Selected applications of mass spectrometry


                                            Ravi Mawale

Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5/A14, 625 00 Brno, Czech
                                             Republic


                       PhD thesis supervisor: Prof. RNDr. Josef Havel DrSc.


Mass spectrometry has extensive applications in biology, chemistry, physics, medicine, etc. Use of
mass spectrometry for the analysis of organic, inorganic as well as biochemical samples is well
known. Several mass spectrometers with advanced techniques are commercially available.

   The aim of my Thesis work was to study the use of laser desorption ionization quadrupole ion
trap time-of-flight mass spectrometry (LDI QIT TOFMS) for the generation of clusters from various
precursors such as nanomaterials, nanocomposites, chalcogenide glasses, etc.

   (i) An approach for the preparation of AgTe and AuAgTe nanocomposites was developed and found
suitable for the generation of several novel Ag[m]Te[n]^+/- and Au[p]Ag[q]Te[r]^+/- clusters [1,
2].

   (ii) In paper [3] the unknown structure of AgAsS[2] glass was resolved. LDI shows the formation
of 3 unary, 38 binary (As[n]S[x], Ag[m]S[x]), and 98 ternary (Ag[m]As[n]S[x]) clusters. However,
the main finding was that the silver-rich grains are formed yielding clusters Ag[34]AsS[18]^+,
Ag[32]AsS[18]^-, etc. for example.

   (iii) The paper [4] includes a novel approach for the synthesis of giant gold nano-flowers and
it was discovered that they are alloyed with iron. Formation of Au[m]Fe[n]^+/– (m = 1 –35; n = 1
–3) clusters was described.

   (iv) Concluding, LDI with TOF MS detection was shown to be a useful technique for the generation
of clusters. The knowledge of the clusters stoichiometry is helpful to resolve the structures of
the various materials. Thanks to the sensitivity of these MS techniques, the detection of low
amount of alloyed iron in gold nanomaterial was possible.

References

[1] Ravi Mawale, Filippo Amato, Milan Alberti and Josef Havel. Generation of new AgmTen clusters
via laser ablation synthesis using Ag‐Te nano‐composite as precursor. Quadrupole ion trap
time‐of‐flight mass spectrometry. Rapid Commun. Mass Spectrom. 2014, 28, 2753–2758.

[2] Ravi Mawale, Filippo Amato, Milan Alberti and Josef Havel. Generation AgpAuqTer clusters via
laser ablation synthesis using novel Ag-Au-Te nano-composite as precursor. Laser desorption
ionization with quadrupole ion trap time-of-flight mass spectrometry. Rapid Commun. Mass Spectrom.
2014, 28, 1601–1608.

[3] Ravi Mawale, Milan Alberti, Zhang Bo, Max Fraenkl, Tomas Wagner, Josef Havel. The structure
elucidation of AgAsS[2] glass by the analysis of clusters formed during Laser Desorption Ionisation
applying QIT time-of-flight mass spectrometry. Rapid Commun. Mass Spectrom. 2016, 30, 594–602.

[4] Ravi Mawale, Mayuri Vilas Ausekar, David Pavliňák, Oleksandr Galmiz, Pavel Kubáček, Josef
Havel.  Laser Desorption Ionization Quadrupole Ion Trap Time-of-Flight Mass Spectrometry of
Au[m]Fe[n]^+/– Clusters Generated from Gold-Iron Nanoparticles and their Giant Nanoflowers.
Electrochemical and/or Plasma Assisted Synthesis.J. Am. Soc. Mass Spectrom. 2017, 28, 215-223.