A novel sample preparation and calibration approach for nanoparticle analysis using laser ablation single particle- ICP MS

Abstract

Nanoparticles find diverse applications across a wide range of fields owing to the unique physicochemical properties exhibited by materials at the nanoscale [1] [2]. Accurate characterization of nanoparticles is crucial for both material manufacturing and assessing their environmental and human health impact. For this purpose, single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) has emerged as a crucial analytical tool for nanoparticle analysis [1]. However, traditional SP-ICP-MS, designed for nanoparticles in suspension, presents challenges related to sample stability, sample introduction efficiency, and potential spectral interferences from the suspension medium. To overcome these limitations, it is possible to use solid sample analysis with laser ablation as the sampling technique [2] [3]. This method brings essential advantages to nanoparticle analysis, allowing for sizing and counting directly within a solid matrix. Moreover, it preserves embedded nanoparticles without altering their size and composition. Similar to conventional SP-ICP-MS, laser ablation SP-ICP-MS requires nanoparticle standards for signal calibration. This study focused on creating nanoparticle dispersions within polymer matrices using a spin coating method. The primary goal was to achieve a uniform distribution of isolated nanoparticles within the resulting polymer thin film, preventing particle agglomeration. The spin coating approach offers the distinct advantage of producing even and consistently thin polymer films. These films can serve as standards for signal calibration when a specified quantity of solute analyte is added, and a precise film area with a defined thickness is ablated. The investigation explored the impact of different sample preparation procedures and the effects of laser energy during the ablation process and aimed to analyze the size distributions of nanoparticles. Quadrupole ICP-MS was employed for analyzing nanoparticles consisting of a single element, while time-of-flight ICP-MS was utilized for multi-element nanoparticles. The findings from this study aim to contribute to the ongoing development of laser ablation SP- ICP-MS techniques.