Feasibility of nanoparticles enhanced laser ablation inductively coupled plasma mass spectrometry

conference proceedings

English

Elemental analysis by laser ablation (LA) spectrometry (i.e., laser ablation inductively coupled plasma mass or optical emission spectrometer (ICP-MS or ICP-OES) or laser-induced breakdown spectroscopy (LIBS)) has now become one of the most popular methods for direct solid sample analysis. The first phenomenon is in all cases (LA-ICP and LIBS) the production of microplasma at the sample surface. Production and evolution of this plasma to produce particles transported into the ICP for LA-ICP, or optical emission and cooling of this plasma to produce analytical information for LIBS are functions of laser and sample parameters. Numerous modifications have been developed to improve sensitivity and limits of detection (LOD) during last four decades. The most recent method is Nanoparticles Enhanced Laser-Induced Breakdown Spectroscopy (NELIBS), where the application of nanoparticles (NPs) on surface of sample is used to improve the sensitivity of LIBS analyses without changing the classical set-up. The desire for signal enhancement leads us to the use of NPs also in the field of ICP-MS. Although NPs are nowadays routinely analysed with LA-ICP-MS (so NPs are analyte), their effects on the ablation of the sample surface have not been investigated yet. The influence of nanoparticles (NPs) on the measured signal at Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) was studied in this work. Drops containing Ag, Au 20 and 40 nm nanoparticles were freely dried onto the sample surface with different matrices. The samples were ablated by one pulse per spot on the NPs drop area and clean surface to create signal intensity maps of selected elements. The signal enhancement of isotopes was observed only for metal samples (aluminium alloys and brass), where enhancement exceeded even two orders of magnitude in the ring of high NPs concentration in the drop. Crater profilometric inspection revealed a more uniform material re-arrangement leading to smoother craters with NPs but not any higher ablation rate. 3-sigma limits of detection were lowered by one order of magnitude for the minor elements in the presence of NPs. These results depend only on the NPs surface concentration but not on the material or size of NPs. Electron microprobe study of the ablation aerosol showed that other sample aerosol particles were settled on NPs cores. This could indicate why there was consequently a better evaporation and ionization efficiency in ICP although the exact mechanism was still behind the scope of this work.

nanoparticles; laser ablation; inductively coupled plasma mass spectrometry

SALAJKOVÁ, Z.; HOLÁ, M.; HRDLIČKA, A.; POŘÍZKA, P.; NOVOTNÝ, K.; ČELKO, L.; ŠPERKA, P.; PROCHAZKA, D.; NOVOTNÝ, J.; MODLITBOVÁ, P.; KANICKÝ, V.; KAISER, J.

26. 6. 2018

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