atmospheric pressure photoionization (APPI); bisquaternary ammonium ions; dissociative recombination; fragmentation mechanisms; H atom transfer; photoelectron; radical
Abstract :
[en] A comprehensive atmospheric pressure photoionization (APPI) mass spectrometry investigation of hexamethonium bromide is reported. This bisquaternary ammonium salt is a model system for the investigation of multiply charged species and elucidation of ion formation processes. It has been used to elucidate the physico-chemical phenomenon occurring when photoionization is carried out at atmospheric pressure. First, the in-source fragmentations were studied for aqueous solutions of the salt with the photoionization lamp switched off, i.e. under thermospray conditions. It is shown that, in this mode of operation, fragmentations are minor and may be classified into two classes, namely dequaternization and charge separation, arising from the two precursors, M2+ and [M+Br]+. Second, the fragmentation patterns have been monitored in dopant-assisted APPI for different dopants (toluene, toluene-d8 anisole and hexafluorobenzene) at various amounts. At low dopant flow rates, the [M+Br]+ and M2+ ions are still observed. As the flow rate is increased, these precursor ions lose intensity and are finally suppressed for all three dopants. Comparison of toluene and toluene-d8 reveals that H atoms may be transferred from the dopant to the molecular ions, very likely mediated by the solvent. The role of the solvent (water) was also investigated by using heavy water. Apart from the thermospray fragmentations, which are also observed in APPI, several fragmentation pathways appear to be specific to the photoionization process. Photoionization efficiencies are measured by determination of the relative photoionization cross sections with respect to toluene. It is found that, when the ionization efficiencies are taken into account, the depletion of the precursors as a function of the dopant flow rates is the same for all three dopant molecules. This result shows that the precursor ions are depleted by reactions with the photoelectrons released from the dopant. Three additional mechanisms are proposed to account for this effect: electron transfer or H atom transfer from negatively charged water nanodroplets and H atom transfer from the dopant.
Disciplines :
Chemistry
Author, co-author :
Giuliani, Alexandre; CNRS-ICSN > Laboratoire de Spectrométrie de Masse
Debois, Delphine ; CNRS-ICSN > Laboratoire de spectrométrie de masse
Laprévote, Olivier; CNRS-ICSN > Laboratoire de Spectrométrie de Masse
Language :
English
Title :
Study of a bisquaternary ammonium salt by atmospheric pressure photoionization mass spectrometry
D.B. Robb, T.R. Covey and A.P. Bruins, "Atmospheric pressure photoionization: an ionization method for liquid chromatography-mass spectrometry", Anal. Chem. 72, 3653 (2000). doi: 10.1021/ac0001636
J.A. Syage and M.D. Evans, "Photoionization Mass Spectrometry - A Powerful New Tool for Drug Discovery", Spectroscopy 16, 14 (2001).
H. Moriwaki, M. Ishitake, S. Yoshikawa, H. Miyakoda and J.-F. Alary, "Determination of polycyclic aromatic hydrocarbons in sediment by liquid chromatography-atmospheric pressure photoionization-mass spectrometry", Anal. Sci. 20, 375 (2004). doi: 10.2116/analsci.20.375
T. Kauppila, T. Kuuranne, E.C. Meurer, M.N. Eberlin, T. Kotiaho and R. Kostiainen, "Atmospheric pressure photoionization mass spectrometry. Ionization mechanism and the effect of solvent on the ionization of naphthalenes", Anal. Chem. 74, 5470 (2002). doi: 10.1021/ac025659x
E.A. Straube, W. Dekant and W. Vokel, "Comparison of electrospray ionization, atmospheric pressure chemical ionization, and atmospheric pressure photoionization for the analysis of dinitropyrene and aminonitropyrene LC-MS/MS", J. Am. Soc. Mass Spectrom. 15, 1853 (2004). doi: 10.1016/j.jasms.2004.08.017
J.-P. Rauha, H. Vuorela and R. Kostiainen, " Effect of eluent on the ionization efficiency of flavonoids by ion spray, atmospheric pressure chemical ionization, and atmospheric pressure photoionization mass spectrometry", J. Mass Spectrom. 36, 1269 (2001). doi: 10.1002/jms.231
H. Keski-Hynnilä, M. Kurkela, E. Elovaara, L. Antonio, J. Magdalou, L. Luukkanen, J. Taskinen and R. Kostiainen, "Comparison of electrospray, atmospheric pressure chemical ionization, and atmospheric pressure photoionization in the identification of apomorphine, dobutamine, and entacapone phase II metabolites in biological samples", Anal. Chem. 74, 3449 (2002). doi: 10.1021/ac011239g
C. Yang and J. Henion, "Atmospheric pressure photoionization liquid chromatographic-mass spectrometric determination of idoxifene and its metabolites in human plasma", J. Chromatogr. A 970,155 (2002). doi: 10.1016/S0021-9673(02)00882-8
G. Wang, Y. Hsieh and W.A. Korfmacher, "Comparison of Atmospheric Pressure Chemical Ionization, Electrospray Ionization, and Atmospheric Pressure Photoionization for the Determination of Cyclosporin A in Rat Plasma", Anal. Chem. 77, 541 (2005). doi: 10.1021/ac040144m
J. Lembcke, U. Ceglarek, G.M. Friedler, S. Baumann, A. Leichtle and J. Thiery, "Rapid quantification of free and esterified phytosterols in human serum using APPI-LC-MS/MS", J. Lipid Res. 46,21 (2005). doi: 10.1194/jlr.C400004-JLR200
A. Delobel, F. Halgand, B. Laffranchise-Gosse, H. Snijders and O. Laprévote, "Characterization of hydrophobic peptides by atmospheric pressure photoionization-mass spectrometry and tandem mass spectrometry", Anal. Chem. 75, 5961 (2003). doi: 10.1021/ac034532k
A. Delobel, D. Touboul and O. Laprevote, "Structural characterization of phosphatidylcholines by atmospheric pressure photoionization mass spectrometry", Eur. J. Mass Spectrom. 11, 409 (2005). doi: 10.1255/ejms.760
J. Berkowitz, Photoabsorption, Photoionization and Photoelectron Spectroscopy. Academic Press, New York, USA, pp. 93-150 (1979).
J.A. Syage "Mechanism of [M+H]+ formation in photoionization mass spectrometry", J. Am. Soc. Mass Spectrom. 15, 1521 (2004). doi: 10.1016/j.jasms.2004.07.006
T.J. Kauppila, T. Kotiaho, R. Kostiainen and A.P. Bruins, "Negative ion-atmospheric pressure photoionization-mass spectrometry", J. Am. Soc. Mass Spectrom. 15, 203 (2004). doi: 10.1016/j.jasms.2003.10.012
E. Basso, E. Marotta, R. Seraglia, M. Tubaro and P. Traldi, "On the formation of negative ions in atmospheric pressure photoionization conditions", J. Mass Spectrom. 38, 1113 (2003). doi: 10.1002/jms.528
R. Balog, J. Langer, S. Gohlke, M. Stano, H. Abdoul-Carime and E. Illenberger, "Low energy electron driven reactions in free and bound molecules: from unimolecular processes in the gas phase to complex reactions in a condensed environment", Int. J. Mass Spectrom. 233, 267 (2004). doi: 10.1016/j.ijms.2003.12.030
T.M. Ryan, R.J. Day and R.G. Cooks, "Secondary ion mass spectra of diquaternary ammonium salts", Anal. Chem. 52, 2054 (1980). doi: 10.1021/ac50063a014
V.A. Pashynska, M.V. Kosevich, A. Gömöry, O.V. Vashchenko and L.N. Lisetski, "Mechanistic investigation of the interaction between bisquaternary antimicrobial agents and phospholipids by liquid secondary ion mass spectrometry and differential scanning calorimetry", Rapid Commun. Mass Spectrom. 16, 1706 (2002). doi: 10.1002/rcm.771
V.A. Pashynska, M.V. Kosevich, A. Gömöry, Z. Szilàgyi, K. Vékey and S.G. Stepanian, "On the stability of the organic dication of the bisquaternary ammonium salt decamethoxinum under liquid secondary ion mass spectrometry", Rapid Commun. Mass Spectrom. 19, 785 (2005). doi: 10.1002/rcm.1846
K. Vékey, "Multiply charged ions", Mass Spectrom. Rev. 14, 195 (1995). doi: 10.1002/mas.1280140304
J.H. Veith, "Mass spectrometry of ammonium and iminium salts", Mass Spectrom. Rev. 2, 419 (1983). doi: 10.1002/mas.1280020402
D.A. Brent, D.J. Rouse Martin, M.C. Sammons and M.M. Bursey, "Field desorption mass spectrometry quaternary ammonium salts", Tetrahedron Lett. 42, 4127 (1973). doi: 10.1016/S0040-4039(01)87129-X
NIST Chemistry WebBook, NIST Standard Reference Database Number 69, Ed by W.G. Mallard and P.J. Linstrom. National Institute of Standards and Technology: Gaithersburg, MD, 20899, USA, http://webbook.nist.gov (2003).
S. Mendoca, W.E. Wentworth, E.C.M. Chen, and S.D. Stearns, "Relative responses of various classes of compounds using a pulsed discharge helium photoionization detector experimental determination and theoretical calculations", J. Chromatogr. A 749, 131 (1996). doi: 10.1016/0021-9673(96) 00527-4
G. Gremaud, W.E. Wentworth, A. Zlatkis, R. Swatloski, E.C.M. Chen and S.D. Stearns, "Windowless pulsed-discharge photoionization detector application to qualitative analysis of volatile organic compounds", J. Chromatogr. A 724, 235 (1996). doi: 10.1016/0021-9673(95)00921-3
W.E. Wentworth, S. Watanesk, N. Helias, R. Swatloski, E.C.M. Chen and S.D. Stearns, "Experimental and theoretical relative response factors for a pulsed discharge krypton photoionization detector", J. Chromatogr. A 749, 149 (1996). doi: 10.1016/0021-9673(96)00473-6
O.P. Balaj, C.-K. Siu, I. Balteanu, M.K. Beyer and V.E. Bondybey, "Free electrons, the simplest radicals of them all: chemistry of aqueous electrons as studied by mass spectrometry", Int. J. Mass Spectrom. 238, 65 (2004). doi: 10.1016/j.ijms.2004.08.006
S.A. Shaffer, M. Sadilek and F. Turecek, "Hypervalent Ammonium Radicals. Effects of Alkyl Groups and Aromatic Substituents", J. Org. Chem. 61, 5234 (1996). doi: 10.1021/jo960320u
S. Beranova and C. Wesdemiotis, "The unimolecular chemistry of quaternary ammonium ions and their neutral counterparts", Int. J. Mass Spectrom. Ion Proc. 134, 83 (1994). doi: 10.1016/0168-1176(94)03972-0
O.P. Balaj, I. Balteanu, B.S. Fox-Beyer, M.K. Beyer and V.E. Bondybey, "Addition of a hydrogen atom to acetonitrile by hydrated electrons in nanodroplets", Angew. Chem. Int. Ed. 42, 5516 (2003). doi: 10.1002/anie.200351953
R.A. Zubarev, "Reactions of polypeptide ions with electrons in the gas phase", Mass Spectrom. Rev. 22, 57 (2003). doi: 10.1002/mas.10042
J.E. Syka, J.J. Coon, M.J. Schroeder, J. Shabanowitz and D.F. Hunt, "Peptide and protein sequence analysis by electron transfer dissociation mass spectrometry", Proc. Natl. Acad. Sci. 101, 9528 (2004). doi: 10.1073/pnas.0402700101
M. Takayama, "In-source decay characteristic of peptides in matrix-assisted laser desorption/ionization time-of-flight mass spectrometry", J. Am. Soc. Mass Spectrom. 12, 420 (2001). doi: 10.1016/S1044-0305(01)00218-5
T. Köcher, Å. Engström and R. Zubarev, "Fragmentation of peptides in MALDI in-source decay mediated by hydrogen radical", Anal. Chem. 77, 172 (2005). doi: 10.1021/ac0489115