Systematic Investigations of Plastic Vials Concerning Their Suitability for Ultratrace Anion Analysis in High-Purity Industrial Applications

Abstract.: Ultratrace anion analysis in high-purity industrial applications is done using commercially available plastic vials to store the eluted liquid samples. Plastic vials are manufactured with materials containing several additives. Such additives might potentially release anionic contaminants, thus degrading the blank quality and determination limits (DL). The durability and thermal stability of several materials was found to be a function of anionic species. Fluorinated materials showed the best results for the majority of anions with the exception of fluoride. For the selective analysis of fluoride, polypropylene was found to be the best vial material, together with glass. Cold water extraction showed better results compared to hot water extraction. Over a long observation period, hot water extraction did not at all improve the performance, indicating that this type of supposedly efficient cleaning of the plastic containers to render them less prone to contaminant release does not hold tru

Time resolved sulphur and nutrient distribution in Norway spruce drill cores using ICP-OES

Methods were developed for detailed dendrochemical studies of low sulphur contents in Norway spruce (Picea abies L. Karst.). This tree species is the dominant conifer species in Northern and Central Europe and therefore predestined for a possible use as an environmental archive. Two independent digestion procedures were investigated with respect to their suitability for element determination and optimised for analysis of the low sulphur content in wood. A modified oxygen bomb combustion procedure and a microwave acid digestion procedure were evaluated with the goal to obtain sufficient detection limits in order to access low concentrated non-metals with an appropriate time resolution. Method development included evaluation of strategies preventing losses of volatile sulphur species. Digestion efficiency was demonstrated by recovery rates for various certified plant standard reference materials (NIST 1572, NIST 1547, RM 8436, BCR 101, NIST 1515, RM 8436, NIST 1573, NIST 1575) as well as self prepared standards with defined low sulphur content of 20 to 200mg kg−1, which are typical for Norway spruce wood samples. Ultra sonic nebulisation (USN) was evaluated with respect to signal enhancement for sample introduction to inductively coupled plasma optical emission spectrometry (ICP-OES). The optimised procedure was applied to Norway spruce drill cores from locations with different environmental conditions in Switzerland, in order to investigate the anthropogenic impact of sulphur and the suitability of Norway spruce as an environmental archive for sulphu

Characterizing the Urban Mine—Challenges of Simplified Chemical Analysis of Anthropogenic Mineral Residues

Anthropogenic mineral residues are characterized by their material complexity and heterogeneity, which pose challenges to the chemical analysis of multiple elements. However, creating an urban mine knowledge database requires data using affordable and simple chemical analysis methods, providing accurate and valid results. In this study, we assess the applicability of simplified multi-element chemical analysis methods for two anthropogenic mineral waste matrices: (1) lithium-ion battery ash that was obtained from thermal pre-treatment and (2) rare earth elements (REE)-bearing iron-apatite ore from a Swedish tailing dam. For both samples, simplified methods comprising ‘inhouse’ wet-chemical analysis and energy-dispersive Xray fluorescence (ED-XRF) spectrometry were compared to the results of the developed matrix-specific validated methods. Simplified wet-chemical analyses showed significant differences when compared to the validated method, despite proven internal quality assurance, such as verification of sample homogeneity, precision, and accuracy. Matrix-specific problems, such as incomplete digestion and overlapping spectra due to similar spectral lines (ICP-OES) or element masses (ICP-MS), can result in quadruple overestimations or underestimation by half when compared to the reference value. ED-XRF analysis proved to be applicable as semi-quantitative analysis for elements with mass fractions higher than 1000 ppm and an atomic number between Z 12 and Z 50. For elements with low mass fractions, ED-XRF analysis performed poorly and showed deviations of up to 90 times the validated value. Concerning all the results, we conclude that the characterization of anthropogenic mineral residues is prone to matrix-specific interferences, which have to be addressed with additional quality assurance measures.DFG, 414044773, Open Access Publizieren 2019 - 2020 / Technische Universität BerlinEC/H2020/641999/EU/ Prospecting Secondary raw materials in the Urban mine and Mining waste/ProSU

Stability of aqueous electrolytes based on LiFSI and NaFSI

Through a combination of bulk, interface, and interphase effects, water-in-salt electrolytes, employing a high salt concentration, offer a wider electrochemical stability window than traditional dilute aqueous electrolytes. Here we explore chemical stability, conductivity, viscosity, and electrochemical stability of aqueous solutions of bis(fluorosulfonyl)imide (FSI) salts as electrolytes for lithium-ion and sodium-ion batteries. We demonstrate that the FSI anion is prone to hydrolysis in this environment. However, the kinetics of the reaction strongly depend on salt concentration and nature of the cation. Interestingly, we find that NaFSI solutions are significantly more stable than LiFSI solutions. Highly-concentrated NaFSI solutions also display a wide electrochemical stability window and high conductivity. (C) 2019 Elsevier Ltd. All rights reserved

On Interlayer Stability and High-Cycle Simulator Performance of Diamond-Like Carbon Layers for Articulating Joint Replacements

Diamond like carbon (DLC) coatings have been proven to be an excellent choice for wear reduction in many technical applications. However, for successful adaption to the orthopaedic field, layer performance, stability and adhesion in physiologically relevant setups are crucial and not consistently investigated. In vitro wear testing as well as adequate corrosion tests of interfaces and interlayers are of great importance to verify the long term stability of DLC coated load bearing implants in the human body. DLC coatings were deposited on articulating lumbar spinal disks made of CoCr28Mo6 biomedical implant alloy using a plasma-activated chemical vapor deposition (PACVD) process. As an adhesion promoting interlayer, tantalum films were deposited by magnetron sputtering. Wear tests of coated and uncoated implants were performed in physiological solution up to a maximum of 101 million articulation cycles with an amplitude of ±2° and −3/+6° in successive intervals at a preload of 1200 N. The implants were characterized by gravimetry, inductively coupled plasma optical emission spectrometry (ICP-OES) and cross section scanning electron microscopy (SEM) analysis. It is shown that DLC coated surfaces with uncontaminated tantalum interlayers perform very well and no corrosive or mechanical failure could be observed. This also holds true in tests featuring overload and third-body wear by cortical bone chips present in the bearing pairs. Regarding the interlayer tolerance towards interlayer contamination (oxygen), limits for initiation of potential failure modes were established. It was found that mechanical failure is the most critical aspect and this mode is hypothetically linked to the α-β tantalum phase switch induced by increasing oxygen levels as observed by X-ray diffraction (XRD). It is concluded that DLC coatings are a feasible candidate for near zero wear articulations on implants, potentially even surpassing the performance of ceramic vs. ceramic.ISSN:1422-006

A thermodynamic and experimental study of the conditions of thaumasite formation

The formation of thaumasite was investigated with the progressive equilibrium approach (PEA). This approach experimentally simulates the conditions of various levels of sulfate addition in hardened cement pastes. The influence of limestone, time, C(3)A content, temperature and leaching on thaumasite formation was investigated. The results show that thaumasite formation is favoured at lower temperatures (8 degrees C) independently of the type of cement clinker (high or low C(3)A content) used. Thaumasite was found to form only in systems where limestone was present and where sufficient sulfate had been added. Thaumasite precipitated only in systerns where the Al present has already been consumed to form ettringite and the inolar SO3/Al2O3 ratio exceeded 3. In leached samples (reduction of portlandite and alkalis) slightly less thaumasite was formed whereas gypsum and ettringite are favoured under these conditions. The PEA, used to investigate the chemical aspects of sulfate attack was found to be a good tool for simulating external sulfate attack. Generally, thaumasite was detected were it was modelled to be stable in significant amounts. However, in this study equilibrium conditions were not reached after 9 months. (C) 2007 Elsevier Ltd. All rights reserved

Impact of oxygen content in powders on the morphology of the laser molten tracks in preparation for additive manufacturing of silicon

Powder additive pulsed Nd:YAG laser (wavelength 1064 nm), with the aim of preparing AM of such material. The influence of oxygen content in the initial silicon powders on the continuous tracks morphology was investigated. It was found that the initial oxygen content of the processed powders must be lower than 0.1 wt% to produce a smooth silicon melted track. This result is explained as due to the formation of gaseous manufacturing (AM) of materials is affected by the oxygen present in the raw material, especially if they possess a native oxide. The latter influences the properties of the laser molten track. We carried out a study on the interactions between silicon fine powder (<3 mu m) pellets and a silicon monoxide (SiO) by reaction between silicon and its native oxide during the process. (C) 2019 Elsevier B.V. All rights reserved