Intra-laboratory assessment of a method for the detection of TiO2 nanoparticles present in sunscreens based on multi-detector asymmetrical flow field-flow fractionation

In this study, an intra-laboratory assessment was carried out to establish the effectiveness of a method for the detection of TiO2 engineered nanoparticles (ENPs) present in sunscreen containing nano-scale TiO2 and a higher nanometer-range (approx. 200-500 nm) Ti02, as well as iron oxide particles. Three replicate measurements were performed on five separate days to generate the measurement uncertainties associated with the quantitative asymmetrical flow field-flow fractionation (AF4) measurement of the hydrodynamic radius r(h, mode1) (MALS), rh,,odei (ICP-MS), r(h, mode2) (ICP-MS), and calculated mass-based particle size distribution (d(10), d(50), d(90)). The validation study demonstrates that the analysis of TiO2 ENPs present in sunscreen by AF4 separation-multi detection produces quantitative data (mass-based particle size distribution) after applying the sample preparation method developed within the NanoDefine project with uncertainties based on the precision (u(IP)) of 3.9-8.8%. This method can, therefore, be considered as the method with a good precision. Finally, the bias data shows that the trueness of the method (u(t) = 5.5-52%) can only be taken as a proxy due to the lack of a sunscreen standard containing certified TiO2 ENPs

Recent developments in mass spectrometry for the characterization of micro- and nanoscale plastic debris in the environment

Development of analytical methods for the characterization (particle size determination, identification, and quantification) of the micro- and nanoscale plastic debris in the environment is a quickly emerging field and has gained considerable attention, not only within the scientific community, but also on the part of policy makers and the general public. In this Trends paper, the importance of developing and further improving analytical methodologies for the detection and characterization of sub-20-mu m-range microplastics and especially nanoplastics is highlighted. A short overview of analytical methodologies showing considerable promise for the detection and characterization of such micro- and nanoscale plastic debris is provided, with emphasis on recent developments in mass spectrometry (MS)-based analytical methods. Novel hyphenated techniques combining the strengths of different analytical methods, such as field flow fractionation and MS-based detection, may be a way to adequately address the smallest fractions in plastic debris analysis, making such approaches worthwhile to be further explored

Detection of microplastics using inductively coupled plasma-mass spectrometry (ICP-MS) operated in single-event mode

The occurrence of microplastics in many, if not all environmental compartments is a matter of increasing concern and deserves proper attention. However, there is still a lack of analytical tools for straightforward monitoring of these tiny plastic particles at environmentally relevant levels in water. Inductively coupled plasma-mass spectrometry (ICP-MS) operated in single-particle mode (SP-ICPMS) was demonstrated to be a powerful technique for the characterization of metallic nanoparticles, but to the best of the authors' knowledge, SP-ICP-MS has not yet been evaluated for the purpose of detection of microplastics and their quantitative determination (particle number density). In this work, spherical polystyrene microspheres of 1 and 2.5 mu m - to mimic microplastics coming from plastic waste - have been detected using ICP-MS. The approach developed relies on the ultra-fast monitoring of transient signals (with a dwell time of 100 mu s) when using a quadrupole-based ICP-MS unit in the so-called single-event mode and registering the signal spikes produced by individual microparticles by monitoring the signal intensity at amass-to-charge ratio (m/z) of 13(C-13(+)). The accuracy of the number-based concentration results (particle number densities) has been assessed by comparing the number of events detected when monitoring C-13(+) to those detected when monitoring Ho-165(+) for 2.5 mm lanthanide-doped polystyrene beads. Additionally, the results obtained for both polystyrene microspheres in terms of size (most frequently occurring intensity of the signal distribution) compare well with the size as determined using electron microscopy. ICP-MS operated in single-event mode thus allows information on both the size distribution and mass concentration of microplastics to be obtained. As this approach makes use of instrumentation already available in many routine labs analyzing environmental samples, it can enable these labs to analyze microplastics by using their instrument in single-event mode

Platinum nanoclusters made by gas-diffusion electrocrystallization (GDEx) as electrocatalysts for methanol oxidation

The development of high-performance electrocatalysts is critical for enhancing the performance and commercial viability of direct methanol fuel cells (DMFCs), which hold the potential to transform the way we power portable electronics and off-grid systems. In this study, we have employed the gas-diffusion electrocrystallization process (GDEx) at room temperature to synthesize platinum nanoclusters (NCs), using different concentrations of polyvinylpyrrolidone (PVP) to stabilize the NPs. The morphology, structure, and composition of the Pt NCs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Single-particle inductively coupled plasma-sector field mass spectrometry (spICP-SFMS) and X-ray diffraction (XRD). Moreover, we assessed the electrocatalytic activity of the Pt NCs for methanol oxidation in both acidic and alkaline media. TEM and SEM analyses revealed Pt NCs of 30 nm-60, composed of much smaller primary nanoparticles with a diameter ranging from 2-4 nm. PVP played a crucial role in preventing diffusion limited aggregation of the Pt NCs. PVP-stabilized GDEx-made Pt NCs demonstrated superior electrocatalytic activity for methanol oxidation compared to aggregated Pt NCs and commercial Pt/C, which can be attributed to the porous structure of the Pt NCs, resulting in a high effective surface area. This study underscores the potential of the GDEx process as a simple and efficient strategy for synthesizing nanomaterials with remarkable catalytic activity and stability for electrochemical energy applications such as direct methanol fuel cells. High-performance electrocatalysts is critical for enhancing the performance and commercial viability of direct methanol fuel cells (DMFCs), which hold the potential to transform the way we power portable electronics and off-grid systems

Mass spectrometry as a powerful analytical tool for the characterization of indoor airborne microplastics and nanoplastics

Development of analytical methods for the characterization (particle size determination, chemical identification, and quantification) of the low mu m-range microplastics (MPs; 1-10 mu m) and nanoplastics (NPs; 1 nm to 1 mu m) in air - coarse (PM10; <10 mu m), fine (PM2.5; <2.5 mu m) and ultrafine (PM1; <1 mu m) particulate matter - is a quickly emerging scientific field as inhalation has been identified as one of the main routes of human exposure. The respiratory tract may serve as both target tissue and port of entry to the systemic circulation for the inhaled MPs and NPs with their small particle size. As an outcome, the interest of the scientific community, policy makers, and the general public in indoor airborne MPs and NPs increased tremendously. However, there is a lack of detailed knowledge on the indoor and outdoor sources of MPs and NPs, their levels, and their health impact. This is mainly related to a lack of standardized sampling and analytical methods for size determination, chemical identification, and quantification. In this review, recent developments in mass spectrometry-based analytical methods for size determination, chemical identification, and quantification of the MPs and NPs in indoor air and dust, are discussed

Characterisation, availability, and risk assessment of the metals in sediment after aging

The behavior of metals in sediments after their disposal to land has important implications for the environmental management. The sediment from the Carska Bara (Serbia) was polluted with adequate metal salts in order to reach severe contamination based on the pseudo-total metal content of Pb, Cd, Ni, Zn, Cu, and Cr according to the corresponding Dutch standards and Canadian guidelines. The toxicity and fate of the metal in sediment depend on its chemical form, and therefore, quantification of the different forms of a metal is more meaningful than the estimation of its total concentration. In this study, fractionation of metals in sediment has been investigated to determine its speciation and ecotoxic potential, as well as evaluation of metal potential toxicity based on the simultaneously extracted metals (SEMs) and acid volatile sulfides (AVSs) analysis at the beginning of the experiment and after 5 weeks of sediment aging. The investigations suggest that Cd, Pb, and Zn have a tendency to associate with labile fraction, the most mobile and most dangerous fraction for the environment. Risk assessment code revealed their high risk. Copper and chromium showed low to medium risk to the aquatic environment. Nickel showed no risk to the aquatic environment. This was the case at the beginning and after 5 weeks of aging. Aging yielded an increased mobility of all metals based on the increased proportion in mobile fractions. The I [SEM pound (i) ]/[AVS] ratio was found to be > 1 both at the beginning and after 5 weeks of aging, with the ratio showing an increase with time. This ratio indicates the potential availability/toxicity and, according to the US EPA criteria, the samples belong to the group with probable negative effect. If particular metals are considered, only the I [SEM pound (i) ]/[AVS] ratio for zinc was > 1 at the beginning. After 5 weeks, the ratio was > 1 for zinc, lead, and copper. Comparison of the results of sequential extraction and the results of SEM and AVS analysis showed good agreement for lead and zinc