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Single-particle inductively coupled plasma mass spectrometry (spICP-MS) has been used for particle size measurement of diverse types of individual nanoparticles and micrometer-sized carbon-based particles such as microplastics. However, its applicability to the measurement of micrometer-sized non-carbon-based particles such as silica (SiO2) particles is unclear. In this study, the applicability of spICP-MS to particle size measurement of non-porous/mesoporous SiO2 microspheres with a nominal diameter of 5.0 µm or smaller was investigated. Particle sizes of these microspheres were measured using both spICP-MS based on a conventional calibration approach using an ion standard solution and scanning electron microscopy as a reference technique, and the results were compared. The particle size distributions obtained using both techniques were in agreement within analytical uncertainty. The applicability of this technique to the detection of metal-containing protein-binding mesoporous SiO2 microspheres was also investigated. Bound iron (Fe)-containing proteins (i.e., lactoferrin and transferrin) of mesoporous SiO2 microspheres were detected using Fe as a presence marker for the proteins. Thus, spICP-MS is applicable to the particle size measurement of large-sized and non-porous/mesoporous SiO2 microspheres. It has considerable potential for element-based detection and qualification of bound proteins of mesoporous SiO2 microspheres in a variety of applications. [ABSTRACT FROM AUTHOR]

Single particle inductively coupled plasma mass spectrometry has been used for size measurements of individual nanoparticles (NPs). Here, uncertainties in size analysis based upon two calibration approaches were evaluated: (i) the use of particle size standard and (ii) the use of ion standard solution. For particle size standard approach, the source of uncertainty to determine the target NP diameter was related to the variation in the signal intensities of both target NPs and particle size standard, and the size distribution of the particle size standard. The relative uncertainties of the 50 nm silver NP as the target were 15.0%, 9.9%, and 10.8% when particle size standards of 30 nm, 60 nm, and 100 nm silver NPs were used, respectively. As for the ion standard solution approach, the sources of uncertainty were the concentration of working standard solution, sample flow rate, transport efficiency, slope of calibration curve, and variation in the signal intensity of the ion standard solution and of the target NPs. The relative uncertainties for the 50 nm silver NP were 18.5% for 1 ng/g, 7.6% for 10 ng/g, and 4.7% for 100 ng/g solutions. The lower uncertainty obtained with a high concentration working standard solution is recommended to improve precision on particle size determinations by spICP-MS. [ABSTRACT FROM AUTHOR]

To realize a ∼100% transport efficiency (TE) and a high-throughput sample analysis for nanoparticle characterization using single-particle inductively coupled plasma mass spectrometry (spICP-MS), three sample introduction systems, including a high-performance concentric nebulizer with a heated cyclonic spray chamber and a three-stage Peltier-cooled desolvation system (HPCN-APEX), a conventional sample introduction system (i.e., the commercially available MicroMist nebulizer with a cyclonic spray chamber), and a total consumption (TC) system, were evaluated and compared. The TEs of the HPCN-APEX and TC systems were almost 100% at sample uptake rates of 103 and 9.8 μL min−1, respectively, whereas that of the conventional sample introduction system was only 10% at an uptake rate of 112 μL min−1. Because of the dried aerosol conditions in HPCN-APEX, the size and number detection limits of HPCN-APEX were 1.6-fold and 10-fold lower than those of the TC system. The HPCN-APEX showed better detection efficiency for smaller particles and lower particle numbers. This is beneficial not only for environmental monitoring but also for the ultra-trace analysis of particle impurities in semiconductor process chemicals. [ABSTRACT FROM AUTHOR]

In order to facilitate reliable and efficient determination of both the particle number concentration (PNC) and the size of nanoparticles (NPs) by single-particle ICP-MS (spICP-MS) without the need to correct for the particle transport efficiency (TE, a possible source of bias in the results), a total-consumption sample introduction system consisting of a large-bore, high-performance concentric nebulizer and a small-volume on-axis cylinder chamber was utilized. Such a system potentially permits a particle TE of 100 %, meaning that there is no need to include a particle TE correction when calculating the PNC and the NP size. When the particle TE through the sample introduction system was evaluated by comparing the frequency of sharp transient signals from the NPs in a measured NP standard of precisely known PNC to the particle frequency for a measured NP suspension, the TE for platinum NPs with a nominal diameter of 70 nm was found to be very high (i.e., 93 %), and showed satisfactory repeatability (relative standard deviation of 1.0 % for four consecutive measurements). These results indicated that employing this total consumption system allows the particle TE correction to be ignored when calculating the PNC. When the particle size was determined using a solution-standard-based calibration approach without an NP standard, the particle diameters of platinum and silver NPs with nominal diameters of 30-100 nm were found to agree well with the particle diameters determined by transmission electron microscopy, regardless of whether a correction was performed for the particle TE. Thus, applying the proposed system enables NP size to be accurately evaluated using a solution-standard-based calibration approach without the need to correct for the particle TE. [ABSTRACT FROM AUTHOR]

This study investigates the biosorption mechanism, including cell population behavior, of trace amounts of precious metals (gold, palladium, and platinum) in a unicellular red alga, Galdieria sulphuraria. Single-cell inductively coupled plasma mass spectrometry showed that the number of adsorbing cells and the concentration of adsorbed metal per cell varied depending on solution acidity and metal species. The X-ray absorption fine structure in 5 mM HCl solution indicated that the adsorbed Au formed inner-sphere complexes with S, whereas the adsorbed Pd and Pt formed an inner-sphere complexes with N and/or S. In 500 mM HCl solution, the adsorbed Au and Pd formed inner-sphere complexes only with S, and the Au formed a structure similar to Au 2 S. At higher acidity, Au and Pd were recovered by interacting with residues that formed more stable complexes, which was accompanied by changes in the behavior of cell populations adsorbing the metals. This is the first study to demonstrate the relationship between changes in the behavior of cell populations and chemical interactions that occur between substrate elements and biomaterial residues during biosorption. The findings of this study provide deeper insights into the biosorption mechanism and a background for the design of an environmentally friendly biosorbent. [Display omitted] • Trace precious metal biosorption mechanisms in unicellular red alga were investigated. • Adsorbed Au formed an inner-sphere complex with S in 5 mM HCl. • Adsorbed Pd and Pt formed an inner-sphere complex with N and/or S in 5 mM HCl. • Adsorbed Au and Pd formed an inner-sphere complex with S in 500 mM HCl solution. • Metal–cell interactions altered the behavior of the cells adsorbing precious metals. [ABSTRACT FROM AUTHOR]

To support skill upgrading in analysis of inorganic constituents of environmental and food samples, the National Metrology Institute of Japan (NMIJ) and the National Food Research Institute (NFRI) have organized a proficiency test (PT) of determination of Mn, Fe, Cu, Zn, As, and Cd in brown-rice flour based on the international standard (ISO/IEC 17043:2010). One hundred and thirty-three sets of reports were assessed by use of the E-number and z-score approaches in accordance with ISO/IEC 17043 and the international harmonized protocol for PT. The PT results and analytical procedures, reported in detail, were reviewed, and possible technical reasons for questionable or unsatisfactory results are discussed. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The high electrical conductivity, chemical stability, and low toxicity of elemental Au make it a highly valuable resource. However, wastewater produced during the mining, utilization, and disposal of Au inevitably contains small amounts (10–40 mg L−1) of Au, thus posing environmental risks. It is too acidic to be treated with inexpensive and eco-friendly bioadsorbents previously studied for the remediation of less acidic effluents. Herein, lyophilized Galdieria sulphuraria cells are shown to directly adsorb Au from simulated Au-containing wastewater with a total acid concentration of 4 M, achieving an adsorption capacity of 35 ± 2.5 mg g−1 Au after 30-min exposure and a selectivity that exceeds that of an ion-exchange resin and is comparable to that of activated carbon. Additionally, Au adsorbed on these cells is more easily eluted than that adsorbed on the ion-exchange resin or activated carbon. Detailed characterizations reveal that Au accumulates on the surface of lyophilized cells, where it is mainly present as AuCl 4 − and not as Au0, in contrast to a previously proposed adsorption mechanism. Thus, our work provides valuable insights into the mechanism of Au adsorption on biomaterials and paves the way to the cheap and eco-friendly recovery of Au from acidic wastewater. [Display omitted] • Lyophilized G. sulphuraria cells are used to recover Au from acidic wastewater. • Lyophilization increases the acid tolerance of the cells during Au adsorption. • Lyophilization changed the cellular surface morphology while preserving elemental composition. • The selectivity of cells for Au exceeds that of a representative ion-exchange resin. • Au is adsorbed on the surface of the lyophilized cell mainly as AuCl 4 –. [ABSTRACT FROM AUTHOR]

The demand for precious metals has increased in recent years. However, low concentrations of precious metals dissolved in wastewater are yet to be recovered because of high operation costs and technical problems. The unicellular red alga, Galdieria sulphuraria , efficiently absorbs precious metals through biosorption. In this study, over 90% of gold and palladium could be selectively recovered from aqua regia-based metal wastewater by using G. sulphuraria . These metals were eluted from the cells into ammonium solutions containing 0.2 M ammonium salts without other contaminating metals. The use of G. sulphuraria is an eco-friendly and cost-effective way of recovering low concentrations of gold and palladium discarded in metal wastewater. [ABSTRACT FROM AUTHOR]

Results of proficiency testing (PT) undertaken to assess the analytical skills in Japanese laboratories are presented. The PT was coordinated jointly by the National Metrology Institute of Japan (NMIJ) and the National Food Research Institute (NFRI), in which the determination of As, Cd, Fe, Mn and Zn in a dried powdered squid powder was carried out in compliance with the international standard ISO/IEC 17043:2010. A prescribed protocol for the determination of the moisture content of the sample was given to the participants beforehand. Any sample preparation/extraction methods were not prescribed, and a variety of methods was thus applied by the 118 participants. Reported results were assessed using the E n -number and z -score approaches in accordance with ISO/IEC 17043 and the international harmonized protocol for PT. Results of this PT are reviewed in detail, and technical problems leading to some unsatisfactory results are discussed. [ABSTRACT FROM AUTHOR]

The demand for rare earth elements has increased dramatically in recent years because of their numerous industrial applications, and considerable research efforts have consequently been directed toward recycling these materials. The accumulation of metals in microorganisms is a low-cost and environmentally friendly method for the recovery of metals present in the environment at low levels. Numerous metals, including rare earth elements, can be readily dissolved in aqueous acid, but the efficiency of metal biosorption is usually decreased under the acidic conditions. In this report, we have investigated the use of the sulfothermophilic red alga Galdieria sulphuraria for the recovery of metals, with particular emphasis on the recovery of rare earth metals. Of the five different growth conditions investigated where G. sulphuraria could undergo an adaptation process, Nd(III), Dy(III), and Cu(II) were efficiently recovered from a solution containing a mixture of different metals under semi-anaerobic heterotrophic condition at a pH of 2.5. G. sulphuraria also recovered Nd(III), Dy(III), La(III), and Cu(II) with greater than 90 % efficiency at a concentration of 0.5 ppm. The efficiency remained unchanged at pH values in the range of 1.5-2.5. Furthermore, at pH values in the range of 1.0-1.5, the lanthanoid ions were collected much more efficiently into the cell fractions than Cu(II) and therefore successfully separated from the Cu(II) dissolved in the aqueous acid. Microscope observation of the cells using alizarin red suggested that the metals were accumulating inside of the cells. Experiments using dead cells suggested that this phenomenon was a biological process involving specific activities within the cells. [ABSTRACT FROM AUTHOR]