Single-particle ICP-TOFMS with online microdroplet calibration for the simultaneous quantification of diverse nanoparticles in complex matrices

Abstract

Online microdroplet calibration is used to determine the mass and particle number concentration of inorganic nanoparticles (NPs) without the use of NP standards. This approach can be applied directly to quantify NPs in environmental matrices.

Monodisperse microdroplets: a tool that advances single-particle ICP-MS measurements

“…as natural or engineered. 37,[64][65][66][67][68] In our sp-ICP-TOFMS measurements, we use microdroplet sample introduction in two distinct ways: (1) for online calibration of NP mass in individual NPs, and (2) as a tool to study data analysis approaches for the quantitative detection of fast transient signals, which is critical for reliable PNC determination in sp-ICP-TOFMS. In both of these applications, microdroplets are a exible platform for controlled introduction of discrete masses of analytes which allow us to better probe sp-ICP-TOFMS measurements.…”

“…This setup has been described elsewhere. 33,[35][36][37][38]40,41 In this setup, microdroplets are produced by a microdroplet generator (50 mm diameter Autodrop Pipette, AD-KH-501-L6, MD-E-3000 dispensing system, Microdrop Technologies, GmbH, Germany) and introduced via a falling tube that is lled with a He/ Ar gas mixture to accelerate solvent evaporation so that microdroplets are reduced to dried droplet residues by the end of the falling tube. 26,42 Continuously nebulized samples are introduced via a pneumatic nebulizer and spray chamber, and then mixed with microdroplet-aerosols via a t-piece just in front of the injector base of the ICP torch.…”

“…We have described online microdroplet calibration in several recent publications. [35][36][37] Here, we provide a brief overview of how microdroplet-generated signals provide a route for calibration of element mass in individual analyte nanomaterials. Unlike all other approaches for sp-ICP-MS quantication, online microdroplet calibration does not rely on the use of external reference nanoparticles or the stability of analyte sensitivities and sample transmission efficiencies into the plasma between measurements.…”

“…For both single-nanoparticle and single-cell ICP-MS measurements, introduction of a sample with monodisperse microdroplets presents an attractive approach for quantitative transfer of analyte particles/cells into the plasma with the possibility of direct counting experiments for number concentration determinations. Quantitative transfer of individual microdroplets into the ICP allows for direct determination of absolute detection efficiencies (counts per g) of analyte elements in the microdroplet solution, 26 which can be used to quantify the mass of elements in discrete entities injected into the plasma, such as single nanoparticles, 28,29,[33][34][35][36][37][38] or cells.…”

Versatile Dual-Inlet Sample Introduction System for Multi-Mode Single Particle Inductively Coupled Plasma Mass Spectrometry Analysis and Validation

“…Due to the uniform sample introduction at high transport efficiency of 100% of the µDG, high instrumentspecific analyte sensitivity can be achieved. Depending on the matrix used, this leads to lower limits of detection (LOD) of particle mass and size when compared to the results of conventional introduction systems based on PN 12 . However, due to the design of the µDG, samples cannot be exchanged easily when the ICP-MS system is still operating.…”