Sanitär- und Kommunaltechnik; Umwelttechnik
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Flame retardants are increasingly used in consumer products as e.g. electronics and furniture as well as in construction. Along with the increased usage, concerns about negative effects of flame retardants on human health and the environment have been raised. Concerning construction products one application for flame retardants is the furnishing of steel structures with reactive flameproof coatings. These coatings consist of a complex mixture of different chemicals, additives and solvents. For the evaluation of the risk possibly posed by their application to the environment, this whole mixture should be tested.
Two different leaching tests were applied according to DIN/TS 16637-2 (sample permantly submerged in water) and DIN EN 16105 (immersion and drying cycles), respectively, which can be used for plate-like products. Eluates were divided into subsamples for the measurement of different parameters: pH-value, conductivity, total organic carbon (TOC), cation and anion concentration. For screening of organic compounds, aqueous samples were liquid/liquid extracted using three solvents with different polarity (toluene, hexane and ethylacetate). GC-MS chromatograms were recorded in the SCAN mode and mass spectra of the peaks were compared with spectras stored in the NIST library.
Eluates of leaching test accroding to DIN CEN TS 16637-2 showed low electrical conductivity (20 to 150 µS/cm) and low release of cation and anions often near the LOQ. Diffferences could be observed for plates treated with the reactive coating at both sides and plates coated only at one side, while the other side is only furnished by the corrosive protection layer. Release of TOC and Zn was approx twice or 10 fold higher in the case of plates coated on one side. Furthermore, the comparison of the results for both types of plates showed that a large portion of the released compounds originate rather from the corrosion protection layer than from the reactive coating itself. Leaching tests according to DIN EN 16105 have not been finished yet, but first results show that the conductivity is much lower (1-4 µS/cm) than for the tests according to DIN/TS 16637-2 leading to the assumption that the release of compounds is lower.
By comparison of the mass spectra with library data, mainly organic solvents as xylene, 1-methoxy-2-propanol acetate and n-btuyl carbamate have been tentatively identified so far in the first test fraction done by DIN CEN TS 16637-2.
To understand the metabolic fate of food relevant mycotoxins in vitro systems were mainly used as the method of choice, so far. Yet, in recent years coupling of electrochemistry mass spectrometry (EC-MS) gained increasing importance as promising technique for fast simulation of metabolic processes and was successfully applied in particular for drug metabolism [1].
The aim of our work was to investigate the potential of EC-MS to predict phase I metabolites of priority mycotoxins and to compare the results with in vitro experiments. Hence, the EU-regulated Fusarium mycotoxins zearalenone (ZEN) and patulin as well as dihydroergocristine (DHEC) as model compound of ergot alkaloids were electrochemically oxidized and analyzed by EC MS for the first time.
Electrochemical conditions were set-up individually for each of the three mycotoxins. By using a coulometric flow through cell with a diamond working electrode oxidation of the chosen mycotoxins was observed after applying potentials between 1.7 and 2.0 V vs. Pd/H2. The electrochemically generated reaction products were analyzed online by mass-spectrometric detection.
All of the three chosen mycotoxins were electrochemically converted to mono- and/or dihydroxylated products confirming the results of ZEN related metabolism studies [2, 3] and in case of DHEC own results from in vitro assays. Due to a lack of metabolism studies concerning the oxidative fate of patulin, interpretation of EC-MS data and performing microsomal studies is of particular relevance.
Beside the identified products from electrochemical oxidation of ZEN, patulin and DHEC there is still a number of yet unknown compounds. Additional structural characterization of detected compounds by NMR and X-ray analysis will be facilitated by their large-scale production using preparative EC cells.
The organophosphate nerve agents Tabun (GA), Sarin (GB) and Soman (GD) are among the most toxic chemical warfare agents (CWA) known, and exert their biological effects by irreversibly inhibiting acetylcholinesterase enzymes of the human nerve system. The use of these agents in the past century has killed millions of civilians around the world during World Wars I and II, and after that, approximately 40.000 tons of chemical ammunition were dumped into the Baltic Sea, containing ca. 13.000 tons of chemical warfare agents. Since their production, almost all the nations of the world have been strictly avoiding the development and use of CWA, participating in active destruction of CWA stockpiles, especially since the Chemical Weapon Convention (CWC) of 1993. However, CWA have been used in offensive ways against civilian population by terrorists, as for instance in the fatal Tokyo subway terror incident of 1995 or, most recently, against antigovernment demonstrators in Syria in 2013. Due to their higher toxicity and continuous use, it is therefore very important to develop simple and fast detection methods relying on new nerve agent sensing modalities for use in control and inspection.
A practically useful fluorescent probe must possess a rapid response and high sensitivity, and shall be implementable into easy-to-use devices for real time detection by untrained personnel. Taking into account this fact, in this work we have synthesized several mesoporous silica materials containing boron–dipyrromethene (BODIPY) moieties for the detection of nerve agents GA, GB and GD in the gas phase. Development of our system indicated that the most potent materials are able to respond to the presence of nerve agent simulants diethyl cyanophosphonate, diethyl chlorophosphate and diisopropyl fluorophosphate, which have to be used in a laboratory setting, yet also for the real nerve agents Sarin, Soman and Tabun, producing a strong quenching of the fluorescence. Furthermore, a portable device for the detection of GA, GB and GD in the gas phase has been prepared for in situ sensing and rapid screening applications, consisting of strips that are able to indicate the targets down to below 1 mgm-3 which is below the LD50 values.
Influence of the of dealumination and porosity on the acid sites of natural zeolite clinoptilolite
(2016)
Heavy feedstock from crude and bio oil is a widely available and renewable resource for production of fuel and starting materials for other organic valuables by cracking or hydrocracking. Catalytic processing of heavy feedstock can meet the increased demand of energy up to a great extent. It requires the application of acidic catalysts like zeolites. However, the used synthetic catalysts are difficult to recover and reuse and are mostly spent.
The use of natural zeolite as spent catalysts may open new perspectives in the chemical use of heavy feed feedstock by chemical conversion. Natural zeolites are not expensive, widely available and environment friendly. Clinoptilolite is the most abundant natural zeolite. Clinoptilolite has a crystalline structure with a defined micropore system of medium size showing unique ion exchange and sorption properties. However, it is catalytically active only in the H-form. Also certain porosity is required for improvement of the accessibility of active sites.
This paper deals with the tuning of acid properties and of the mesoporosity of the clinoptilolite by variation of the Si/Al framework ratio, extra-framework aluminum and modification of the porosity by specific acid and water vapor treatment. The preparation of hierarchical pore structures containing interconnected micro-meso-macropores is an important factor influencing the catalytic performance.
The obtained materials have been characterized by XRD, TEM, FTIR, Raman, TG/DSC. The chemical composition has been determined by ICP-AES. The porosity have been investigated by nitrogen adsorption desorption measurements. The acidity has been measured by Ammonia-TPD. The extent of dealumination, stability of the clinoptilolite against acid treatment and the change in the nature of acid sites and their local structure has been studied by solid state 29Si and 27Al MAS NMR spectroscopy in detail. The catalytic activity has been investigated in the acetalization of benzaldehyde with 1,3-butanediol. The impact of the porosity, change of the Si/Al ratio as well as present Al species on catalytic properties will be discussed.
Tapping mode AFM (TM-AFM) is a standard technique to image biomolecules and cells avoiding damage to susceptible samples.
For preparing AFM samples we fixed (untreated and radiated) plasmids chemically on ultra-smooth mica silanized with APTES.
The recorded AFM images were examined concerning the contour length, the conformation and the writhing number of the plasmids.
We found that the measured contour length is in accordance with the number of base pairs. Apart from that, we indicate different structures of plasmids from our AFM images, which were assigned to our plasmid data from agarose gel-electrophoresis.
One-part-geopolymers, produced by addition of water to a mixture of solid silica and sodium alumi-nate, are a less exhaustively studied approach to form geopolymeric binders. Depending on the silica source, the reaction products show significant amounts of zeolite Na-A besides amorphous compounds. Previously, 29Si MAS NMR has been used to analyze the chemical structure of such one-part geopolymers, having crystalline structures and amorphous phases (Q2, Q3, Q4).
In this work, pure zeolites and three different one-part-geopolymers cured for 1 day were investigated by 29Si-27Al TRAPDOR NMR. It was used to identify aluminum phases in overlapping silicon sites. Zeolites Na-X (Si/Al=1.4) and Na-Y (Si/Al=2.7) served as model systems to measure the TRAPDOR effect of the structural units Q4(mAl). Both materials show several Q4(mAl) signals, which are all separated by their chemical shifts. The more aluminum surrounds the silicon tetrahedron the higher are the normalized TRAPDOR difference signals (S0/∆S). The intensity ratios between Q4(mAl) to Q4({m-1}Al) of these signals is fixed but vary slightly between both zeolites. These results are transferred to the complex geopolymer structure.
Many microorganisms possess circular molecules of plasmid DNA. Their conformation may vary from more compact to relaxed forms. Structural changes have important consequences for the physiological role of plasmids and will influence plasmid transcription, replication and their susceptibility to environmental stresses. Radiation is a common form of stress and can cause structural damage to DNA such as single (SSB) and double strand breaks (DSB). Recently, it has been indicated that secondary low-energy electrons play an important role in biological damage under vacuum condition. Therefore, our studies focus on irradiating the plasmid pUC19 with low-energy electrons for the first time under physiological conditions.
N4-acetyl-SMX is the most important cross-reacting compound for the SMX-ELISA with concentrations of 1064 - 2488 ng/L in influent wastewater and 40 - 160 ng/L in effluent wastewater.
The ELISAgrams for estrone show less interfering signals than for SMX.
ELISAgrams of SMX and estrone display in effluent wastewater more interfering signals than in influent wastewater.
Pyrotechnic smoke generators fall under the Directive 2013/29/EU in Europe and could potentially belong to all categories except consumer fireworks. These types are especially present in the field of “Other Pyrotechnic Articles” of the categories P1 and P2, e.g. as simulation devices for paintball or airsoft gaming. The specific users of these products are aware of the corresponding smoke liberation during use and usually wear protective equipment to minimize exposure to potentially harmful aerosols. However, such products are often misused against the labelling requirements in locations where these articles are not supposed to be used, like football stadiums and demonstrations. In contrast to the intended use, uninvolved third parties are likely exposed to these reaction products without proper protective equipment. This study aims at identifying the transient particle size range of the aerosols emitted during the functioning of such common smoke generators for simulation purposes. In total four different types of articles were investigated, with five colors per type (white, blue, green, red, orange). Results show that the majority of the particles were emitted in a range between 40 nm and 350 nm, with some variation depending on the smoke color. Particles with diameters of less than 100 nm are generally of specific concern, as they can penetrate the alveolar system of the human lungs and therefore present a specific hazard.