Effect of nanoparticle presence on aerosol formation during Nanoparticle-Enhanced Laser Ablation Inductively Coupled Plasma Mass Spectrometry

The changes in aerosol physical properties were studied by applying Nanoparticle-Enhanced Laser Ablation Inductively Coupled Plasma Mass Spectrometry (NE-LA-ICP-MS). This approach was compared to conventional LA-ICP-MS method. Analyte signal enhancement was related to particle number concentration of aerosol for three sizes of Au nanoparticles (NPs) applied on the metal sample surface in form of droplets. The dependence of the number of generated particles on the laser fluence in the range from 0.5 to 10 J cm-2 was studied. A different shape of particle size distribution (PSD) of NE-LA-ICP-MS and LA-ICP-MS aerosol was determined. The aerosol structure was additionally studied on filters using scanning electron microscopy (SEM). Comparing to LA-ICP-MS, NE-LA-ICP-MS produced a larger proportion of small particles (< 30 nm), and was approaching the ideal monodisperse aerosol that is evaporated in ICP with a high efficiency. The measurements proved that NPs on the sample surface could influence the evaporation, condensation and coagulation process in aerosol formation as well as the signal of analytes in ICP-MS.