Flow Injection Single Particle Inductively Coupled Plasma Mass Spectrometry: An Original Simple Approach for the Characterization of Metal-Based Nanoparticles

In recent years, single-particle inductively coupled plasma mass spectrometry (spICPMS) has emerged as a reliable tool that can both count metal-containing nanoparticles and measure their mass, thereby allowing sizing if their shape, density, and composition are known. However, the methodology associated with the current spICPMS approach for mass determination requires determination of both the sample uptake rate and the sample introduction efficiency of the nebulization system. In this paper, the proof of concept of a novel approach based on flow injection (FI) analysis coupled to ICPMS, i.e., FI-spICPMS, is presented. Unlike the established technique, this method does not require a determination of the transport efficiency and of the sample uptake rate for the accurate measurement of particle mass. It also only requires a measurement of the transport efficiency for determination of the particle number. Unlike the traditional spICPMS approach, the measurement of transport efficiency by FI-spICPMS is not affected by changes in sample uptake rate. The efficiency of FI-spICPMS is demonstrated through accurate determination of the particle number and size of 60 nm citrate-coated gold nanoparticles suspended in high-purity water. Despite being simpler, the method provides similar results to those obtained by the established spICPMS method. With a 5 ms dwell time and 200 μs settling time, the size detection limit is 20 nm, i.e., the same as with spICPMS.