Isotopic analysis of metallic and coated microparticles by laser ablation time-of-flight mass spectrometry (LA-TOF-MS)

A laser ablation time of flight mass spectrometry (LA-TOF-MS) technique was applied to the isotopic analysis of variety of microparticles. Sample with only two Gd2O3 particles with ~ 10 μm in diameter, the mixed particles composed of Gd2O3, Ni, and Pd, and silica particles coated with few tens of ng of Gd have been analyzed. The ablation of particles was achieved by a second harmonic of a Nd:YAG laser, 532 nm with loading these particles onto various metal matrices such as Ta, Zn, and Cu. Isotopic analysis for adopted sample was successfully carried out with good mass resolution. The loaded two small sized particles (~ 10 μm) were analyzed with reasonable isotopic ratios for enough time to observe the ion signal by the 10 Hz laser. In the case of coated particle, isotopic abundances of Gd (~ 50 ng/particle) were observed and the measured isotopic ratio reasonably agreed to the natural abundance of Gd. As far as the sample loading plates (matrix) are concerned, Ta and Cu plates showed more improved detection sensitivity and mass resolution. Direct analysis of swiped-mixed metal particles onto the cotton textile shows the possibility for an application of environmental sample analysis in nuclear safeguards.