Micro- and Nano-Particle Characterization via Glow Discharge Spectrometry: Fast Direct-Solid Analysis Down to the Single-Particle Level

Advances in many different fields rely heavily on the analysis of particles. At the nanoscale, particles attract broad interest and widespread application due to their large surface area and unique properties. At the micro scale, relevant samples include microplastics, atmospheric particulates, nuclear fuel and byproducts, biomedical tags and scaffolds, energy storage materials, just to name a few. Thus, techniques that allow particle characterization are necessary for ensuring engineered properties of interest, environmental monitoring, and understanding their interactions with organisms. Even with the current particle characterization techniques available, it is recognized that non-conventional approaches are necessary to overcome their limitations, including with respect to low sample throughput.
Glow discharge optical emission spectroscopy (GDOES) features many advantages, including fast direct solid sampling, wide dynamic range quantitation, and superb depth profiling resolution down to the nanoscale. In addition, over the last few years, GDOES has shown great potential for surface elemental mapping when the GD is operated in pulsed-power mode and at higher pressures, with the added advantage of obtaining high-pixel density maps with at least three orders of magnitude higher throughput compared to typical techniques. GDOES EM was recently demonstrated to enable fast characterization of nanoparticle suspensions as dried deposits in terms of composition, mass quantitation down to single pg limit of detection, spatial distribution, size, and structural features. Here, recent efforts into advancing GDOES EM toward analysis of nanoparticles will be presented, including improved detection limits beyond pg, microdroplet printed dried deposit arrays, and nanoparticle interactions with cultured cells, as well as harnessing its advantages toward the characterization of microparticles down to the single-particle level.