Nanoparticle Characterization - Supplementary Comparison on Nanoparticle Size

Abstract

Nanoparticles with size in the range from 10 nm to 300 nm and from three different materials (Au 10 nm, Ag 20 nm, and PSL 30 nm, 100 nm and 300 nm) were used in this supplementary comparison. The selected nanoparticles meet the requirements of different measurement methods such as Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and Differential Mobility Analyzer (DMA), Small Angle X-Ray Scattering and for forth. All 37 participating laboratories returned results, but not all laboratories were able to perform measurement of all 5 nanoparticles. In order to determine the degree of equivalence (DOE), two reference values were considered in this comparison: the method dependent reference value (MRV) and the global reference value (GRV). The MRVs were determined for different measurement methods according to the corresponding reported uncertainties and measurement values from the participants. Each measurement method owns its own MRV. Since the measurement data from DLS were very different from and inconsistent with the measurement data from the other methods, the MRV for DLS was used in the En number calculation for the measurement data reported from the DLS method. The GRV was determined from the MRVs and their uncertainties of all the measurement methods except DLS, and was applied in the En number calculations for the measurement data reported from AFM, EM, DMA and SAXS methods. The assumption that the particles are spherical was commonly made in the nanoparticle measurements. Non-sphericity of particles, if exists, could have different impacts on different measurement methods. It is also important to note that the methods used are measuring mean diameters of a population of particles, not just a single particle, and that the meaning of the mean diameter could differ for different methods. Probably if participants include a different specific contribution in the uncertainty in a harmonized way, taking the non-cancelled method-dependent "systematic" errors into account, it may be easier to compare the results. KEY WORDS FOR SEARCH Nanoparticles; Atomic Force Microscopy (AFM); Transmission Electron Microscopy (TEM); Scanning Electron Microscopy (SEM); Dynamic Light Scattering (DLS); and Differential Mobility Analyzer (DMA); Small Angle X-Ray Scattering Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Particle size distributions for cellulose nanocrystals measured by atomic force microscopy: an interlaboratory comparison

“…It is interesting to note that the difference between probes used by an individual laboratory is in some cases similar to the overdispersion of the consensus mean (Table 1), indicating that this is a significant contributor to the variability between laboratories. The variations between laboratories observed in this study are similar to those observed in two other AFM ILCs of spherical nanoparticles with low polydispersity, although it is not stated whether the data was obtained with one or multiple probes (Meli et al 2012;Lin et al 2019). The present ILC was designed to minimize variability due to CNC dispersion and deposition on mica and it will be of interest to assess the impact this factor in future studies.…”

“…Previously reported AFM studies provide different values for the number of particles required to generate statistically meaningful data sets. Most of these studies imaged spherical nanoparticles with relatively narrow size distributions and, therefore, may not be relevant to polydisperse rod-shaped CNCs (Meli et al 2012;Delvallee et al 2016;Lin et al 2019).…”

“…Notable examples include the characterization of a bimodal silica reference material and 2 ILCs that examined gold, silver, silica and polystyrene nanoparticles (Meli et al 2012;Kestens et al 2016;Lin et al 2019). In 2 of these studies AFM and electron microscopy (EM) were used by multiple labs and the results were compared to those obtained using other particle sizing methods.…”

Um panorama da nanometrologia no Brasil e no mundo

“…Analisando os resultados presentes no Relatório do Programa de Comparação realizado em 2012 (LIN et al, 2019), constata-se que não há homogeneidade entre as leituras realizadas por meio de diferentes métodos (AFM, EM, DMA, SAXS e DLS). Isso resultou na necessidade em separar os diferentes métodos para efetuar a comparação entre os resultados.…”

“…Cabe ressaltar o Programa de Comparação realizado em 2012, que contou com a participação do Inmetro (LIN et al, 2019). Este programa consistiu na medida dimensional de 5 artefatos distintos: ouro (10 nm), prata (20 nm) e poliestireno (30 nm, 100 nm e 300 nm).…”