spectrum. Improvements, Including use of shorter wavelengths, wlli be needed before thls technlque can become a useful tool for structure determinations.Photodissociation has frequently been applied as a tool for studying the structure of gaseous ions and the thermody-namics and kinetics of gaseous ion processes ( I ) . Most of the studies involved ions consisting of only a few atoms. Ion cyclotron resonance instruments (ICR) and sector instruments equipped with lasers have been used to study the fragmentation of somewhat more complex ions generated by electron impact ionization (EI). These studies have been limited to compounds of low molecular weight, generally less than 200, and low polarity, which are amenable to ionization by EI.They have also been directed, for the most part, to determining the structure of the ions generated rather than to the development of a means for the determination of the structures of organic molecules. E1 mass spectra show extensive fragmentation which provides considerable information on structure. Soft ionization techniques such as chemical ionization (CI), field ionization (FI), field desorption (FD), fast atom bombardment (FAB), and secondary ion mass spectrometry (SIMS) often give little fragmentation, and therefore, the spectra from these techniques contain less information on structure. These last three techniques are generally the methods of choice for obtaining mass spectral information on polar molecules for which E1 is not suitable. Fragmentation can be induced by addition of energy to the ions after their formation through collisions with neutral species. Collision induced dissociation (CID), both at low energies in quadrupole mass spectrometers and high energies in sector mass spectrometers, has been extensively used as a tool for structure determinations. An alternative way to add energy to ions thereby inducing fragmentation is through the absorption of Thi...

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Section: Methodsmentioning

confidence: 94%

“…1979, 51, 1732-1738. (11) Lowry, S. R.; Isenhour, T. L.; Justice, J. B.; McLafferty, F. W.; Dayringer, .…”

Section: Literature Citedmentioning

confidence: 99%

Photodissociation of ions generated by soft ionization techniques

Welch¹,

Sams²,

White³

1986

Anal. Chem.

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Dehalogenation reactions in the fast atom bombardment mass spectrometry of phenothiazine-related drugs

Edom

McKay

Hubbard

et al. 1991

Biol. Mass Spectrom.

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Dehalogenation reactions of selected phenothiazine antipsychotic and tricyclic antidepressant drugs were studied during fast atom bombardment (FAB) mass spectral analysis. All of these halogenated compounds demonstrated the presence of ions corresponding to the loss of a halogen and its replacement by a hydrogen atom. The structure of the dechlorinated ion for chlorpromazine and the source of the hydrogen atoms replacing the chlorine were studied using perdeuterio-glycerol, accurate mass measurement and comparison of the spectrum with its authentic dechlorinated analog. In addition tandem mass spectrometric studies illustrated identical daughter ion spectra for the dechlorinated ion arising during FAB mass spectrometry of cblorpromazine and the analogous ion present in its unhalogenated analog promazine. The dechlorination process once started by exposure to the atom beam during static FAB m a s spectrometry demonstrates an accumulation of dechlorinated ion with time. During continuous flow FAB where the sample is refurbished with time the extent of dechlorination remains relatively constant. The extent of dehalogenation was greater for chlorinated compounds as compared to fluorinated derivatives. The percentage exchange of ChlOriMted compounds ranged from 7.2% to 32.6% while the percentage exchange for triflupromazine was 33%. The recognition that such ions can arise during FAB mass spectrometry avoids the possible misinterpretation of such ions as being due to sample contamination or due to in vivo metabolic dehalogenation during metabolism studies.

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Photodissociation of chlorostyrene molecular ions

Cited by 2 publications

References 4 publications

Photodissociation of ions generated by soft ionization techniques

Photodissociation of ions generated by soft ionization techniques

Dehalogenation reactions in the fast atom bombardment mass spectrometry of phenothiazine-related drugs

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