Interference peaks in mass analysed ion kinetic energy spectra

Ast, T.; Bozorgzadeh, M. H.; Wiebers, J. L.; Beynon, J. H.; Brenton, A.G.

doi:10.1002/oms.1210140606

Cited by 55 publications

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References 13 publications

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“…Die Fragmentierung wird in diesem Fall so ausgepragt, dass auch Ionen rnit kleineren Massen registriert werden, die ohne Bedeutung fur eine Sequenzanalyse sind; [18] und [19] angegeben.…”

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Nachweis von Fragment‐Genesen im Massenspektrometer. 5. Mitteilung Aminosäure‐Sequenzanalyse: Vergleich der DADI/MIKE‐, ‘linked scan’‐ und Kollisionsaktivierungs‐Spektrometrie an aliphatischen Aminosäuren

Steinauer

Walther

Schlunegger

1980

Helvetica Chimica Acta

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The amino acid sequence in tripeptides and tetrapeptides has been analyzed by DADUMIKE and B/E-'linked stun ' spectrometry, as well as by collisional activation in the first and second field free region of a mass spectrometer embodying the inverse Nier-Johnson geometry. Collisional activation enhances the intensity of fragment ions. Einleitung. -Schon seit langerer Zeit wird die Massenspektrometrie in der Peptidanalytik eingesetzt. Die Aminosauresequenz von Oligopeptiden lasst sich damit an kleinen Substanzmengen ermitteln [ l ] [ 2 ] . In Peptidenwie in anderen Polymeren -I wiederholt sich ein Grundstrukturelement periodisch; das fuhrt zu einer Periodizitat in der massenspektrometrischen Fragmentierung. Entsprechende ionisierte Fragmente lassen sich im konventionellen Massenspektrum nachweisen. Oft sind aber diese wichtigen, sequenzcharakteristischen Ionen nicht leicht zu erkennen, da sie durch Signale konkurrenzierender Fragmentierungen uberdeckt werden. Neue Wege eroffnete die DADI/MIKE-Spektrometrie'), weil damit genetische Beziehungen zwischen einem Ion und dessen Folge-Ionen nachgewiesen werden [3] [4]. Auf diese Weise lassen sich auch sequenzcharakteristische Fragment-Ionen aus Oligopeptiden selektiv verfolgen. Die genetische Reihenfolge und die Masse dieser ausgewahlten Ionen fuhren zur Aminosaure-Sequenz des untersuchten Oligopeptides [5]. Eine solche Analyse lasst sich grundsatzlich auch an unreinen Proben [6] oder an Peptid-Gemischen [7] durchfuhren.

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“…Die Fragmentierung wird in diesem Fall so ausgepragt, dass auch Ionen rnit kleineren Massen registriert werden, die ohne Bedeutung fur eine Sequenzanalyse sind; [18] und [19] angegeben.…”

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“…B. durch Zerfalle im ersten FFR und bei der BIE-'linked scan'-Spektrometrie im zweiten FFR. Unter gewissen Voraussetzungen (siehe[18][19][20]) werden diese Zerfalle aber trotzdem registriert. Auch beiFig.2.…”

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Nachweis von Fragment‐Genesen im Massenspektrometer. 5. Mitteilung Aminosäure‐Sequenzanalyse: Vergleich der DADI/MIKE‐, ‘linked scan’‐ und Kollisionsaktivierungs‐Spektrometrie an aliphatischen Aminosäuren

Steinauer

Walther

Schlunegger

1980

Helvetica Chimica Acta

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“…From Eqns (3 and 4) the range of apparent masses mf and the range of the electric sector voltages can be evaluated for reaction (1) occurring in the accelerating region of the ion source. Setting f = 0 is equivalent to regarding ions m2+ generated in the ion source before acceleration, i.e.…”

Section: Resultsmentioning

confidence: 99%

Further interference peaks in mass analysed ion kinetic energy spectra

Schaldach¹,

Grützmacher²

1980

Org. Mass Spectrom.

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It is shown that interference peaks in mass analysed ion kinetic energy spectra can also occur from ions decomposing in the accelerating region of the ion source. INTRODUCHONRecently, Beynon and co-workers reported' on interference peaks in mass analysed ion kinetic energy (MIKE) spectra. We have been confronted with this problem too,' and arrived principally at the same explanations concerning the origins of certain interference peaks in MIKE spectra.' However, in addition to the cases mentioned by Ast et ul.,' there are often a lot of sharp peaks observed in MIKE spectra which do not fit the equations given by these authors and which arise from decompositions of metastable ions in the acceleration field. These interference peaks are easily distinguished from normal signals in a MIKE spectrum by their much smaller peak width (see Fig. 2). Decompositions occurring within the accelerating region of the ion source have also been considered by Lacey and M a~d o n a l d .~ Their generalized treatment of ion fragmentations within the various regions of a mass spectrometer of conventional geometry is not directly related to MIKES. however. ~ _ _ _~ RESULTS AND DISCUSSION Considering the fragmentation(1) ions ml+ continuously decompose along their flight path through the mass spectrometer. The local point of decomposition is determined by the rate constants of reaction (1) and by instrumental parameters. Those ions m2+ which are formed within the accelerating region of the ion source will obtain a continuum of kinetic energies, given by Eqn Similarly, the electric sector voltage Ef at which these ions pass the electric sector is given by Eqn (4) derived from Eqn (2)From Eqns (3 and 4) the range of apparent masses mf and the range of the electric sector voltages can be evaluated for reaction (1) occurring in the accelerating region of the ion source. Setting f = 0 is equivalent to regarding ions m2+ generated in the ion source before acceleration, i.e. mf = m2 and Ef = E,. The other extreme, f = 1, is equivalent to observing ions m2+ formed in the first field free region, i.e. Thus, by preselecting mf values in between these extremes the fraction f of V, [Eqn (2)] at which the observed m2+ is formed is predetermined and can be calculated explicitly from Eqn ( 5 )Having determined f the corresponding E, can be calculated [Eqn (4)] and the interference peak can be recorded. This is most easily done on a mass spectrometer with 'reversed geometry' by setting the magnet current to the appropriate mf/z value and scanning E over a small region around Ef In this way any slow fragmentation reaction can be followed step by step from the ionization chamber to the 1st field free region (FFR).~ The procedure outlined above is illustrated by the reactions shown in Scheme 1. The ranges of m, and Ef values are also given in Scheme 1. Three regions of mf values can be distinguished in this case: (i) 1 4 9 3 mf 3 145, only ions b are expected to be transmitted, (ii) 145 2 mf 3 135, both ions a and ions b can be transmitted, (iii) 1 3 4 ...

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“…MIKE experiments, patterned after those of Ast et a1., 13 involving minor changes in the magnet setting, suggest that the m/z 263 ion is an artefact. Also, a corresponding ion was not present in the MIKE spectra of the deuterated analogues of 3e and 2f, namely ions 2e and 3f:…”

Section: Methodsmentioning

confidence: 99%

Study of selected ions in the ammonia desorption chemical ionization mass spectra of peracetylated gentiobiose and two isotopically labelled peracetylated gentiobioses

Peltier

Smith

MacLean

et al. 1992

Org. Mass Spectrom.

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The ammonia desorption chemical ionization (NH,-DCI) mass spectra of peracetylated gentiobiose (1) and two isotopically labelled gentiobioses (2 and 3) were examined. Compound 2 is labelled with trideuteroacetyl groups in the non-reducing moiety and 3 with trideuteroacetyl groups in the reducing moiety. It is shown that the [ M + NH, -421 + ion is not formed direct from [ M + NH,] + by loss of ketene but appears to be formed by way of a nucleophilic acyl substitution reaction resulting in a neutral species which complexes with NH,+. The disaccharides undergo cleavage at either side of the glycosidic oxygen joining the two sugar residues, a process which is accompanied by addition of H or CH,CO to afford neutral species which complex with NH,'. The structures of the ions resulting from H transfer have been inferred by comparison of their mass-analysed ion kinetic energy (MIKE) spectra with MIKE spectra of the [ M + NH,] + ions of compounds of established structure. A ring fragmentation reaction of 1,2 and 3 is reported. + NH, ' +CH3C0 / O A c / ++ NH, ' + H J NH, ' t CH3C0 Figure 1. A partial fragmentation scheme for peracetylated maltotetraose.

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Interference peaks in mass analysed ion kinetic energy spectra

Cited by 55 publications

References 13 publications

Nachweis von Fragment‐Genesen im Massenspektrometer. 5. Mitteilung Aminosäure‐Sequenzanalyse: Vergleich der DADI/MIKE‐, ‘linked scan’‐ und Kollisionsaktivierungs‐Spektrometrie an aliphatischen Aminosäuren

Nachweis von Fragment‐Genesen im Massenspektrometer. 5. Mitteilung Aminosäure‐Sequenzanalyse: Vergleich der DADI/MIKE‐, ‘linked scan’‐ und Kollisionsaktivierungs‐Spektrometrie an aliphatischen Aminosäuren

Further interference peaks in mass analysed ion kinetic energy spectra

Study of selected ions in the ammonia desorption chemical ionization mass spectra of peracetylated gentiobiose and two isotopically labelled peracetylated gentiobioses

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