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1.

001-es BibID:BIBFORM051769
Első szerző:Kuki Ákos (villamosmérnök)
Cím:Activation Energies of Fragmentations of Disaccharides by Tandem Mass Spectrometry / Ákos Kuki, Lajos Nagy, Katalin E. Szabó, Borbála Antal, Miklós Zsuga, Sándor Kéki
Dátum:2014
ISSN:1044-0305 (print) 1879-1123 (online)
Megjegyzések:A simple multiple collision model for collision induced dissociation (CID) in quadrupole was applied for the estimation of the activation energy (Eo) of the fragmentation processes for lithiated and trifluoroacetated disaccharides, such as maltose, cellobiose, isomaltose, gentiobiose and trehalose. The internal energy-dependent rate constants k(Eint) were calculated using the Rice-Ramsperger-Kassel-Marcus (RRKM) or the Rice-Ramsperger-Kassel (RRK) theory. The Eo values were estimated by fitting the calculated survival yield (SY) curves to the experimental ones. The calculated Eo values of the fragmentation processes for lithiated disaccharides were in the range of 1.4 - 1.7 eV, and were found to increase in the order trehalose < maltose < isomaltose < cellobiose < gentiobiose.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
multiple collisions
tandem mass spectrometry
collision-induced dissociation
RRK and RRKM model
disaccharides
Megjelenés:Journal Of The American Society For Mass Spectrometry 25 : 3 (2014), p. 439-443. -
További szerzők:Nagy Lajos (1979-) (vegyész) Szabó Erzsébet Katalin (1989-) (vegyész) Antal Borbála (1988-) (vegyész) Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
Pályázati támogatás:K-101850
OTKA
TÁMOP-4.2.2.A-11/1/KONV-2012-0036
TÁMOP
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DOI
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2.

001-es BibID:BIBFORM047204
Első szerző:Kuki Ákos (villamosmérnök)
Cím:Estimation of Activation Energy from the Survival Yields : Fragmentation Study of Leucine Enkephalin and Polyethers by Tandem Mass Spectrometry / Ákos Kuki, Ghazaleh Shemirani, Lajos Nagy, Borbála Antal, Miklós Zsuga, Sándor Kéki
Dátum:2013
ISSN:1044-0305
Megjegyzések:A simple collision model for multiple collisions occurring in quadrupole type massspectrometers was derived and tested with Leucine enkaphalin a common mass spectrometricstandard with well-characterized properties. Implementation of the collision model and Rice?Ramsperger?Kassel?Marcus (RRKM) algorithm into a spreadsheet software allowed a goodfitting of the calculated data to the experimental survival yield (SY) versus collision energycurve. In addition, fitting also ensured to estimate the efficiencies of the kinetic to internalenergy conversion for Leucine enkephalin in quadrupole-time-of-flight and triple quadrupoleinstruments. It was observed that the experimental SY versus collision energy curves for theLeucine enkephalin can be described by the and Rice?Ramsperger?Kassel (RRK) formalismby reducing the total degrees of freedom (DOF) to about one fifth. Furthermore, this collisionmodel with the RRK formalism was used to estimate the critical energy (Eo) of lithiatedpolyethers including polyethylene glycol (PEG), polypropylene glycol (PPG) andpolytetrahydrofurane (PTHF) with degrees of freedom similar to that of Leucine enkephalin.Applying polyethers with similar DOF provided the elimination of the effect of DOF on theunimolecular reaction rate constant. The estimated value of Eo for PEG showed a relativelygood agreement with the value calculated by high-level quantum chemical calculationsreported in the literature. Interestingly, it was also found that the Eo values for the studiedpolyethers were similar.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Doktori iskola
Fizikai-, Számítás- és Anyagtudomány
Megjelenés:Journal Of The American Society For Mass Spectrometry. - 24 : 7 (2013), p. 1064-1071. -
További szerzők:Shemirani, Ghazaleh (1983-) (vegyész) Nagy Lajos (1979-) (vegyész) Antal Borbála (1988-) (vegyész) Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
Pályázati támogatás:K-101850
OTKA
TÁMOP-4.2.2/B-10/1-2010-0024
TÁMOP
Kémiai Tudományok Doktori Iskola
TÁMOP-4.2.2.A-11/1/KONV-2012-0036
TÁMOP
TÁMOP-4.2.1/B-09/1/KONV-2010-0007
TÁMOP
Orvosi és gyógyszerészeti célra alkalmas polimerbázisú nanokompozitok előállítása
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3.

001-es BibID:BIBFORM016383
Első szerző:Kuki Ákos (villamosmérnök)
Cím:Energy-dependent collision-induced dissociation of lithiated polytetrahydrofuran : Effect of the size on the fragmentation properties / Ákos Kuki, Lajos Nagy, Antony Memboeuf, László Drahos, Károly Vékey, Miklós Zsuga, Sándor Kéki
Dátum:2010
ISSN:1044-0305
Megjegyzések:The fragmentation properties of singly and doubly lithiated polytetrahydrofuran (PTHF) were studied using energy-dependent collision-induced dissociation. The product ion spectrum of [PTHF+Li]+ showed the formation of three different series corresponding to product ions with hydroxyl, aldehyde and vinyl end-groups. Interestingly, besides these series, two additional, non-lithiated product ions C4H9O+ and C4H7+ were identified in the MS/MS spectra. The MS/MS of the doubly lithiated PTHF ([PTHF+2Li]2+) with a number of repeat units ranging from 8 to 27 showed the formation of product ions similar to those of the singly lithiated series, however, doubly lithiated product ions and product ions formed by the loss of one Li+-ion from the precursor ion also appeared with significant abundances. Analysis of the breakdown curves for the singly and doubly charged PTHF indicated that the series A ions are formed most probably together with the series B ions, while members of the series C ions appeared at significantly higher collision energies. The fragmentation properties of [PTHF+Li]+ and [PTHF+2Li]2+ were also interpreted using the survival yield method. It was found that the collision energy/voltage necessary to obtain 50% fragmentation (CV50) was dependent linearly on the number of the repeat units, i.e., on the size, or the number of degrees of freedom (DOF).
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal Of The American Society For Mass Spectrometry. - 21 : 10 (2010), p. 1753-1761. -
További szerzők:Nagy Lajos (1979-) (vegyész) Memboeuf, Antony Drahos László Vékey Károly Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
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4.

001-es BibID:BIBFORM016386
Első szerző:Kuki Ákos (villamosmérnök)
Cím:Ligand size distribution of phenanthroline-functionalized polyethylene glycol-iron(II) complexes determined by electrospray ionization mass spectrometry and computer simulation / Ákos Kuki, Miklós Nagy, Lajos Nagy, Miklós Zsuga, Sándor Kéki
Dátum:2010
ISSN:1044-0305
Megjegyzések:The complex formation in solution, and the gas-phase dissociation of a phenanthroline-terminated poly(ethylene glycol) with Fe2+ ions were investigated. The size distribution of poly(ethylene glycol)-?-monomethyl-?-5-[1,10]phenanthroline (mPEG_phen) was determined by Electrospray Ionization Mass Spectrometry (ESI-MS). Based on the measured ligand size distribution of mPEG-phen by ESI-MS, the 1:3 complex formation (Fe2+/mPEG_Phen) was computer-simulated as a pure random assembly process. The simulated distribution fits excellently to that of the complex Fe(mPEG_Phen)32+ determined from the ESI-MS intensities. In addition, the collision-induced dissociation (CID) of the Fe(mPEG_phen)32+ complex was also studied by tandem mass spectrometry (ESI-MS/MS) and by computer simulation, as well. The ESI-MS/MS intensity distribution of the Fe(mPEG_phen)22+ formed from Fe(mPEG_phen)32+ by the loss of an mPEG_phen ligand under CID conditions fits quite well to the calculated one.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal Of The American Society For Mass Spectrometry. - 21 : 9 (2010), p. 1561-1564. -
További szerzők:Nagy Miklós (1976-) (vegyész) Nagy Lajos (1979-) (vegyész) Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
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DOI
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5.

001-es BibID:BIBFORM064081
Első szerző:Nagy Lajos (vegyész)
Cím:Can Nonpolar Polyisobutylenes be Measured by Electrospray Ionization Mass Spectrometry? Anion-Attachment Proved to be an Appropriate Method / Lajos Nagy, Tibor Nagy, György Deák, Ákos Kuki, Mihály Purgel, Mijid Narmandakh, Béla Iván, Miklós Zsuga, Sándor Kéki
Dátum:2016
ISSN:1044-0305 1879-1123
Megjegyzések:Polyisobutylenes (PIBs) with different end-groups including chlorine, exoolefin,hydroxyl, and methyl prepared from aliphatic and aromatic initiators werestudied by electrospray ionization mass spectrometry (ESI-MS). Independently ofthe end-groups, presence or absence of aromatic initiator moiety, these PIB derivativeswere capable of forming adduct ions with NO3? and Cl? ions, thus allowing thedirect characterization of these compounds in the negative ion mode of ESI-MS. Toobtain [PIB + NO3]? and [PIB + Cl]? adduct ions with appreciable intensities, additionof polar solvents such as acetone, 2-propanol, or ethanol to the dichloromethanesolution of PIBs was necessary. Furthermore, increasing both the polarity (by increasingthe acetone content) and the ion-source temperature give rise to enhancedintensities for both [PIB + NO3]? and [PIB + Cl]? ions. Energy-dependent collision induced dissociation studies(CID) revealed that increasing the collision voltages resulted in the shift of the apparent molecular masses tohigher ones. CID studies also showed that dissociation of the [PIB + Cl]? ions requires higher collision energythan that of [PIB + NO3]?. In addition, Density Functional Theory calculations were performed to gain insights intothe nature of the interactions between the highly non-polar PIB chains and anions NO3? and Cl? as well as todetermine the zero-point corrected electronic energies for the formation of [PIB + NO3]? and [PIB + Cl]? adductions.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
ESI-MS
Polyisobutylenes
Nitrated adduct ions
Chlorinated adduct ions
Tandem mass spectrometry
Megjelenés:Journal Of The American Society For Mass Spectrometry. - 27 : 3 (2016), p. 432-442. -
További szerzők:Nagy Tibor (1988-) (vegyész) Deák György (1954-) (polimer kémikus) Kuki Ákos (1966-) (villamosmérnök) Purgel Mihály (1982-) (vegyész) Narmandakh, Mijid Iván Béla Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
Pályázati támogatás:TÁMOP-4.2.2.C-11/1/KONV-2012-0010
TÁMOP
K-101850
OTKA
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6.

001-es BibID:BIBFORM010304
Első szerző:Nagy Lajos (vegyész)
Cím:Dopant-Assisted Atmospheric Pressure Photoionization Mass Spectrometry of Polyisobutylene Derivatives Initiated by Mono- and Bifunctional Initiators / Lajos Nagy, Viktória Pálfi, Mijid Narmandakh, Ákos Kuki, Andrea Nyíri, Béla Iván, Miklós Zsuga, Sándor Kéki
Dátum:2009
Megjegyzések:Nine polyisobutylene (PIB) derivatives with different end groups (chlorine, vinyl, isobutenyl, 2,2-diphenylvinyl, and carboxyl) and molecular weights (1000 to 4500 g/mol), initiated by monofunctional and aromatic bifunctional initiators were studied by atmospheric pressure photoionization mass spectrometry (APPI-MS) in both the negative and the positive ion modes. Consistent with previous findings, negative ion APPI-MS revealed end-group identities through the formation of PIB adducts with chloride ions formed in situ from a chlorinated solvent (e.g., CCl4) in the presence of a dopant (toluene). In positive ion mode, considerable fragmentation of these PIB derivatives was observed, rendering end-group determinations very difficult. The Mn values obtained by APPI(-)-MS were considerably lower than those determined by SEC for PIB derivatives with Mn higher than 2000 g/mol. PIBs containing carboxyl termini can undergo collision-induced dissociation, yielding structurally important product ions. The resulting APPI-MS/MS intensities were found to reflect the "arm-length" distribution for PIBs with bifunctional aromatic moieties. In positive ion mode, [M+COCl]+ adducts were observed for PIBs with an aromatic initiator moiety. The origin of the COCl+ species is also discussed.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Polyisobutylene
APPI-MS
mass spectrometry
chloride ion attachment
Megjelenés:Journal of the American Society for Mass Spectrometry. - 20 : 12 (2009), p. 2342-2351. -
További szerzők:Pálfi Viktória Narmandakh, Mijid Kuki Ákos (1966-) (villamosmérnök) Nyíri Andrea Iván Béla Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
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