The Influence of MS Imaging Parameters on UV-MALDI Desorption and Ion Yield

  • Kenneth N. Robinson
  • Rory T. StevenEmail author
  • Alan M. Race
  • Josephine BunchEmail author
Research Article


Ultraviolet matrix-assisted laser desorption/ionization mass spectrometry imaging (UV-MALDI MSI) is a widely used technique for imaging molecular distributions within biological systems. While much work exists concerning desorption in UV-MALDI MS, the effects of commonly varied parameters for imaging applications (repetition rate, use of continuous raster mode and raster speed), which determine spatial resolution and limits of detection for the technique, remain largely unknown. We use multiple surface characterization modalities to obtain quantitative measurements of material desorption and analyte ion yield in thin film model systems of two matrix compounds, arising from different UV-MALDI MSI sampling conditions. Observed changes in resulting ablation feature point to matrix-dependent spatial resolution and laser-induced matrix modification effects. Analyte ion yields of 10−9 to 10−6 are observed. Complex changes in ion yield, between spot and raster sampling and arising from varied laser repetition rate and raster speed, are observed.

Graphical Abstract


MALDI MSI Ionization Desorption 



The authors would like to thank Steve Pringle (Waters) for assistance in determination of Synapt ion transmission efficiencies, Wenjuan Sun (NPL) for providing access and training for the CLSM, Charles Clifford (NPL) for AFM access and training, and Ken Mingard (NPL) for providing access to SEM. Funding for the work presented here was provided through the AIMS HIGHER project as part of the NPL strategic research program.

Supplementary material

13361_2019_2193_MOESM1_ESM.docx (371 kb)
ESM 1 (DOCX 370 kb)


  1. 1.
    Greer, T., Sturm, R., Li, L.: Mass spectrometry imaging for drugs and metabolites. J. Proteome. 74, 2617–2631 (2011)CrossRefGoogle Scholar
  2. 2.
    Bonk, T., Humeny, A.: MALDI-TOF-MS analysis of protein and DNA. Neuroscientist. 7, 6–12 (2001)CrossRefGoogle Scholar
  3. 3.
    Li, L.: Overview of MS and MALDI MS for polymer analysis. In: Maldi mass spectrometry for synthetic polymer analysis, pp. 1–8. John Wiley & Sons, Inc., Hoboken (2009)CrossRefGoogle Scholar
  4. 4.
    Amstalden van Hove, E.R., Smith, D.F., Heeren, R.M.A.: A concise review of mass spectrometry imaging. J. Chromatogr. A. 1217, 3946–3954 (2010)CrossRefGoogle Scholar
  5. 5.
    Balluff, B., Schöne, C., Höfler, H., Walch, A.: MALDI imaging mass spectrometry for direct tissue analysis: technological advancements and recent applications. Histochem. Cell Biol. 136, 227–244 (2011)CrossRefGoogle Scholar
  6. 6.
    Castellino, S., Groseclose, M.R., Wagner, D.: MALDI imaging mass spectrometry: bridging biology and chemistry in drug development. Bioanalysis. 3, 2427–2441 (2011)CrossRefGoogle Scholar
  7. 7.
    Dreisewerd, K.: The desorption process in MALDI. Chem. Rev. 103, 395–426 (2003)CrossRefGoogle Scholar
  8. 8.
    Niehaus, M., Soltwisch, J.: New insights into mechanisms of material ejection in MALDI mass spectrometry for a wide range of spot sizes. Sci. Rep. 8, 7755 (2018)CrossRefGoogle Scholar
  9. 9.
    Knochenmuss, R., Zhigilei, L.V.: Molecular dynamics simulations of MALDI: laser fluence and pulse width dependence of plume characteristics and consequences formatrix and analyte ionization. J. Mass Spectrom. 45, 333–346 (2010)Google Scholar
  10. 10.
    Soltwisch, J., Jaskolla, T.W., Dreisewerd, K.: Color matters—material ejection and ion yields in UV-MALDI mass spectrometry as a function of laser wavelength and laser fluence. J. Am. Soc. Mass Spectrom. 24, 1477–1488 (2013)CrossRefGoogle Scholar
  11. 11.
    Phipps, C.: Laser ablation and its applications. Springer US, Boston (2007)CrossRefGoogle Scholar
  12. 12.
    Sadeghi, M., Vertes, A.: Crystallite size dependence of volatilization in matrix-assisted laser desorption ionization. Appl. Surf. Sci. 127–129, 226–234 (1998)CrossRefGoogle Scholar
  13. 13.
    Puretzky, A.A., Geohegan, D.B.: LIF imaging and gas-phase diagnostics of laser desorbed MALDI-matrix plumes. Appl. Surf. Sci. 127–129, 248–254 (1998)CrossRefGoogle Scholar
  14. 14.
    Rohlfing, A., Leisner, A., Hillenkamp, F., Dreisewerd, K.: Investigation of the desorption process in UV matrix-assisted laser desorption/ionization with a liquid 3-nitrobenzyl alcohol matrix by photoacoustic analysis, fast-flash imaging, and UV-laser postionization. J. Phys. Chem. C. 114, 5367–5381 (2010)CrossRefGoogle Scholar
  15. 15.
    Schmitz, T.A., Koch, J., Günther, D., Zenobi, R.: Early plume and shock wave dynamics in atmospheric-pressure ultraviolet-laser ablation of different matrix-assisted laser ablation matrices. J. Appl. Phys. 109, 123106 (2011)CrossRefGoogle Scholar
  16. 16.
    Boekelmann, V., Spengler, B., Kaufmann, R.: Dynamical parameters of ion ejection and ion formation in matrix-assisted laser desorption/ionization. Eur. Mass Spectrom. 1, 81–93 (1995)CrossRefGoogle Scholar
  17. 17.
    Ellis, S.R., Soltwisch, J., Heeren, R.M.A.: Time-resolved imaging of the MALDI linear-TOF ion cloud: direct visualization and exploitation of ion optical phenomena using a position- and time-sensitive detector. J. Am. Soc. Mass Spectrom. 25, 809–819 (2014)CrossRefGoogle Scholar
  18. 18.
    Strupat, K., Karas, M., Hillenkamp, F.: 2,5-Dihydroxybenzoic acid: a new matrix for laser desorption—ionization mass spectrometry. Int. J. Mass Spectrom. Ion Process. 111, 89–102 (1991)CrossRefGoogle Scholar
  19. 19.
    Westman, A., Huth-Fehre, T., Demirev, P., Sundqvist, B.U.R.: Sample morphology effects in matrix-assisted laser desorption/ionization mass spectrometry of proteins. J. Mass Spectrom. 30, 206–211 (1995)CrossRefGoogle Scholar
  20. 20.
    Fournier, I., Beavis, R.C., Blais, J.C., Tabet, J.C., Bolbach, G.: Hysteresis effects observed in MALDI using oriented, protein-doped matrix crystals. Int. J. Mass Spectrom. Ion Process. 169–170, 19–29 (1997)CrossRefGoogle Scholar
  21. 21.
    Kampmeier, J., Dreisewerd, K., Schürenberg, M., Strupat, K.: Investigations of 2,5-DHB and succinic acid as matrices for IR and UV MALDI. Part: I UV and IR laser ablation in the MALDI process. Int. J. Mass Spectrom. Ion Process. 169–170, 31–41 (1997)CrossRefGoogle Scholar
  22. 22.
    Wiegelmann, M., Soltwisch, J., Jaskolla, T.W., Dreisewerd, K.: Matching the laser wavelength to the absorption properties of matrices increases the ion yield in UV-MALDI mass spectrometry. Anal. Bioanal. Chem. 405, 6925–6932 (2013)CrossRefGoogle Scholar
  23. 23.
    Fournier, I., Tabet, J., Bolbach, G.: Irradiation effects in MALDI and surface modifications. Int. J. Mass Spectrom. 219, 515–523 (2002)CrossRefGoogle Scholar
  24. 24.
    Fournier, I., Marinach, C., Tabet, J.C., Bolbach, G.: Irradiation effects in MALDI, ablation, ion production, and surface modifications. Part II: 2,5-dihydroxybenzoic acid monocrystals. J. Am. Soc. Mass Spectrom. 14, 893–899 (2003)CrossRefGoogle Scholar
  25. 25.
    Spengler, B., Hubert, M.: Scanning microprobe matrix-assisted laser desorption ionization (SMALDI) mass spectrometry: instrumentation for sub-micrometer resolved LDI and MALDI surface analysis. J. Am. Soc. Mass Spectrom. 13, 735–748 (2002)CrossRefGoogle Scholar
  26. 26.
    Moon, J.H., Shin, Y.S., Bae, Y.J., Kim, M.S.: Ion yields for some salts in MALDI: mechanism for the gas-phase ion formation from preformed ions. J. Am. Soc. Mass Spectrom. 23, 162–170 (2012)CrossRefGoogle Scholar
  27. 27.
    Bae, Y.J., Shin, Y.S., Moon, J.H., Kim, M.S.: Degree of ionization in MALDI of peptides: thermal explanation for the gas-phase ion formation. J. Am. Soc. Mass Spectrom. 23, 1326–1335 (2012)CrossRefGoogle Scholar
  28. 28.
    Tsai, M.T., Lee, S., Lu, I.C., Chu, K.Y., Liang, C.W., Lee, C.H., Lee, Y.T., Ni, C.K.: Ion-to-neutral ratio of 2,5-dihydroxybenzoic acid in matrix-assisted laser desorption/ionization. Rapid Commun. Mass Spectrom. 27, 955–963 (2013)CrossRefGoogle Scholar
  29. 29.
    Ahn, S.H., Park, K.M., Bae, Y.J., Kim, M.S.: Quantitative reproducibility of mass spectra in matrix-assisted laser desorption ionization and unraveling of the mechanism for gas-phase peptide ion formation. J. Mass Spectrom. 48, 299–305 (2013)CrossRefGoogle Scholar
  30. 30.
    Bae, Y.J., Park, K.M., Kim, M.S.: Reproducibility of temperature-selected mass spectra in matrix-assisted laser desorption ionization of peptides. Anal. Chem. 84, 7107–7111 (2012)Google Scholar
  31. 31.
    Bae, Y.J., Choe, J.C., Moon, J.H., Kim, M.S.: Why do the abundances of ions generated by MALDI look thermally determined? J. Am. Soc. Mass Spectrom. 24, 1807–1815 (2013)CrossRefGoogle Scholar
  32. 32.
    Knochenmuss, R.: MALDI ionization mechanisms: the coupled photophysical and chemical dynamics model correctly predicts ‘temperature’-selected spectra. J. Mass Spectrom. 48, 998–1004 (2013)CrossRefGoogle Scholar
  33. 33.
    Chu, K.Y., Lee, S., Tsai, M.T., Lu, I.C., Dyakov, Y.A., Lai, Y.H., Lee, Y.T., Ni, C.K.: Thermal proton transfer reactions in ultraviolet matrix-assisted laser desorption/ionization. J. Am. Soc. Mass Spectrom. 25, 310–318 (2014)CrossRefGoogle Scholar
  34. 34.
    Knochenmuss, R.: Energetics and kinetics of thermal ionization models of MALDI. J. Am. Soc. Mass Spectrom. 25, 1521–1527 (2014)CrossRefGoogle Scholar
  35. 35.
    Lu, I.-C., Chu, K.Y., Lin, C.-Y., Wu, S.-Y., Dyakov, Y.a., Chen, J.-L., Gray-Weale, A., Lee, Y.-T., Ni, C.-K.: Ion-to-neutral ratios and thermal proton transfer in matrix-assisted laser desorption/ionization. J. Am. Soc. Mass Spectrom. 26, 1242–1251 (2015)CrossRefGoogle Scholar
  36. 36.
    Knochenmuss, R.: Ion yields in the coupled chemical and physical dynamics model of matrix-assisted laser desorption/ionization. J. Am. Soc. Mass Spectrom. 26, 1645–1648 (2015)CrossRefGoogle Scholar
  37. 37.
    Knochenmuss, R.: The coupled chemical and physical dynamics model of MALDI. Annu. Rev. Anal. Chem. 9, 365–385 (2016)CrossRefGoogle Scholar
  38. 38.
    Dreisewerd, K., Schürenberg, M., Karas, M., Hillenkamp, F.: Matrix-assisted laser desorption/ionization with nitrogen lasers of different pulse widths. Int. J. Mass Spectrom. Ion Process. 154, 171–178 (1996)CrossRefGoogle Scholar
  39. 39.
    Liang, S.-P., Lu, I.-C., Tsai, S.-T., Chen, J.-L., Lee, Y.T., Ni, C.-K.: Laser pulse width dependence and ionization mechanism of matrix-assisted laser desorption/ionization. J. Am. Soc. Mass Spectrom. 28, 2235–2245 (2017)CrossRefGoogle Scholar
  40. 40.
    Spraggins, J.M., Caprioli, R.M.: High-speed MALDI-TOF imaging mass spectrometry: rapid ion image acquisition and considerations for next generation instrumentation. J. Am. Soc. Mass Spectrom. 22, 1022–1031 (2011)CrossRefGoogle Scholar
  41. 41.
    Steven, R.T., Dexter, A., Bunch, J.: Investigating MALDI MSI parameters (part 1) – a systematic survey of the effects of repetition rates up to 20kHz in continuous raster mode. Methods. 104, 101–110 (2016)Google Scholar
  42. 42.
    Wiegelmann, M., Dreisewerd, K., Soltwisch, J.: Influence of the laser spot size, focal beam profile, and tissue type on the lipid signals obtained by MALDI-MS imaging in oversampling mode. J. Am. Soc. Mass Spectrom. 27, 1952–1964 (2016)CrossRefGoogle Scholar
  43. 43.
    Niehaus, M., Schnapp, A., Koch, A., Soltwisch, J., Dreisewerd, K.: New insights into the wavelength dependence of MALDI mass spectrometry. Anal. Chem. 89, 7734–7741 (2017)CrossRefGoogle Scholar
  44. 44.
    Steven, R.T., Palmer, A.D., Bunch, J.: Fluorometric beam profiling of UV MALDI lasers. J. Am. Soc. Mass Spectrom. 24, 1146–1152 (2013)CrossRefGoogle Scholar
  45. 45.
    Nečas, D., Klapetek, P.: Gwyddion: an open-source software for SPM data analysis. Open Phys. 10, 181–188 (2012)Google Scholar
  46. 46.
    Race, A.M., Styles, I.B., Bunch, J.: Inclusive sharing of mass spectrometry imaging data requires a converter for all. J. Proteome. 75, 5111–5112 (2012)CrossRefGoogle Scholar
  47. 47.
    Race, A.M., Palmer, A.D., Dexter, A., Steven, R.T., Styles, I.B., Bunch, J.: SpectralAnalysis: software for the masses. Anal. Chem. 88, 9451–9458 (2016)CrossRefGoogle Scholar
  48. 48.
    Jaskolla, T.W., Karas, M., Roth, U., Steinert, K., Menzel, C., Reihs, K.: Comparison between vacuum sublimed matrices and conventional dried droplet preparation in MALDI-TOF mass spectrometry. J. Am. Soc. Mass Spectrom. 20, 1104–1114 (2009)CrossRefGoogle Scholar
  49. 49.
    Cleveland, J.P., Anczykowski, B., Schmid, A.E., Elings, V.B.: Energy dissipation in tapping-mode atomic force microscopy. Appl. Phys. Lett. 72, 2613–2615 (1998)CrossRefGoogle Scholar
  50. 50.
    Robinson, K.N., Steven, R.T., Bunch, J.: Matrix optical absorption in UV-MALDI MS. J. Am. Soc. Mass Spectrom. 29, 501–511 (2018)CrossRefGoogle Scholar
  51. 51.
    Westmacott, G., Ens, W., Hillenkamp, F., Dreisewerd, K., Schürenberg, M.: The influence of laser fluence on ion yield in matrix-assisted laser desorption ionization mass spectrometry. Int. J. Mass Spectrom. 221, 67–81 (2002)CrossRefGoogle Scholar
  52. 52.
    Qiao, H., Spicer, V., Ens, W.: The effect of laser profile, fluence, and spot size on sensitivity in orthogonal-injection matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Rapid Commun. Mass Spectrom. 22, 2779–2790 (2008)CrossRefGoogle Scholar
  53. 53.
    Steven, R.T., Race, A.M., Bunch, J.: Probing the relationship between detected ion intensity, laser fluence, and beam profile in thin film and tissue in MALDI MSI. J. Am. Soc. Mass Spectrom. 27, 1419–1428 (2016)CrossRefGoogle Scholar
  54. 54.
    Zhigilei, L.V., Garrison, B.J.: Microscopic mechanisms of laser ablation of organic solids in the thermal and stress confinement irradiation regimes. J. Appl. Phys. 88, 1281–1298 (2000)CrossRefGoogle Scholar
  55. 55.
    Jackson, S.N., Mishra, S., Murray, K.K., Jackson, S.N., Mishra, S., Murray, K.K.: Characterization of coarse particles formed by laser ablation of MALDI matrixes. J. Phys. Chem. B. 107, 13106–13110 (2003)Google Scholar
  56. 56.
    Westman, A., Huth-Fehre, T., Demirev, P., Bielawski, J., Medina, N., Sundqvist, B.U.R., Karas, M.: Matrix-assisted laser desorption/ionization: dependence of the ion yield on the laser beam incidence angle. Rapid Commun. Mass Spectrom. 8, 388–393 (1994)CrossRefGoogle Scholar
  57. 57.
    Schürenberg, M., Dreisewerd, K., Kamanabrou, S., Hillenkamp, F.: Influence of the sample temperature on the desorption of matrix molecules and ions in matrix-assisted laser desorption ionization. Int. J. Mass Spectrom. Ion Process. 172, 89–94 (1998)CrossRefGoogle Scholar
  58. 58.
    Allwood, D.a., Dreyfus, R.W., Perera, I.K., Dyer, P.E.: UV optical absorption of matrices used for matrix-assisted laser desorption/ionization. Rapid Commun. Mass Spectrom. 10, 1575–1578 (1996)CrossRefGoogle Scholar
  59. 59.
    Koubenakis, A., Frankevich, V., Zhang, J., Zenobi, R.: Time-resolved surface temperature measurement of MALDI matrices under pulsed UV laser irradiation. J. Phys. Chem. A. 108, 2405–2410 (2004)CrossRefGoogle Scholar
  60. 60.
    Mesaros, M., Tarzi, O.I., Erra-Balsells, R., Bilmes, G.M.: The photophysics of some UV-MALDI matrices studied by using spectroscopic, photoacoustic and luminescence techniques. Chem. Phys. Lett. 426, 334–340 (2006)CrossRefGoogle Scholar
  61. 61.
    Tarzi, O.I., Nonami, H., Erra-Balsells, R.: The effect of temperature on the stability of compounds used as UV-MALDI-MS matrix: 2,5-dihydroxybenzoic acid, 2,4,6-trihydroxyacetophenone, α-cyano-4-hydroxycinnamic acid, 3,5-dimethoxy-4-hydroxycinnamic acid, nor-harmane and harmane. J. Mass Spectrom. 44, 260–277 (2009)CrossRefGoogle Scholar
  62. 62.
    Setz, P.D., Knochenmuss, R.: Exciton mobility and trapping in a MALDI matrix. J. Phys. Chem. A. 109, 4030–4037 (2005)CrossRefGoogle Scholar
  63. 63.
    Soltwisch, J., Jaskolla, T.W., Hillenkamp, F., Karas, M., Dreisewerd, K.: Ion yields in UV-MALDI mass spectrometry as a function of excitation laser wavelength and optical and physico-chemical properties of classical and halogen-substituted MALDI matrixes. Anal. Chem. 84, 6567–6576 (2012)CrossRefGoogle Scholar

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© American Society for Mass Spectrometry 2019

Authors and Affiliations

  1. 1.National Centre of Excellence in Mass Spectrometry Imaging (NiCE-MSI)National Physical LaboratoryTeddingtonUK
  2. 2.Advanced Materials and Healthcare Technologies Division (AMHT)University of NottinghamNottinghamUK
  3. 3.Department of Surgery and Cancer, Faculty of MedicineImperial College LondonLondonUK

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