Determining Transport Efficiency for the Purpose of Counting and Sizing Nanoparticles via Single Particle Inductively Coupled Plasma Mass Spectrometry

TLDR

Few ideal methods exist for characterizing nanoparticles in complex environmental samples, leaving gaps in toxicity and exposure assessments, while spICPMS can size and count metal‑containing nanoparticles at environmentally relevant concentrations. The paper aims to provide a practical guide for counting and sizing nanoparticles with spICPMS, thereby improving nanometrology for metal‑containing nanoparticles. The authors investigate transport efficiency (nebulization efficiency) measurement methods and offer an alternative protocol for determining particle size applicable to all inorganic nanoparticles. Initial comparison using well‑characterized monodisperse silver nanoparticles showed that accurate transport efficiency is crucial for determining particle number concentration and, with the new protocol, particle size.

Abstract

Currently there are few ideal methods for the characterization of nanoparticles in complex, environmental samples, leading to significant gaps in toxicity and exposure assessments of nanomaterials. Single particle-inductively coupled plasma-mass spectrometry (spICPMS) is an emerging technique that can both size and count metal-containing nanoparticles. A major benefit of the spICPMS method is its ability to characterize nanoparticles at concentrations relevant to the environment. This paper presents a practical guide on how to count and size nanoparticles using spICPMS. Different methods are investigated for measuring transport efficiency (i.e., nebulization efficiency), an important term in the spICPMS calculations. In addition, an alternative protocol is provided for determining particle size that broadens the applicability of the technique to all types of inorganic nanoparticles. Initial comparison, using well-characterized, monodisperse silver nanoparticles, showed the importance of having an accurate transport efficiency value when determining particle number concentration and, if using the newly presented protocol, particle size. Ultimately, the goal of this paper is to provide improvements to nanometrology by further developing this technique for the characterization of metal-containing nanoparticles.