Skip to main content
SpringerLink
Log in

The Ionization Mechanisms in Direct and Dopant-Assisted Atmospheric Pressure Photoionization and Atmospheric Pressure Laser Ionization

  • Research Article
  • Published:
Journal of The American Society for Mass Spectrometry

Abstract

A novel, gas-tight API interface for gas chromatography–mass spectrometry was used to study the ionization mechanism in direct and dopant-assisted atmospheric pressure photoionization (APPI) and atmospheric pressure laser ionization (APLI). Eight analytes (ethylbenzene, bromobenzene, naphthalene, anthracene, benzaldehyde, pyridine, quinolone, and acridine) with varying ionization energies (IEs) and proton affinities (PAs), and four common APPI dopants (toluene, acetone, anisole, and chlorobenzene) were chosen. All the studied compounds were ionized by direct APPI, forming mainly molecular ions. Addition of dopants suppressed the signal of the analytes with IEs above the IE of the dopant. For compounds with suitable IEs or Pas, the dopants increased the ionization efficiency as the analytes could be ionized through dopant-mediated gas-phase reactions, such as charge exchange, proton transfer, and other rather unexpected reactions, such as formation of [M + 77]+ in the presence of chlorobenzene. Experiments with deuterated toluene as the dopant verified that in case of proton transfer, the proton originated from the dopant instead of proton-bound solvent clusters, as in conventional open or non-tight APPI sources. In direct APLI using a 266 nm laser, a narrower range of compounds was ionized than in direct APPI, because of exceedingly high IEs or unfavorable two-photon absorption cross-sections. Introduction of dopants in the APLI system changed the ionization mechanism to similar dopant-mediated gas-phase reactions with the dopant as in APPI, which produced mainly ions of the same form as in APPI, and ionized a wider range of analytes than direct APLI.

ᅟ

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Price excludes VAT (USA)
Tax calculation will be finalised during checkout.

Instant access to the full article PDF.

Institutional subscriptions

Figure 1
Figure 2
Scheme 1
Figure 3
Figure 4
Figure 5
Figure 6

Similar content being viewed by others

References

  1. Robb, D.B., Covey, T.R., Bruins, A.P.: Atmospheric pressure photoionization: an ionisation method for liquid chromatography-mass spectrometry. Anal. Chem. 72, 3653–3659 (2000)

    Article  CAS  Google Scholar 

  2. Syage, J.A., Evans, M.D., Hanold, K.A.: Photoionization mass spectrometry. Am. Lab. 32, 24–29 (2000)

    CAS  Google Scholar 

  3. Marchi, I., Rudaz, S., Veuthey, J.-L.: Atmospheric pressure photoionization for coupling liquid-chromatography to mass spectrometry: a review. Talanta 78, 1–18 (2009)

    Article  CAS  Google Scholar 

  4. Núñez, O., Gallart-Ayala, H., Martins, C.P.B., Moyano, E., Galceran, M.T.: Atmospheric pressure photoionization mass spectrometry of fullerenes. Anal. Chem. 84, 5316–5326 (2012)

    Article  Google Scholar 

  5. Raffaelli, A., Saba, A.: Atmospheric pressure photoionization mass spectrometry. Mass Spectrom. Rev. 22, 318–331 (2003)

    Article  CAS  Google Scholar 

  6. Kersten, H., Funcke, V., Lorenz, M., Brockmann, K.J., Benter, T., O’Brien, R.: Evidence of neutral radical induced analyte ion transformations in APPI and near-VUV APLI. J. Am. Soc. Mass Spectrom. 20, 1868–1880 (2009)

    Article  CAS  Google Scholar 

  7. Klee, S., Albrecht, S., Derpmann, V., Kersten, H., Benter, T.: Generation of ion-bound solvent clusters as reactant ions in dopant-assisted APPI and APLI. Anal. Bioanal. Chem. 405, 6933–6951 (2013)

    Article  CAS  Google Scholar 

  8. Kauppila, T.J., Kuuranne, T., Meurer, E.C., Eberlin, M.N., Kotiaho, T., Kostiainen, R.: Atmospheric pressure photoionization. The ionization mechanism and the effect of the solvent on ionization of naphthalenes. Anal. Chem. 74, 5470–5479 (2002)

    Article  CAS  Google Scholar 

  9. Revelsky, I.A., Yashin, Y.S., Sobolevsky, T.G., Revelsky, A.I., Miller, B., Oriedo, V.: Electron ionization and atmospheric pressure photochemical ionization in gas chromatography–mass spectrometry analysis of amino acids. J. Mass Spectrom. 9, 497–507 (2003)

    CAS  Google Scholar 

  10. Haapala, M., Luosujärvi, L., Saarela, V., Kotiaho, T., Ketola, R.A., Franssila, S., Kostiainen, R.: Microchip for combining gas chromatography or capillary liquid chromatography with atmospheric pressure photoionization-mass spectrometry. Anal. Chem. 79, 4994–4999 (2007)

    Article  CAS  Google Scholar 

  11. Luosujärvi, L., Haapala, M., Thevis, M., Saarela, V., Franssila, S., Ketola, R.A., Kostiainen, R., Kotiaho, T.: Analysis of selective androgen receptor modulators by gas chromatography-microchip atmospheric pressure photoionization-mass spectrometry. J. Am. Soc. Mass Spectrom. 21, 310–316 (2010)

    Article  Google Scholar 

  12. Luosujärvi, L., Karikko, M.-M., Haapala, M., Saarela, V., Huhtala, S., Franssila, S., Kostiainen, R., Kotiaho, T., Kauppila, T.J.: Gas chromatography–mass spectrometry of polychlorinated biphenyls using atmospheric pressure chemical ionization and atmospheric pressure photoionization microchips. Rapid Commun. Mass Spectrom. 22, 425–431 (2008)

    Article  Google Scholar 

  13. Hintikka, L., Haapala, M., Franssila, S., Kuuranne, T., Leinonen, A., Kostiainen, R.: Feasibility of gas chromatography-microchip atmospheric pressure photoionization-mass spectrometry in analysis of anabolic steroids. J. Chromatogr. A 217, 8290–8297 (2010)

    Article  Google Scholar 

  14. Kersten, H., Derpmann, V., Barnes, I., Brockmann, K.J., O’Brien, R., Benter, T.: A novel APPI-MS setup for in situ degradation product studies of atmospherically relevant compounds: capillary atmospheric pressure photo ionization (cAPPI). J. Am. Soc. Mass Spectrom. 22, 2070–2081 (2011)

    Article  CAS  Google Scholar 

  15. Revelsky, I.A., Yashin, Y.S.: New approach to complex organic compounds mixtures analysis based on gas chromatography–atmospheric pressure photoionization-mass spectrometry. Talanta 102, 110–113 (2012)

    Article  CAS  Google Scholar 

  16. Hintikka, L., Haapala, M., Kuuranne, T., Leinonen, A., Kostiainen, R.: Analysis of anabolic steroids in urine by gas chromatography-microchip atmospheric pressure photoionization-mass spectrometry with chlorobenzene as dopant. J. Chromatogr. A 1312, 111–117 (2013)

    Article  CAS  Google Scholar 

  17. Suominen, T., Haapala, M., Takala, A., Ketola, R.A., Kostiainen, R.: Neurosteroid analysis by gas chromatography–atmospheric pressure photoionization-tandem mass spectrometry. Anal. Chim. Acta. 794, 76–81 (2013)

    Article  CAS  Google Scholar 

  18. Haapala, M., Suominen, T., Kostiainen, R.: Capillary photoionization: a high sensitivity ionization method for mass spectrometry. Anal. Chem. 85, 5715–5719 (2013)

    Article  CAS  Google Scholar 

  19. Kersten, H., Haberer, K., Kroll, K., Benter, T.: Progress in the development of a GC-APPI source with femtogram sensitivity. Proceedings of the 62nd ASMS Conference on Mass Spectrometry and Allied Topics, Baltimore, MD, 4–9 June 2014

  20. Peterson, A.C., Kersten, H., Krumwiede, D., Quarmby, S., D’Silva, K., Kroll, K., Haberer, K., Bromirski, M., Makarov, A., Benter, T.: Analytical performance of a novel, dopant-free GC-APPI source with femtogram-level sensitivity for quadrupole-Orbitrap GC/MS. Presented at the 62nd ASMS Conference on Mass Spectrometry and Allied Topics, Baltimore, MD, 15–19 June 2014

  21. Constapel, M., Schellentraeger, M., Schmitz, O.J., Gaeb, S., Brockmann, K.J., Giese, R., Benter, T.: Atmospheric-pressure laser ionization: a novel ionization method for liquid chromatography/mass spectrometry. Rapid Commun. Mass Spectrom. 19, 326–336 (2005)

    Article  CAS  Google Scholar 

  22. Schiewek, R., Schellenträger, M., Mönnikes, R., Lorenz, M., Giese, R., Brockmann, K.J., Gäb, S., Benter, T., Schmitz, O.J.: Ultrasensitive determination of polycyclic aromatic compounds with atmospheric-pressure laser ionization as an interface for GC/MS. Anal. Chem. 79, 4135–4140 (2007)

    Article  CAS  Google Scholar 

  23. Schrader, W., Panda, S.K., Brockmann, K.J., Benter, T.: Characterization of non-polar aromatic hydrocarbons in crude oil using atmospheric pressure laser ionization and Fourier transform ion cyclotron resonance mass spectrometry (APLI FT-ICR MS). Analyst 133, 867–869 (2008)

    Article  CAS  Google Scholar 

  24. Panda, S.K., Brockmann, K.-J., Benter, T., Schrader, W.: Atmospheric pressure laser ionization (APLI) coupled with Fourier transform ion cyclotron resonance mass spectrometry applied to petroleum samples analysis: comparison with electrospray ionization and atmospheric pressure photoionization methods. Rapid Commun. Mass Spectrom. 25, 2317–2326 (2011)

    Article  CAS  Google Scholar 

  25. Stader, C., Beer, F.T., Achten, C.: Environmental PAH analysis by gas chromatography-atmospheric pressure laser ionization-time-of-flight mass spectrometry (GC-APLI-MS). Anal. Bioanal. Chem. 405, 7041–7052 (2013)

    Article  CAS  Google Scholar 

  26. Dion, C.F., Bernstein, E.R.: On the low‐lying Rydberg states of azabenzenes. J. Chem. Phys. 103, 4907–4913 (1995)

    Article  CAS  Google Scholar 

  27. Tsubouchi, M., Suzuki, T.: Femtosecond photoelectron imaging on pyridine: ultrafast electronic dephasing from the S1(nπ*) state and Rydberg state energetics. J. Phys. Chem. A 107, 10897–10903 (2003)

    Article  CAS  Google Scholar 

  28. Streibel, T., Hafner, K., Mühlberger, F., Adam, T., Zimmermann, R.: Resonance-enhanced multiphoton ionization time-of-flight mass spectrometry for detection of nitrogen containing aliphatic and aromatic compounds: resonance-enhanced multiphoton ionization spectroscopic investigation and on-line analytical application. Appl. Spectrosc. 60, 72–79 (2006)

    Article  CAS  Google Scholar 

  29. Tubaro, M., Marotta, E., Seraglia, R., Traldi, P.: Atmospheric pressure photoionization mechanisms. 2. The case of benzene and toluene. Rapid Commun. Mass Spectrom. 17, 2423–2429 (2003)

    Article  CAS  Google Scholar 

  30. Robb, D.B., Blades, M.W.: Effects of solvent flow, dopant flow, and lamp current on dopant-assisted atmospheric pressure photoionization (DA-APPI) for LC-MS. Ionization via proton transfer. J. Am. Soc. Mass Spectrom. 16, 1275–1290 (2005)

    Article  CAS  Google Scholar 

  31. Tzeng, W.B., Wei, S., Castleman, A.W.: Multiphoton ionization of acetone clusters: metastable unimolecular decomposition of acetone cluster ions and the influence of solvation on intracluster ion-molecule reactions. J. Am. Chem. Soc. 111, 6035–6040 (1989)

    Article  CAS  Google Scholar 

  32. Kadi, M., Davidsson, J., Tarnovsky, A.N., Rasmusson, M., Åkesson, E.: Photodissociation of aryl halides in the gas phase studied with femtosecond pump-probe spectroscopy. Chem. Phys. Lett. 350, 93–98 (2001)

    Article  CAS  Google Scholar 

  33. Laor, U., Ludwig, P.K.: Fluorescence lifetimes of vibronic states of naphthalene vapor in the region of excitation from 3080–2150 Å. J. Chem. Phys. 54, 1054–1057 (1971)

    Article  CAS  Google Scholar 

  34. Haefliger, O.P., Zenobi, R.: Laser mass spectrometric analysis of polycyclic aromatic hydrocarbons with wide wavelength range laser multiphoton ionization spectroscopy. Anal. Chem. 70, 2660–2665 (1998)

    Article  CAS  Google Scholar 

  35. Mühlberger, F., Hafner, K., Kaesdorf, S., Ferge, T., Zimmermann, R.: Comprehensive on-line characterization of complex gas mixtures by quasi-simultaneous resonance-enhanced multiphoton ionization, vacuum-UV single-photon ionization, and electron impact ionization in a time-of-flight mass spectrometer: setup and instrument characterizatio. Anal. Chem. 76, 6753–6764 (2004)

    Article  Google Scholar 

  36. Haapala, M., Pol, J., Saarela, V., Arvola, V., Kotiaho, T., Ketola, R.A., Franssila, S., Kauppila, T.J., Kostiainen, R.: Desorption atmospheric pressure photoionization. Anal. Chem. 79, 7867–7872 (2007)

    Article  CAS  Google Scholar 

  37. Luosujärvi, L., Arvola, V., Haapala, M., Pól, J., Saarela, V., Franssila, S., Kotiaho, T., Kostiainen, R., Kauppila, T.J.: Desorption and ionization mechanisms in desorption atmospheric pressure photoionization. Anal. Chem. 80, 7460–7466 (2008)

    Article  Google Scholar 

  38. Vaikkinen, A., Kotiaho, T., Kostiainen, R., Kauppila, T.J.: Desorption atmospheric pressure photoionization with PDMS as extraction phase and sample plate material. Anal. Chim. Acta. 682, 1–8 (2010)

    Article  CAS  Google Scholar 

  39. Harrison, A.G.: Chemical Ionization Mass Spectrometry. CRC Press, Boca Raton, FL (1992)

    Google Scholar 

  40. McCollum, J., Meyerson, S.: Organic ions in gas phase. X. Decomposition of benzaldehyde under electron impact. J. Am. Chem. Soc. 85, 1739–1741 (1963)

    Article  CAS  Google Scholar 

  41. Robb, D.B., Smith, D.R., Blades, M.W.: Investigation of substituted-benzene dopants for charge exchange ionization of nonpolar compounds by atmospheric pressure photoionization. J. Am. Soc. Mass Spectrom. 19, 955–963 (2008)

    Article  CAS  Google Scholar 

  42. Brutschy, B., Eggert, J., Janes, C., Baumgärtel, H.: Nucleophilic substitution reactions in molecular clusters following photoionization. J. Phys. Chem. 95, 5041–5050 (1991)

    Article  CAS  Google Scholar 

  43. Kauppila, T.J., Kostiainen, R., Bruins, A.P.: Anisole, a new dopant for atmospheric pressure photoionization-mass spectrometry of low proton affinity, low ionization energy compounds. Rapid Commun. Mass Spectrom. 18, 808–815 (2004)

    Article  CAS  Google Scholar 

  44. Brulik, J., Simek, Z., de Voogt, P.: A new liquid chromatography-tandem mass spectrometry method using atmospheric pressure photo ionization for the simultaneous determination of azaarenes and azaarones in Dutch river sediments. J. Chromatogr. A 1294, 33–40 (2013)

    Article  CAS  Google Scholar 

  45. Lintelmann, J., França, M.H., Hübner, E., Matuschek, G.: A liquid chromatography-atmospheric pressure photoionization tandem mass spectrometric method for the determination of azaarenes in atmospheric particulate matter. J. Chromatogr. A 1217, 1636–1646 (2010)

    Article  CAS  Google Scholar 

  46. Syage, J.A.: Mechanism of [M + H] + formation in photoionization mass spectrometry. J. Am. Soc. Mass Spectrom. 15, 1521–1533 (2004)

    Article  CAS  Google Scholar 

  47. Lorenz, M., Schiewek, R., Brockmann, K.J., Schmitz, O.J., Gäb, S., Benter, T.: The distribution of ion acceptance in atmospheric pressure ion sources: spatially resolved APLI measurements. J. Am. Soc. Mass Spectrom. 19, 400–410 (2008)

    Article  CAS  Google Scholar 

  48. Kersten, H., Lorenz, M., Brockmann, K.J., Benter, T.: Evaluation of the performance of small diode pumped UV solid state (DPSS) Nd:YAG lasers as new radiation sources for atmospheric pressure laser ionization mass spectrometry (APLI-MS). J. Am. Soc. Mass Spectrom. 22, 1063–1069 (2011)

    Article  CAS  Google Scholar 

  49. Linstrom, P.J., Mallard, W.G. Eds.: NIST Chemistry WebBook, NIST Standard Reference Database Number 69, July 2001, National Institute of Standards and Technology, Gaithersburg MD, 20899. Available at: http://webbook.nist.gov. Accessed 15 June 2014

Download references

Acknowledgments

The authors acknowledge financial support by the Academy of Finland (projects 218150, 255559, and 268757), and Magnus Ehrnrooth Foundation and iGenTrax. Thermo Scientific is acknowledged for supplying the Orbitrap, the GC, and the consumables, and Morpho Detection for supplying the APPI source.

Author information

Authors and Affiliations

  1. Faculty of Pharmacy, University of Helsinki, Helsinki, 00014, Finland

    Tiina J. Kauppila

  2. Department of Physical and Theoretical Chemistry, University of Wuppertal, 42119, Wuppertal, Germany

    Hendrik Kersten & Thorsten Benter

Authors
  1. Tiina J. Kauppila
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Hendrik Kersten
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Thorsten Benter
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Tiina J. Kauppila.

Rights and permissions

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Kauppila, T.J., Kersten, H. & Benter, T. The Ionization Mechanisms in Direct and Dopant-Assisted Atmospheric Pressure Photoionization and Atmospheric Pressure Laser Ionization. J. Am. Soc. Mass Spectrom. 25, 1870–1881 (2014). https://doi.org/10.1007/s13361-014-0988-7

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1007/s13361-014-0988-7

Key words

Search

Navigation