When Good Intentions Go Bad-False Positive Microplastic Detection Caused by Disposable Gloves.

Apart from being considered a potential threat to ecosystems and human health, the ubiquity of microplastics presents analytical challenges. There is a high risk of sample contamination during sampling, sample preparation, and analysis. In this study, the potential of sample contamination or misinterpretation due to substances associated with disposable laboratory gloves or reagents used during sample preparation was investigated. Leachates of 10 different types of disposable gloves were analyzed using Raman microspectroscopy (µ-Raman), Fourier-transform infrared microspectroscopy (µ-FTIR), and pyrolysis-gas chromatography/mass spectrometry (pyr-GC/MS). There appeared to be polyethylene (PE) in almost all investigated glove leachates and with all applied methods. Closer investigations revealed that the leachates contained long-chain compounds such as stearates or fatty acids, which were falsely identified as PE by the applied analytical methods. Sodium dodecyl sulfate, which is commonly applied in microplastic research during sample preparation, may also be mistaken for PE. Therefore, µ-Raman, µ-FTIR, and pyr-GC/MS were further tested for their capability to distinguish among PE, sodium dodecyl sulfate, and stearates. It became clear that stearates and sodium dodecyl sulfates can cause substantial overestimation of PE.

Scavenging Reactive Oxygen Species Production Normalizes Ferroportin Expression and Ameliorates Cellular and Systemic Iron Disbalances in Hemolytic Mouse Model.

AIMS: Release of large amounts of free heme into circulation, overproduction of reactive oxygen species (ROS), and activation of toll-like receptor-4-dependent responses are considered critical for the ability of heme to promote oxidative stress and to initiate proinflammatory responses, posing a serious threat to the body. A deep understanding of the consequences of heme overload on the regulation of cellular and systemic iron homeostasis is, however, still lacking. RESULTS: The effects of heme on iron metabolism were studied in primary macrophages and in mouse models of acute and chronic hemolysis. We demonstrated that hemolysis was associated with a significant depletion of intracellular iron levels and increased expression of the sole iron exporter protein, ferroportin. The pathophysiological relevance of this mechanism was further demonstrated in sickle cell anemia mice, which, despite chronic hemolysis, maintained high ferroportin expression and increased iron export. We identified a redox active iron species and superoxide as regulators for ferroportin induction by heme. Scavenging the ROS production, by use of a pharmacological antioxidant N-acetylcysteine, prevented ferroportin induction and normalized intracellular iron levels in macrophages and in experimentally induced hemolysis in mice. INNOVATION: Our data propose that scavenging ROS levels may be a novel therapeutic strategy to balance intracellular iron levels and systemic iron influx in conditions associated with heme overload. CONCLUSION: This study identifies that the pro-oxidant, and not the proinflammatory, actions of heme profoundly impact on iron homeostasis by critically regulating the expression of ferroportin and iron export in hemolytic conditions. Antioxid. Redox Signal. 29, 484-499.

In Situ Crystallization of the Insoluble Anhydrite AII Phase in Graphene Pockets.

Single-distilled water encapsulated in graphene pockets has been studied by aberration-corrected high-resolution transmission electron microscopy and electron energy loss spectroscopy at an acceleration voltage of 80 kV. Inside the graphene pockets, crystallization and in situ crystal growth are reported and identified as the insoluble AII phase of CaSO4 (anhydrite) in a quasi-two-dimensional system. Its formation condition is discussed with respect to the possible temperature and van der Waals pressure between the graphene sheets.

Determination of traffic-related palladium in tunnel dust and roadside soil.

Roadside dust and soil samples were collected at different sites in the area of Ulm and Munich in Germany. Road dust samples were collected in tunnels where the traffic-related dust is less influenced by atmospheric conditions. Soil samples were taken with a drill bar at varying distances to motorways, district and regional roads with different traffic densities. The soil cylinders of 30cm length were divided into four sections in order to obtain depth profiles for palladium (Pd) distribution. Determination of Pd in total digests of the samples was performed by ligand-assisted selective separation and preconcentration of Pd(II) using solid phase extraction followed by high-resolution continuum source graphite furnace spectrometry. The analytical procedure was successfully validated using the certified reference material BCR-723 Road Tunnel Dust and by recovery experiments in spiked soil samples. The average Pd concentration found in the road dusts was 311µgkg-1, the maximum Pd concentration in the topsoil layer was 193µgkg-1. Pd depth profiles reveal transportation of Pd into deeper soil layers, where even at a depth of 25 to 30cm a Pd concentration of 19µgkg-1 was found, proving the high mobility of Pd. Different factors like traffic density and age of the soils are discussed in the context of the found Pd depth profiles.

Multivariate determination of 13CO2/12CO2 ratios in exhaled mouse breath with mid-infrared hollow waveguide gas sensors.

The (12)CO2/(13)CO2 isotope ratio is a well-known marker in breath for a variety of biochemical processes and enables monitoring, e.g., of the glucose metabolism during sepsis. Using animal models-here, at a mouse intensive care unit-the simultaneous determination of (12)CO2 and (13)CO2 within small volumes of mouse breath was enabled by coupling a novel low-volume hollow waveguide gas cell to a compact Fourier transform infrared spectrometer combined with multivariate data evaluation based on partial least squares regression along with optimized data preprocessing routines.

Breath analysis with broadly tunable quantum cascade lasers.

With the availability of broadly tunable external cavity quantum cascade lasers (EC-QCLs), particularly bright mid-infrared (MIR; 3-20 µm) light sources are available offering high spectral brightness along with an analytically relevant spectral tuning range of >2 µm. Accurate isotope ratio determination of (12)CO2 and (13)CO2 in exhaled breath is of critical importance in the field of breath analysis, which may be addressed via measurements in the MIR spectral regime. Here, we combine for the first time an EC-QCL tunable across the (12)CO2/(13)CO2 spectral band with a miniaturized hollow waveguide gas cell for quantitatively determining the (12)CO2/(13)CO2 ratio within the exhaled breath of mice. Due to partially overlapping spectral features, these studies are augmented by appropriate multivariate data evaluation and calibration techniques based on partial least-squares regression along with optimized data preprocessing. Highly accurate determinations of the isotope ratio within breath samples collected from a mouse intensive care unit validated via hyphenated gas chromatography-mass spectrometry confirm the viability of IR-HWG-EC-QCL sensing techniques for isotope-selective exhaled breath analysis.