Processing Gray Selenium in Phosphonium-Based Ionic Liquids.

The dissolution of gray selenium in tetraalkylphosphonium acetate ionic liquids was investigated by UV-vis, NMR, and Raman spectroscopy as well as quantum chemical calculations and electrochemical methods. Acetate anions and tetraalkylphosphonium cations facilitate the formation and stabilization of oligoselenides Sen2- and cationic Se species in the ionic liquid phase. Chemical exchange of selenium atoms was demonstrated by variable-temperature 77Se NMR experiments. Additionally, uncharged cycloselenium molecules exist at high selenium concentrations. Upon dilution with ethanol, amorphous red selenium precipitates from the solution. Moreover, crystalline Se1-xTex solid solutions precipitate when elemental tellurium is added to the mixture as confirmed by powder X-ray diffraction and Raman spectroscopy.

Ionometallurgical Step-Electrodeposition of Zinc and Lead and its Application in a Cycling-Stable High-Voltage Zinc-Graphite Battery.

Ionometallurgy is a new development aiming at the sustainable low-temperature conversion of naturally occurring metal ores and minerals to their metals or valuable chemicals in ionic liquids (ILs) or deep eutectic solvents. The IL betainium bis((trifluoromethyl)sulfonyl)imide, [Hbet][NTf2 ], is especially suited for this process due to its redox-stability and specific-functionalization. The potentiostatic electrodeposition of zinc and lead starting directly from ZnO and PbO, which dissolve in [Hbet][NTf2 ] in high concentrations is reported. The initial reduction potentials of zinc(II) and lead(II) are about -1.5 and -1.0 V, respectively. The ionic conductivity of the solution of ZnO in [Hbet][NTf2 ] is measured and the effect of various temperatures and potentials on the morphology of the deposited material is explored. The IL proves to be stable under the chosen conditions. From IL-solutions, where ZnO, PbO, and MgO have been dissolved, metallic Zn and Pb are deposited under potentiostatic control either consecutively by step-electrodeposition or together in a co-electrodeposition. Using the method, Zn is also deposited on 3D copper foam and assembles into high-voltage zinc-graphite battery. It exhibits a working-voltage up to 2.7 V, an output midpoint discharge-voltage of up to 2.16 V, up to 98.6% capacity-retention after 150 cycles, and good rate performance.

Synthesis and Dissolution of Metal Oxides in Ionic liquids and Deep Eutectic Solvents.

Ionic liquids (ILs) and deep eutectic solvents (DESs) have proven to be suitable solvents and reactants for low-temperature reactions. To date, several attempts were made to apply this promising class of materials to metal oxide chemistry, which, conventionally, is performed at high temperatures. This review gives an overview about the scientific approaches of the synthesis as well as the dissolution of metal oxides in ILs and DESs. A wide range of metal oxides along with numerous ILs and DESs are covered by this research. With ILs and DESs being involved, many metal oxide phases as well as different particle morphologies were obtained by means of relatively simple reactions paths. By the development of acidic task-specific ILs and DESs, even difficultly soluble metal oxides were dissolved and, hence, made accessible for downstream chemistry. Especially the role of ILs in these reactions is in the focus of discussion.

A multicentric randomized study comparing two techniques of magnification assisted loop excision of high-grade cervical intraepithelial neoplasia: video exoscopy and colposcopy.

PURPOSE: To compare loop excisions of cervical intraepithelial neoplasia grade 2 or worse (CIN 2+) under video exoscopy, or colposcopic guidance, with respect to safety and effectiveness. METHODS: Prospective multicentric randomized trial of 300 patients, undergoing loop excision for CIN 2+ either under video exoscopy (group A) or colposcope (group B) guidance. Intra- and post-operative complications, resection margins, and removed cervical volume in both groups were evaluated. RESULTS: 19.3 % of patients in video exoscopy group and 15.5 % in colposcopy group (p = 0.67) had transformation zone (TZ) 3. 45/151 (29.8 %) of group A patients and 48/149 (32.2 %) of group B patients underwent top-hat procedure, i.e., one superficial excision followed by one deeper removal of the endocervical tissue (p = 0.74). There was no difference in intra- and post-operative complications in the two groups. Positive endocervical resection margins (R0) were 9.9 % in video exoscopy group and 8.7 % in colposcopy group, respectively. Unclear endocervical resection margins (Rx) were 2.0 % in both groups. Mean total excised cervical volume was 1.20 cubic centimeter (cc³) in group A, and 1.24 cc³ in group B, respectively. Recurrent disease occurred in 2.3 % of patients at 6 months follow-up. CONCLUSION: Magnification assisted loop excision of CIN 2+ is equally effective and safe under colposcopic and video exoscopy guidance. The latter technique could potentially offer an alternative treatment of CIN 2+ lesions for doctors unfamiliar with colposcope.

Cobalt Deposition from Ionothermally Dissolved Cobalt Oxides.

Owing to the environmental problems of numerous metal production processes, there is a growing need for more energy-efficient approaches. Cobalt is considered a strategic element that is extracted not only from ores but also from spent Li-ion batteries. One promising new approach is ionometallurgy, which is the extraction of metal oxides by ionic liquids (ILs). This study concerns new investigations into ionometallurgical processing of CoO, Co3 O4 , and LiCoO2 in the IL betainium bis(trifluoromethylsulfonyl)imide, [Hbet][NTf2 ]. Three crystal structures of cobalt-betaine complex compounds and combined spectroscopic and diffraction studies provide insights into the dissolution process. In addition, an optimized dissolution procedure for metal oxides is presented, avoiding the previously reported decomposition of the IL. Subsequent cobalt electrodeposition is only possible from cationic complex species, highlighting the importance of a thorough understanding of the complex equilibria. The presented method is also compared to other recently reported approaches.

Critical Investigation of Betaine Hydrochloride-Based Deep Eutectic Solvent for Ionometallurgical Metal Production.

The applicability of a deep eutectic solvent (DES) consisting of betainium hydrochloride, urea and glycerol is examined with respect to ionometallurgical metal extraction and compared with the ionic liquid (IL) betainium bis(trifluoromethylsulfonyl)imide ([Hbet][NTf2 ]). The DES dissolves numerous metal oxides, where not only betaine and chloride act as stabilizing ligands, but also nascent ammonia seems to be essential. From such solutions, cobalt, copper, zinc, tin, lead, and even vanadium can be electrodeposited, demonstrating the feasibility of ionometallurgy. However, repeated recycling of the DES is not conceivable. NMR spectroscopy and mass spectrometry identify numerous decomposition reactions taking place at 60 °C already. The by-products that are formed not only make recycling more difficult, but also pose a toxicity problem. The opportunities and obstacles of DESs and ILs for their application in ionometallurgy are critically discussed. It is shown that a thorough understanding of the underlying chemical processes is critical.

Rising and Falling High-Sensitivity Cardiac Troponin in Diagnostic Algorithms for Patients With Suspected Myocardial Infarction.

Background High-sensitivity cardiac troponin (hs-cTn)-based diagnostic algorithms are recommended for the management of patients with suspected myocardial infarction (MI) without ST elevation. Although mirroring different phases of myocardial injury, falling and rising troponin patterns (FPs and RPs, respectively) are equally considered by most algorithms. We aimed to compare the performance of diagnostic protocols for RPs and FPs, separately. Methods and Results We pooled 2 prospective cohorts of patients with suspected MI and stratified patients to stable, FP, and RP during serial sampling separately for hs-cTnI and hs-cTnT and applied the European Society of Cardiology 0/1- and 0/3-hour algorithms comparing the positive predictive values to rule in MI. Overall, 3523 patients were included in the hs-cTnI study population. The positive predictive value for patients with an FP was significantly reduced compared with patients with an RP (0/1-hour: FP, 53.3% [95% CI, 45.0-61.4] versus RP, 76.9 [95% CI, 71.6-81.7]; 0/3-hour: FP, 56.9% [95% CI, 42.2-70.7] versus RP, 78.1% [95% CI, 74.0-81.8]). The proportion of patients in the observe zone was larger in the FP using 0/1-hour (31.3% versus 55.8%) and 0/3-hour (14.6% versus 38.6%) algorithms. Alternative cutoffs did not improve algorithm performances. Compared with stable hs-cTn, the risk for death or MI was highest in those with an FP (adjusted hazard ratio [HR], hs-cTnI 2.3 [95% CI, 1.7-3.2]; RP adjusted HR, hs-cTnI 1.8 [95% CI, 1.4-2.4]). Findings were similar for hs-cTnT tested in 3647 patients overall. Conclusions The positive predictive value to rule in MI by the European Society of Cardiology 0/1- and 0/3-hour algorithms is significantly lower in patients with FP than RP. These are at highest risk for incident death or MI. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT02355457, NCT03227159.

Speciation of Copper(II)-Betaine Complexes as Starting Point for Electrochemical Copper Deposition from Ionic Liquids.

The application of ionic liquids for the dissolution of metal oxides is a promising field for the development of more energy- and resource-efficient metallurgical processes. Using such solutions for the production of valuable chemicals or electrochemical metal deposition requires a detailed understanding of the chemical system and the factors influencing it. In the present work, several compounds are reported that crystallize after the dissolution of copper(II) oxide in the ionic liquid [Hbet][NTf2 ]. Dependent on the initial amount of chloride, the reaction temperature and the purity of the reagent, copper crystallizes in complexes with varying coordination geometries and ligands. Subsequently, the influence of these different complex species on electrochemical properties is shown. For the first time, copper is deposited from the ionic liquid [Hbet][NTf2 ], giving promising opportunities for more resource-efficient copper plating. The copper coatings were analyzed by SEM and EDX measurements. Furthermore, a mechanism for the decomposition of [Hbet][NTf2 ] in the presence of chloride is suggested and supported by experimental evidence.

Dissolution of metal oxides in task-specific ionic liquid.

Due to their typically low reactivity, the activation of metal oxides, as found in ores, earths and minerals, is in general performed by high temperature reactions, which consume much energy. Owing to the prevalence of fossil fuels, this is accompagnied by the generation of large amounts of CO2. Alternatively, ionic liquids (ILs) can be used as solvents for metal oxide dissolution and downstream chemistry at much lower temperatures. The dissolution ability of the dry ionic liquid betainium bis(trifluoromethylsulfonyl)imide, [Hbet][NTf2], was investigated for 30 metal oxides at 175 °C and compared to chloride containing IL [Hbet]2[NTf2]Cl. A general dissolution-promoting effect of chloride anions was found, regarding reaction time as well as the variety of dissolved metal oxides. Up to now, the dissolution in [Hbet]2[NTf2]Cl is limited to basic or amphoteric metal oxides and assumed to be influenced by multiple factors, such as reaction conditions and the lattice energy of the metal oxide as well as its crystal structure. Comprehensive investigations were performed for the dissolution of CuO, which led to the discovery of the water-free complex compound [Cu2(bet)4(NTf2)2][NTf2]2. Proceeding from this compound, a complete exchange of the O-coordination sphere by other ligands was demonstrated, opening up promising possibilities for downstream chemistry.

Determination of tributyltin in whole water matrices under the European Water Framework Directive.

Monitoring of water quality is important to control water pollution. Contamination of the aquatic system has a large effect on human health and the environment. Under the European Water Framework Directive (WFD) 2000/60/EC and the related directive on environmental quality standards (EQS) in the field of water policy 2008/105/EC, the need for sensitive reference methods was highlighted. Since tributyltin (TBT) is one of the WFD listed priority substances a method was developed which is capable to qualify and quantify the pollutant at the required low WFD EQS of 0.2ngL(-1) in whole water bodies, i.e. in non-filtered water samples with dissolved organic carbon and suspended particulate matter. Therefore special attention was paid on the interaction of TBT with the suspended particulate matter and humic substances to obtain a complete representation of the pollution in surface waters. Different water samples were investigated varying the content of organic dissolved and suspended matter. Quantification was performed using species-specific isotope dilution (SSID) and gas chromatography with inductively coupled plasma mass spectrometry (GC-ICP-MS). Different sample treatment strategies were evaluated and compared. The process of internal standard addition was investigated and optimized, hence the equilibrium between internal standards and matrix is of primary importance to perform accurate SSID. Samples spiked at EQS level were analyzed with a recovery between 95 and 105 %. Additionally real surface water samples were investigated and the TBT concentration for the whole water body was determined and compared with conventional routine analysis method.

Towards tributyltin quantification in natural water at the Environmental Quality Standard level required by the Water Framework Directive.

The European Union (EU) has included tributyltin (TBT) and its compounds in the list of priority water pollutants. Quality standards demanded by the EU Water Framework Directive (WFD) require determination of TBT at so low concentration level that chemical analysis is still difficult and further research is needed to improve the sensitivity, the accuracy and the precision of existing methodologies. Within the frame of a joint research project "Traceable measurements for monitoring critical pollutants under the European Water Framework Directive" in the European Metrology Research Programme (EMRP), four metrological and designated institutes have developed a primary method to quantify TBT in natural water using liquid-liquid extraction (LLE) and species-specific isotope dilution mass spectrometry (SSIDMS). The procedure has been validated at the Environmental Quality Standard (EQS) level (0.2ngL(-1) as cation) and at the WFD-required limit of quantification (LOQ) (0.06ngL(-1) as cation). The LOQ of the methodology was 0.06ngL(-1) and the average measurement uncertainty at the LOQ was 36%, which agreed with WFD requirements. The analytical difficulties of the method, namely the presence of TBT in blanks and the sources of measurement uncertainties, as well as the interlaboratory comparison results are discussed in detail.

Tributyltin--critical pollutant in whole water samples--development of traceable measurement methods for monitoring under the European Water Framework Directive (WFD) 2000/60/EC.

Tributyltin is listed as one of the priority substances in the European Water Framework Directive (WFD). Despite its decreasing input in the environment, it is still present and has to be monitored. In the European Metrology Research Programme project ENV08, a sensitive and reliable analytical method according to the WFD was developed to quantify this environmental pollutant at a very low limit of quantification. With the development of such a primary reference method for tributyltin, the project helped to improve the quality and comparability of monitoring data. An overview of project aims and potential analytical tools is given.

Experimental design for TBT quantification by isotope dilution SPE-GC-ICP-MS under the European water framework directive.

In Europe the maximum allowable concentration for tributyltin (TBT) compounds in surface water has been regulated by the water framework directive (WFD) and daughter directive that impose a limit of 0.2 ng L(-1) in whole water (as tributyltin cation). Despite the large number of different methodologies for the quantification of organotin species developed in the last two decades, standardised analytical methods at required concentration level do not exist. TBT quantification at picogram level requires efficient and accurate sample preparation and preconcentration, and maximum care to avoid blank contamination. To meet the WFD requirement, a method for the quantification of TBT in mineral water at environmental quality standard (EQS) level, based on solid phase extraction (SPE), was developed and optimised. The quantification was done using species-specific isotope dilution (SSID) followed by gas chromatography (GC) coupled to inductively coupled plasma mass spectrometry (ICP-MS). The analytical process was optimised using a design of experiment (DOE) based on a factorial fractionary plan. The DOE allowed to evaluate 3 qualitative factors (type of stationary phase and eluent, phase mass and eluent volume, pH and analyte ethylation procedure) for a total of 13 levels studied, and a sample volume in the range of 250-1000 mL. Four different models fitting the results were defined and evaluated with statistic tools: one of them was selected and optimised to find the best procedural conditions. C18 phase was found to be the best stationary phase for SPE experiments. The 4 solvents tested with C18, the pH and ethylation conditions, the mass of the phases, the volume of the eluents and the sample volume can all be optimal, but depending on their respective combination. For that reason, the equation of the model conceived in this work is a useful decisional tool for the planning of experiments, because it can be applied to predict the TBT mass fraction recovery when the experimental conditions are drawn. This work shows that SPE is a convenient technique for TBT pre-concentration at pico-trace levels and a robust approach: in fact (i) number of different experimental conditions led to satisfactory results and (ii) the participation of two institutes to the experimental work did not impact the developed model.

Analysis of arsenic species in fish after derivatization by GC-MS.

The derivatization of organoarsenic compounds by different reagents like thioglycolates or dithiols and the subsequent analysis by GC-MS as a molecular specific technique was investigated and described. The possible derivatization reagents methyl- and ethylthioglycolate (TGM and TGE), 1,3-propane- and 1,5-pentanedithiol (PDT and PeDT), which transfer the polar and nonvolatile analytes dimethylarsenate (DMA), monomethylarsonate (MMA), arsenite and arsenate into volatile compounds, were evaluated. The application for real samples like fish material was also studied. In addition the gas chromatographic separation and resolution was optimized and experiments were carried out to determine the highest derivatization rates. Derivatization reagents were evaluated in terms of quantity and stability of the formed chemical species. All derivatization products were characterized by mass spectrometry in order to identify the separated arsenic species. The most efficient conversion of DMA and MMA was observed by using ethylthioglycolate as derivatization agent. Finally, the derivatization procedure and the GC-MS-method were validated to determine linearity, precision, selectivity, analytical limiting values and recoveries. For the proposed method a limit of detection (LOD) of 5.8 pg for DMA and 14.0 pg for MMA was found. The accuracy was established by comparing the mean value measured for DMA in the certified reference material BCR-627 (tuna fish) with the certified one. MMA was not quantified in marine samples due to its low content. In shrimp samples DMA was not detectable. For codfish a DMA-content of 0.20±0.004 mg kg(-1), for "Surströmming" an amount of 0.38±0.02 mg kg(-1) and for herring, which showed the highest amount of DMA, a content of 1.15±0.03 mg kg(-1) was determined.