Kolloide: Die Welt der vernachlässigten Dimensionen

Aquatic colloids are abundant in all natural aquatic systems. Aquatic colloids consist of clay minerals, micro‐organisms, humic substances, and anthropogenic colloids like soot and platinum (from catalysts in motor vehicles). Colloids may enhance contaminant transport due to sorption of hydrophobic organic compounds. They can have negative effects on water quality, especially micro‐organisms like pathogens or viruses. Colloids also can cause pore blocking and subsequent head loss in groundwater production wells. However, colloids can be useful in groundwater remediation or waster water treatment (e.g. tensides, flocculation, catalysts). The origin of colloids is due to weathering, degradation of organic compounds, dissolution or precipitation as well as hydrochemical or hydraulic gradients. Colloid stability is dominated by surface properties. New analytical tools like field flow fractionation, laser induced breakdown detection and scanning x‐ray microscopy will provide new insight into the behaviour of aquatic colloids.     

Aquatic Ecotoxicity Testing of Nanoparticles—The Quest To Disclose Nanoparticle Effects

The number of products on the market containing engineered nanoparticles (ENPs) has increased significantly, and concerns have been raised regarding their ecotoxicological effects. Environmental safety assessments as well as relevant and reliable ecotoxicological data are required for the safe and sustainable use of ENPs. Although the number of publications on the ecotoxicological effects and uptake of ENPs is rapidly expanding, the applicability of the reported data for hazard assessment is questionable. A major knowledge gap is whether nanoparticle effects occur when test organisms are exposed to ENPs in aquatic test systems. Filling this gap is not straightforward, because of the broad range of ENPs and the different behavior of ENPs compared to “ordinary” (dissolved) chemicals in the ecotoxicity test systems. The risk of generating false negatives, and false positives, in the currently used tests is high, and in most cases difficult to assess. This Review outlines some of the pitfalls in the aquatic toxicity testing of ENPs which may lead to misinterpretation of test results. Response types are also proposed to reveal potential nanoparticle effects in the aquatic test organisms.     

Präkolumbianische Chemie

The contribution of non‐European cultures to science and technology, primarily to chemistry, has gained very little attentions until now. Especially the high technological intelligence and inventiveness of South American native populations shall be put into a different light by our contribution. The purpose of this essay is to show that mainly in the area of chemical practices the indigenous competence was considerable and has led to inventions profitable nowadays to millions of people in the western world and especially to the pharmacy corporations. We would like to illustrate this assumption by giving some examples of chemical practices of transformation of substances, mainly those unknown in the Old World. The indigenous capacity to gain and to transform substances shall be shown here by the manufacture of poisons, such as curare or the extraction of toxic substances of plants, like during the fabrication of manioc flower. We shall mention as well other processes of multi‐stage transformations and the discovery and the use of highly effective natural substances by Amazonian native populations, such as, for example, rubber or psychoactive drugs.     

Photoreduction of Terrigenous Fe‐Humic Substances Leads to Bioavailable Iron in Oceans

Humic substances (HS) are important iron chelators responsible for the transport of iron from freshwater systems to the open sea, where iron is essential for marine organisms. Evidence suggests that iron complexed to HS comprises the bulk of the iron ligand pool in near‐coastal waters and shelf seas. River‐derived HS have been investigated to study their transport to, and dwell in oceanic waters. A library of iron model compounds and river‐derived Fe‐HS samples were probed in a combined X‐ray absorption spectroscopy (XAS) and valence‐to‐core X‐ray emission spectroscopy (VtC‐XES) study at the Fe K‐edge. The analyses performed revealed that iron complexation in HS samples is only dependent on oxygen‐containing HS functional groups, such as carboxyl and phenol. The photoreduction mechanism of Fe^III‐HS in oceanic conditions into bioavailable aquatic Fe^II forms, highlights the importance of river‐derived HS as an iron source for marine organisms. Consequently, such mechanisms are a vital component of the upper‐ocean iron biogeochemistry cycle.     

Parallel implementation of efficient charge–charge interaction evaluation scheme in periodic divide‐and‐conquer density‐functional tight‐binding calculations

A low‐computational‐cost algorithm and its parallel implementation for periodic divide‐and‐conquer density‐functional tight‐binding (DC‐DFTB) calculations are presented. The developed algorithm enables rapid computation of the interaction between atomic partial charges, which is the bottleneck for applications to large systems, by means of multipole‐ and interpolation‐based approaches for long‐ and short‐range contributions. The numerical errors of energy and forces with respect to the conventional Ewald‐based technique can be under the control of the multipole expansion order, level of unit cell replication, and interpolation grid size. The parallel performance of four different evaluation schemes combining previous approaches and the proposed one are assessed using test calculations of a cubic water box on the K computer. The largest benchmark system consisted of 3,295,500 atoms. DC‐DFTB energy and forces for this system were obtained in only a few minutes when the proposed algorithm was activated and parallelized over 16,000 nodes in the K computer. The high performance using a single node workstation was also confirmed. In addition to liquid water systems, the feasibility of the present method was examined by testing solid systems such as diamond form of carbon, face‐centered cubic form of copper, and rock salt form of sodium chloride. © 2017 Wiley Periodicals, Inc.     

Investigations for the detection of genotoxic substances on TLC plates

The present study describes modifications to an existing bioautographic method for detecting genotoxic substances on thin-layer chromatography (TLC) plates by using the umu assay. It will be shown that the complex procedure that is described in the literature can be significantly simplified. Using the modified method, it is possible to detect 0.3?ng of the genotoxic substance 4-nitroquinoline-N-oxide. With 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-gal), a suitable substrate for environmental samples for the detection of the resulting β-galactosidase was found. Experiments showed, in contrast, that indirectly genotoxic substances could not thus far be identified on the TLC plate with overlayer bioautography.     

Recent advances in analysis of hazardous genotoxic impurities in pharmaceuticals by HPLC,GC, and CE

Nowadays, genotoxic impurities in pharmaceuticals at lower levels are of increasing concerns not only to pharmaceutical industries but also for the regulatory agencies due to their risks for human carcinogenesis and, thus, requiring manufacturers to pay extra attention for their analysis and control. The need to determine these impurities at trace levels, based on the threshold of toxicological and daily dose, taking into consideration the often reactive and labile nature of genotoxic impurities, which poses significant analytical challenges. Therefore, sensitive and sophisticated analytical methodologies are deemed necessary in order to be able to test and control genotoxic impurities in drug substances. This review demonstrates the approaches reported in the literature for the analysis of the hazardous genotoxic impurities and the strategies used to enhance the sensitivity such as using ion spray-mass spectrometry and the separation techniques for the analysis of such impurities.     

A strategy to study genotoxicity: application to aquatic toxins, limits and solutions

Humans can be exposed to aquatic toxins mainly through contamination of food and water (drinking and recreational). Among these toxins, contamination by both phycotoxins occurring in shellfish and cyanotoxins mostly involved in freshwater bodies are of concern for public health. Whereas regulations exist to evaluate the genotoxicity of most compounds to which humans are exposed, including drugs and chemicals, no regulations have been established for these compounds. In this paper, we show that the same strategy including both in vitro and in vivo tests can be followed to evaluate the genotoxicity of aquatic toxins (phycotoxins and cyanotoxins). However, this strategy encountered different limits which arise when completing an overview of the genotoxic potential of toxins. The most restrictive one is undoubtedly the low amount (even the lack sometimes) of purified toxins available. Solutions and recommendations for testing the genotoxicity of aquatic toxins are suggested to overcome the specific problems encountered with these compounds. It must be kept in mind that recent developments in drug toxicology should be considered and that experiments must be conducted in respect of the 3Rs principle of refinement, reduction and replacement for animal experimentation.     

水产品中有害物质分析样品前处理技术研究进展

水产品含有丰富的蛋白、维生素和多种微量元素,是人们摄取动物性蛋白质的重要来源之一,我国是世界上最大的水产品消费国,其质量安全问题一直备受关注。但水产样品基质复杂,有害物质的含量低,须对其进行分离富集后才能进行检测,传统的液-液萃取、固相萃取和快速固相分散萃取等样品前处理技术在水产品分析中得到广泛应用,同时针对一些挥发性和超痕量有害物质检测时,固相微萃取同样体现出巨大优势。这些样品前处理技术可以有效去除基体对分析对象的干扰,提高检测方法的灵敏度和准确度。根据目标分析物性质的不同,选择合适的样品前处理技术,是水产品中有害物质分析的关键步骤。该文以水产品中有害物的来源不同,将其分为3类:(1)水产品中环境污染物的分析;(2)养殖运输和加工过程中有害物的分析;(3)水产品中生物毒素的分析。以这3类有害物质的分析为主线,综述了近10年水产品中有害物质分析的样品前处理技术,包括液-液萃取、固相萃取、固相微萃取、快速固相分散萃取和磁性固相萃取等。此外,还对各种技术的优缺点进行了探讨,并对其未来发展方向进行了展望。     

Borohydride Ionic Liquids and Borane/Ionic‐Liquid Solutions as Hypergolic Fuels with Superior Low Ignition‐Delay Times

In propellant systems, fuels of choice continue to be hydrazine and its derivatives, even though they comprise a class of acutely carcinogenic and toxic substances which exhibit rather high vapor pressures and require expensive handling procedures and costly safety precautions. Hypergolic ionic liquids tend to have low volatility and high thermal and chemical stability, and often exhibit wide liquid ranges, which could allow the use of these substances as bipropellant fuels under a variety of conditions. A new family of borohydride ionic liquids and borane–ionic‐liquid solutions is described which meets nearly all of the desired important criteria for well‐performing fuels. They exhibit ignition‐delay times that are superior to that of any known hypergolic ionic liquid and may thus be legitimate replacements for hydrazine and its derivatives.     

Analysis of 30 synthetic cannabinoids in serum by liquid chromatography‐electrospray ionization tandem mass spectrometry after liquid‐liquid extraction

The analysis of synthetic cannabinoids in human matrices is of particular importance in the fields of forensic and clinical toxicology since cannabis users partly shift to the consumption of ‘herbal mixtures’ as a legal alternative to cannabis products in order to circumvent drug testing. However, comprehensive methods covering the majority of synthetic cannabinoids already identified on the drug market are still lacking. In this article, we present a fully validated method for the analysis of 30 synthetic cannabinoids in human serum utilizing liquid‐liquid extraction and liquid chromatography‐electrospray ionization tandem mass spectrometry. The method proved to be suitable for the quantification of 27 substances. The limits of detection ranged from 0.01 to 2.0 ng/mL, whereas the lower limits of quantification were in the range from 0.1 to 2.0 ng/mL. The presented method was successfully applied to 833 authentic serum samples during routine analysis between August 2011 and January 2012. A total of 227 (27%) samples was tested positive for at least one of the following synthetic cannabinoids: JWH‐018, JWH‐019, JWH‐073, JWH‐081, JWH‐122, JWH‐200, JWH‐203, JWH‐210, JWH‐307, AM‐2201 and RCS‐4. The most prevalent compounds in positive samples were JWH‐210 (80%), JWH‐122 (63%) as well as AM‐2201 (29%). Median serum concentrations were all below 1.0 ng/mL. These findings demonstrate a significant shift of the market of synthetic cannabinoids towards substances featuring a higher CB₁ binding affinity and clearly emphasize that the analysis of synthetic cannabinoids in serum or blood samples requires highly sensitive analytical methods covering a wide spectrum of substances. Copyright © 2012 John Wiley & Sons, Ltd.     

The association between selenium and humic substances in forested ecosystems—laboratory evidence

In the soils and aquatic systems of coniferous forests, selenium is usually associated with humic substances. To clarify further some of the mechanisms involved, labelled and unlabelled selenite were added to two forest floors and to a brownwater lake. Sequential extraction procedures and chromatographic methods were used to evaluate the resulting association between selenium and humic substances. It was observed that the forest floors fixed most of the added selenite by means of microbial reductive incorporation and that selenium was preferentially incorporated into lowmolecular-weight fractions of the humic substances. By contrast, selenium reduction was much slower in the brown-water lake and instead, inorganic complexation of selenite to metal–humic complexes was important during the experiment, provided that the concentrations of competing ligands were low.     

Interfacing the GROMOS (bio)molecular simulation software to quantum‐chemical program packages

The newly implemented quantum‐chemical/molecular‐mechanical (QM/MM) functionality of the Groningen molecular simulation (GROMOS) software for (bio)molecular simulation is described. The implementation scheme is based on direct coupling of the GROMOS C++ software to executables of the quantum‐chemical program packages MNDO and TURBOMOLE, allowing for an independent further development of these packages. The new functions are validated for different test systems using program and model testing techniques. The effect of truncating the QM/MM electrostatic interactions at various QM/MM cutoff radii is discussed and the application of semiempirical versus density‐functional Hamiltonians for a solute molecule in aqueous solution is compared. © 2012 Wiley Periodicals, Inc.     

Tangential-flow ultrafiltration: a versatile methodology for determination of complexation parameters in refractory organic matter from Brazilian water and soil samples

In this work the copper(II) complexation parameters of aquatic organic matter, aquatic and soil humic substances from Brazilian were determined using a new versatile approach based on a single-stage tangential-flow ultrafiltration (TF-UF) technique (cut-off 1 kDa) and sensitive atomic spectrometry methods. The results regarding the copper(II) complexation capacity and conditional stability constants obtained for humic materials were compared with those obtained using direct potentiometry with a copper-ion-selective electrode. The analytical procedure based on ultrafiltration is a good alternative to determine the complexation parameters in natural organic material from aquatic and soil systems. This approach presents additional advantages such as better sensibility, applicability for multi-element capability, and its possible to be used under natural conditions when compared with the traditional ion-selective electrode.     

Feasibility of Ultrafast High‐Resolution Spectroscopy in the Analysis of Molecular‐Mobility‐Restricted Samples in Deuterium‐Free Environments

The feasibility of ultrafast high‐resolution intermolecular multiple‐quantum coherence (UF‐iMQC) spectroscopy for the direct analysis of molecular‐mobility‐restricted samples that are not suitable for magic‐angle spinning, such as a jelly, hand soap, and marrow, is presented. Most components could be directly detected in their original state within 1 min without the need for tedious sample preparation processes. When we use conventional liquid nuclear magnetic resonance (NMR) method to study these systems, the spectral information could not be retrieved owing to the intrinsic inhomogeneous magnetic fields caused by sample inhomogeneity. In addition, the possibility for UF‐iMQC‐based quantifications is shown. The examples presented in this paper demonstrate the potential of UF iMQC NMR for food safety inspection, for quality testing of daily‐life supplies, or in assisting medical diagnosis.     

Efficient and Selective Carboligation with Whole‐Cell Biocatalysts in Pickering Emulsion

Pickering emulsions (PEs) are particle‐stabilized multiphase systems with promising features for synthetic applications. Described here is a novel, simplified set‐up employing catalytically active whole cells for simultaneous emulsion stabilization and synthetic reaction. In the stereoselective carboligation of benzaldehyde to (R)‐benzoin catalyzed by a benzaldehyde lyase in E. coli, the set‐up yielded maximum substrate conversion within very short time, while economizing material demand and waste. Formation and activity of freshly produced PEs were enhanced when the catalytic whole cells were covered with hydrophobic silicone prior to PE formation. Benchmarked against other easy‐to‐handle whole‐cell biocatalysts in pure organic solvent, neat substrate, an aqueous emulsion in substrate, and a micro‐aquatic system, respectively, the cell‐stabilized PE outperformed all other systems by far.     

Voltammetric Determination of 4‐Nitrophenol and 5‐Nitrobenzimidazole Using Different Types of Silver Solid Amalgam Electrodes – A Comparative Study

The voltammetric behavior of two genotoxic nitro compounds (4‐nitrophenol and 5‐nitrobenzimidazole) has been investigated using direct current voltammetry (DCV) and differential pulse voltammetry (DPV) at a polished silver solid amalgam electrode (p‐AgSAE), a mercury meniscus modified silver solid amalgam electrode (m‐AgSAE), and a mercury film modified silver solid amalgam electrode (MF‐AgSAE). The optimum conditions have been evaluated for their determination in Britton‐Robinson buffer solutions. The limit of quantification (L_Q) for 5‐nitrobenzimidazole at p‐AgSAE was 0.77 µmol L^?1 (DCV) and 0.47 µmol L^?1 (DPV), at m‐AgSAE it was 0.32 µmol L^?1 (DCV) and 0.16 µmol L^?1 (DPV), and at MF‐AgSAE it was 0.97 µmol L^?1 (DCV) and 0.70 µmol L^?1 (DPV). For 4‐nitrophenol at p‐AgSAE, L_Q was 0.37 µmol L^?1 (DCV) and 0.32 µmol L^?1 (DPV), at m‐AgSAE it was 0.14 µmol L^?1 (DCV) and 0.1 µmol L^?1 (DPV), and at MF‐AgSAE, it was 0.87 µmol L^?1 (DCV) and 0.37 µmol L^?1 (DPV). Thorough comparative studies have shown that m‐AgSAE is the best sensor for voltammetric determination of the two model genotoxic compounds because it gives the lowest L_Q, is easier to prepare, and its surface can be easily renewed both chemically (by new amalgamation) and/or electrochemically (by imposition of cleaning pulses). The practical applicability of the newly developed methods was verified on model samples of drinking water.     

Isolated β‐Turn Model Systems Investigated by Combined IR/UV Spectroscopy

The functionality of bioactive molecules sensitively depends on their structure. For the investigation of intrinsic structural properties, molecular beam experiments combined with laser spectroscopy have proven to be a suitable tool. Herein we present an analysis of the two isolated tripeptide model systems Ac‐Phe‐Tyr(Me)‐NHMe and Boc‐Phe‐Tyr(Me)‐NHMe. For this purpose, mass‐selective combined IR/UV spectroscopy is applied to both substances in a molecular beam experiment. The comparison of the experimental data with DFT calculations, including different functionals as well as dispersion corrections, allows an assignment of both tripeptide models to β‐turns formed independently from the protection groups and supported by the interaction of the two aromatic chromophores.     

Tetracycline Removal Under Solar Illumination Over Ag3VO4/mpg‐C3N4 Heterojunction Photocatalysts

Ag₃VO₄/mpg‐C₃N₄ (mesoporous graphitic carbon nitride) heterojunction photocatalysts were prepared by anchoring tiny Ag₃VO₄ particles on the nanosheet of mpg‐C₃N₄. The prepared Ag₃VO₄/mpg‐C₃N₄ heterojunctions were used to remove tetracycline (TC), a kind of antibiotics widely released into the aquatic environment under solar irradiation. Compared with pure mpg‐C₃N₄ and Ag₃VO₄, Ag₃VO₄/mpg‐C₃N₄ displayed much higher photocatalytic activity (83.2% removal rate within 90 min under visible‐light irradiation). Importantly, no apparent deactivation was observed for Ag₃VO₄/mpg‐C₃N₄‐40 after five cycles, inferring a good reusability. As confirmed by photocurrent measurement and photoluminescence spectra, the excellent photocatalytic property of Ag₃VO₄/mpg‐C₃N₄ was credit to the electron–hole separation enhancement at the formed heterojunction of two semiconductors. In addition, a possible mechanism and intermediate products for the Ag₃VO₄/mpg‐C₃N₄ photocatalysts toward the photodegradation of TC in aqueous solution under artificial sunlight radiation were proposed based on the scavengers trapping test, ESR spectra and a high‐performance liquid chromatography (HPLC) coupled with mass spectrometer (MS) analysis. This investigation provides a low cost, green and easily practical approach to remove the antibiotics in the aquatic environment.     

Paper‐Based Ratiometric Fluorescence Analytical Devices towards Point‐of‐Care Testing of Human Serum Albumin

Monitoring of human serum albumin (HSA) in a point‐of‐care fashion is urgently needed in particular for elderly or chronically ill patients. Herein, a dual‐state emissive chalcone probe having the feature of aggregation‐induced emission was designed and synthesized. The concentration of HSA can be evaluated by the ratios of emission from probes in aggregated and monomeric state, which gives a visually discernible red‐to‐green color change. A simple, portable paper‐based analytical device have been fabricated by integration of the recognition probe in the detection pad and employed for HSA test using the whole blood samples. This paper‐based assay shows the analytical capability comparable to the standard testing methods but is in a point‐of‐care fashion, providing a promising tool for at‐home HSA detection and HSA‐related disease diagnosis.