Elemental analysis by Au-nanopartciles enahnced LA-ICP-MS

Introduction A preliminary study of nanoparticles-enhanced LA-ICP-MS is presented. It represents an analytical strategy to improve the analytical performance of the LA-ICP-MS in terms of sensitivity and LOD, preserving its excellent characteristics (simplicity, rapidity, etc.), without any changes in the experimental set-up. Methods Some drops of Gold Nanoparticles (AuNPs) colloidal dispersion were deposited on the sample’s surface, the solvent evaporated before the analysis. Spherical AuNPs dispersions in aqueous citrate buffer (Sigma Aldrich Co.) or naked PLAL (Pulse Laser Ablation in Liquid) [1] AuNPs of different size were used on certified standard target (Copper, Titanium, Bronze, Brass, Silicon and Glass). Results A considerable increase of the measured signal intensity was observed in the presence of AuNPs. By analogy with results already obtained with Laser Induced Breakdown Spectroscopy [2,3], when a critical number of NPs are deposited on the target surface, the laser pulse electromagnetic field induces the collective oscillation of the conduction electrons of the NPs that in turn results in a strong enhancement of the field. The improvement is probably induced by the best quality of the nanoparticles' agglomerate generated during the laser ablation. Metallic elements show enhancement also in non-conductive matrices. Different metallic elements show different enhancement in the same matrix, as well as the same element shows different enhancement in different matrices. It should be noted the AuNPs can be completely removed after the analysis. Conclusions The existence of an improvement of sensitivity in LA-ICP-MS signal via AuNPs allows to identify and quantify elements without damaging significantly the sample's surface unlike conventional LA-ICP-MS. Novel Aspect The AuNPs allow to improve the sensitivity of LA-ICP-MS technique almost in a nondestructive mode, which can be extremely useful in many fields as forensic sciences and cultural heritage