Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles

We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles

Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles

We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, "Nanoparticle Populations" of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles

Gas-phase studies on the reactivity of charged, aromatic σ,σ,σ-triradicals by using distonic ion approach and Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry

Reactive intermediates with unpaired electrons, such as organic monoradicals and polyradicals, play an important role in organic synthesis, development of new organic materials, and the biological activity of organic compounds. While the chemical properties of various mono- and biradicals have been examined theoretically and experimentally, no reactivity studies have appeared previously on related triradicals. The research on these species was limited to the generation of three such species, and theoretical investigations of their and other triradicals\u27 electronic states and structures. This thesis describes the first reactivity study on a σ,σ,σ–triradicals. The Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR) and “distonic ion approach” were employed to characterize the reactivity of σ,σ,σ–triradicals. The understanding of the reactivity of triradicals cannot be achieved without knowledge of related mono- and biradicals. Therefore, the discussion about the reactivities of the σ,σ,σ–triradicals is preceded by description of chemical behavior of related σ–mono- and σ,σ–biradicals. The examination of the reactivities of a new pyridine-based monoradicals toward selected neutral reagents extends knowledge about chemical behavior of these species. Similarly to previously reported studies, the observed reaction efficiency ordering in most cases correlates well with ordering of the monoradicals electron affinities. The characterization of the chemical properties of the six unsubstituted didehydropyridinium ions and examination of the effect of the substitution on the reactivity of meta-isomers provides valuable data to biradicals reactivity controlling factors studies. The reactivity of the all biradicals is controlled by electron affinity and singlet-triplet gap. The reactivity of the meta-biradicals is additionally controlled by dehydrocarbon atom separation. The first reactivity studies on a σ,σ,σ–triradicals, tridehydropyridinium ions, not only provide information about the chemical properties of the triradicals but also advance our understanding of the spin/spin interactions within the polyradicals. Additionally, the effect of the substitution on the reactivity of one of the isomeric tridehydropyridinium ions is described

Bacillus spp. Cells Captured Selectively by Phages and Identified by Surface Enhanced Raman Spectroscopy Technique

Surface Enhanced Raman Spectroscopy (SERS), has been employed as a rapid and accurate tool for recognition and classification of different microorganisms. The vibrational spectrum intrinsically provides the fingerprint of the molecular structure of microorganisms, without sample preparation. The characterization of Bacillus spp., used as a simulants of the dangerous Bacillus anthracis by means of SERS technique has been carried out. The positive results on the use of the SERS substrate functionalized with phages specific for bacteria are showed. This work is a part of the RAMBO project (Rapid Air particle Monitoring against BiOlogical threats) funded by EDA (European Defense Agency) whose goal is the development of an advanced “detect to warn sensor” of cells and spores of dangerous bacteria, with high performance, good selectivity and reliability

Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles

We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, “Nanoparticle Populations” of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles

Versailles project on advanced materials and standards (VAMAS) interlaboratory study on measuring the number concentration of colloidal gold nanoparticles

We describe the outcome of a large international interlaboratory study of the measurement of particle number concentration of colloidal nanoparticles, project 10 of the technical working area 34, “Nanoparticle Populations” of the Versailles Project on Advanced Materials and Standards (VAMAS). A total of 50 laboratories delivered results for the number concentration of 30 nm gold colloidal nanoparticles measured using particle tracking analysis (PTA), single particle inductively coupled plasma mass spectrometry (spICP-MS), ultraviolet-visible (UV-Vis) light spectroscopy, centrifugal liquid sedimentation (CLS) and small angle X-ray scattering (SAXS). The study provides quantitative data to evaluate the repeatability of these methods and their reproducibility in the measurement of number concentration of model nanoparticle systems following a common measurement protocol. We find that the population-averaging methods of SAXS, CLS and UV-Vis have high measurement repeatability and reproducibility, with between-labs variability of 2.6%, 11% and 1.4% respectively. However, results may be significantly biased for reasons including inaccurate material properties whose values are used to compute the number concentration. Particle-counting method results are less reproducibile than population-averaging methods, with measured between-labs variability of 68% and 46% for PTA and spICP-MS respectively. This study provides the stakeholder community with important comparative data to underpin measurement reproducibility and method validation for number concentration of nanoparticles.peerReviewe