Application of non-resonant laser ionization mass spectrometry for a fast isotope analysis of metal microparticles

Isotope analysis of metal microparticles was performed by adopting a laser ionization mass spectrometry with slightly defocused ablation laser beam. The analyzed sample particles were Pb, Zn, Ni and Gd2O3. The sizes of particle size were 75, 50, 10, and < 10 μm, for Pb, Zn, Ni and Gd2O3, respectively. Sample particles were loaded onto a tantalum or zirconium sheet by using a Collodion. For large-sized particles such as Pb and Zn, a single particle was loaded on the metal sheet for a laser ablation, while several particles were loaded for particles with less than 10 μm in size due to a limitation in the particle handling technique. An isotope analysis was performed by a direct laser ionization followed by a mass analysis of the loaded samples with the Collodion using a 532 nm laser. A slight defocusing of the adopted laser provided a longer time for the experiment with a single microparticle. The isotope abundances of the adopted elements were measured and the deviation from the natural abundance was calculated as less than 5-10% depending on samples used except for the minor isotopes.