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Paper des Monats
- ja (1)
The title compound [systematic name: (2R,3R,4S,5R,6R) 2-(acetoxymethyl)-6-propoxytetrahydro-2H-pyran-3,4,5-triyl triacetate], C17H26O10, was formed by a Koenigs-Knorr reaction of 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide and n-propanol. The central ring adopts a chair conformation. The crystal does not contain any significant interactions such as hydrogen bonds.
An interlaboratory comparison for the determination of aniline, nine methylated anilines and chlorinated anilines in contaminated groundwater (each compound between 1 µg L-1 and 750 µg L-1) was conducted as proficiency test for the selection of contract laboratories for a groundwater monitoring campaign. For the 13 participants, two different test sample series were prepared from a stabilized real case groundwater. Series A was the groundwater as sampled in the field and series B was prepared from series A by spiking with selected anilines. Homogeneity and stability investigations revealed that contaminated groundwater provides a viable basis for the preparation of ring test samples for the determination of anilines. Analytical procedures were limited to the standardized liquid–liquid extraction or solid-phase extraction in combination with gas chromatography/mass spectrometry (DIN 38407-16:1999). The robust consensus values were evaluated according to the standardized protocol of DIN 38402-45:2013. Robust reproducibility standard deviations ranged largely between 20?% and 60?% depending on the analyte. The proficiency assessment of individual participants combined the qualitative aspect of correct peak identification with the quantitative determination of individual concentrations within set limits in a unified approach. It could be shown that the accreditation status of laboratory and the existence of a standardized analytical procedure do not substitute a problem-related proficiency assessment of potential contractors.
The resource-saving utilisation of recovered
waste wood is a matter of growing concern. In several
European countries, this utilisation is governed by regulations
and is dependent on the contents of certain trace
elements and organic compounds. Thus, for decisionmaking
with respect to waste wood management (recycling
or combustion), reliable analytical data are needed and, due
to their great economic and environmental impact, must be
assured by appropriate quality control. To support the
improvement in quality assurance in waste wood analysis,
for the first time, a wood reference material was certified
for its mass fractions of arsenic, cadmium, chromium,
copper, lead, mercury, and pentachlorophenol (PCP).
These analytes were selected because they represent typical
constituents of wood preservatives most widely used in the
past. Material preparation and testing of homogeneity and
stability were carried out by BAM Federal Institute for
Materials Research and Testing. The certification measurements
were performed involving selected laboratories
with documented expertise in the field of waste wood
analysis. The certified values and their corresponding
uncertainties were assigned in full compliance with the
requirements of ISO Guide 35. The certified mass fractions
and their expanded uncertainties (k/i> = 2) are as follows:
(3.1 ± 0.5) mg/kg for As, (3.02 ± 0.24) mg/kg for Cd,
(36.4 ± 2.6) mg/kg for Cr, (22.9 ± 1.7) mg/kg for Cu,
(0.60 ± 0.14) mg/kg for Hg, (39 ± 4) mg/kg for Pb, and
(7.9 ± 0.6) mg/kg for PCP. The certified material is
available as European Reference Material ERM®-CD100.
Technical 1,2,5,6,9,10-hexabromocyclododecane (HBCD) consists largely of three diastereomers (α-, β-, and γ-HBCD) produced by the trans addition of bromine to cis,trans,trans-cyclododeca-1,5,9-triene (CDT). However, another seven diastereomers are theoretically possible and may be produced by trans addition of bromine across the double bonds of the other three isomers of 1,5,9-CDT. There are indications that small amounts of the minor HBCD isomers may be present in commercial HBCD mixtures or in products containing this brominated flame retardant (BFR). Such minor components may indeed derive from traces of other 1,5,9-CDTs in the cis, trans, trans starting material, however their formation may also be possible through isomerizations during the processing of this BFR or by bioisomerization subsequent to its release into the environment. Two of the seven additional diastereomers (δ- and ε-HBCD) were synthesized previously from trans,trans,trans-CDT. We now report the preparation of the remaining five diastereomers, ζ-, η-, and θ-HBCD from cis,cis,trans-CDT and ι- and κ-HBCD from cis,cis,cis-CDT, and their characterization by 1H NMR spectroscopy and X-ray crystallography. The availability of these further diastereomers of HBCD should aid in determining if the minor isomers are present in commercial samples of this BFR, in products containing HBCDs, or in environmental samples. We have also carried out an X-ray crystal structure determination on ε-HBCD, so that crystal structures are now available for all 10 HBCD diastereomers.
The performance of twelve laboratories with previously established proficiency in the determination of the mineral oil content in a fresh water sediment is described. The summation parameter total petrol hydrocarbon (TPH) is defined according to ISO 16703:2004 with regard to the sample preparation to be applied, the flame ionisation detection (FID) and the boiling range of C10C40 to be integrated. Comprehensive tests of homogeneity and stability have been carried out on the candidate material using appropriate models. The outcome of the study served as the basis for the certification of the candidate reference material as ERM-CC015a. The certified mass fraction is 1,820±130mgkg-1 and traceability was established by using an appropriate calibration standard certified for the mass fraction of C10C40. The interlaboratory scatter of measurement results in this exercise can largely be explained by the variability of the individual calibrations based on this common calibration standard.
Certified reference materials for organic contaminants in sewage sludge - a feasibility study
(2008)
As an answer to the re-evaluation of the European sludge directive, two novel reference materials for organic components in municipal sludge have been produced and test certified for AOX (absorbable organic halogens), PAH (polycyclic aromatic hydrocarbons), NPE (nonylphenol and nonylphenolethoxylates), DEHP (di(2-ethylhexyl)phthalate), bisphenol A, and BFR (brominated flame retardants). The materials were prepared from raw sludge without spiking or mixing of different sludges. The study demonstrated that the technique for the preparation of a suitable reference material, sufficiently homogenous and stable, and with concentration levels that answer the needs of the laboratories and the relevant authorities, can now be presented in detail. The results, furthermore, show there is a need for method validation and standardisation of the measurements of NPEs and certain BFR congeners, and that the development of the laboratory structure in Europe, with fewer and more specialised laboratories, might become a major obstacle when trying to find a sufficient number of laboratories being appropriately proficient for this kind of study in the future.
The X-ray crystallographic study of the macrocyclic tetrakis-N[N-2-hydroxyethyl-piperazino]calix[4]resorcinarene·3CH3CH2OH·H2O (3) reveals a self-assembled dimeric capsule-like complex held together by an array of intermolecular hydrogen bonds. Pairs of concave molecules associate directly in bowl-to-bowl fashion and enclose an accessible supramolecular cavity of Å3 hosting one water and three ethanol molecules. The supramolecular arrangement displays alternating layers of facing bowls and interlocking lower rim aliphatic moieties. The helical conformation of the 2-hydroxyethyl piperazinomethyl moieties displays chirality of a bimolecular capsule frozen in the solid state. 3 crystallises in the triclinic space group P-1 with two symmetry independent molecules in the asymmetric unit. Two enantiomeric capsules form a racemic pair in the unit cell.
Delta-Hexabromocyclododecane
(2007)
The ecotoxicological characterization of waste is part of its assessment as hazardous or non-hazardous according to the European Waste List. For this classification 15 hazard criteria are derived from the Council Directive 91/689/EEC on hazardous waste. Some of the hazard criteria are based on the content of dangerous substances. The criterion H14 'ecotoxic' lacks of an assessment and testing strategy and no specific threshold values have been defined so far. Based on the recommendations of CEN guideline 14735 (2005), an international round robin test (ring test) was organized by the German Federal Environment Agency in order to define suitable test methods for the biological assessment of waste and waste eluates. A basic test battery, consisting of three aquatic and three terrestrial tests, was compiled. In addition, data were submitted for ten additional tests (five aquatic (including a genotoxicity test) and five terrestrial ones). The tests were performed with three representative waste types: an ash from an incineration plant, a soil containing high concentrations of organic contaminants (polycyclic aromatic hydrocarbons) and a preserved wood waste. The results of this ring test confirm that a combination of a battery of biological tests and chemical residual analysis is needed for an ecotoxicological characterization of wastes. With small modifications the basic test battery is considered to be well suitable for the hazard and risk assessment of wastes and waste eluates. All results and documents are accessible via a web-based data bank application.
Phosphorus recycling from sewage sludge will be obligatory in Germany from 2029. Phosphorus content determination in sewage sludge is crucial to assess the prescribed recycling rates. Currently, German law regards sample preparation using aqua regia digestion in a microwave or under reflux conditions as well as instrumental phosphorus determination by ICP-OES, ICP-MS, or photometric determination with ammonium molybdate as equivalent. However, it is questionable whether these methods are indeed equivalent regarding phosphorus quantification in sludges near the limit of 20 g/kg for mandatory recycling. To answer this question, 15 sewage sludges of 11 different wastewater treatment plants were investigated with all permitted method (digestion and measurement) combinations. Moreover, one sewage sludge was also examined in an interlaboratory comparison (ILC) with 28 participants. This study shows that the above-mentioned methods differ in some cases significantly but across all method combinations and sludges, phosphorus recovery was between 80 and 121% after normalization to the grand mean (average of 15 sludges between 85 and 111%). The ILC and the examination of 15 sludges produced largely similar results. There is a tendency to higher phosphorus recovery after microwave digestion compared to reflux digestion and ICP-OES measurements determine higher phosphorus contents than ICP-MS and photometric phosphorus determination. As a result, the authors recommend ICP-OES determination of phosphorus in sewage sludge after microwave digestion.
The statistical tool eCerto was developed for the evaluation of measurement data to assign property values and associated uncertainties of reference materials. The analysis is based on collaborative studies of expert laboratories and was implemented using the R software environment. Emphasis was put on comparability of eCerto with SoftCRM, a statistical tool based on the certification strategy of the former Community Bureau of Reference. Additionally, special attention was directed towards easy usability from data collection through processing, archiving, and reporting. While the effects of outlier removal can be flexibly explored, eCerto always retains the original data set and any manipulation such as outlier removal is (graphically and tabularly) documented adequately in the report. As a major reference materials producer, the Bundesanstalt für Materialforschung und -prüfung (BAM) developed and will maintain a tool to meet the needs of modern data processing, documentation requirements, and emerging fields of RM activity. The main features of eCerto are discussed using previously certified reference materials.
Microplastics can affect biophysical properties of the soil. However, little is known about the cascade of events in fundamental levels of terrestrial ecosystems, i.e., starting with the changes in soil abiotic properties and propagating across the various components of soil−plant interactions, including soil microbial communities and plant traits. We investigated here the effects of six different microplastics (polyester fibers, polyamide beads, and four fragment types: polyethylene, polyester terephthalate, polypropylene, and polystyrene) on a broad suite of proxies for soil health and performance of spring onion (Allium fistulosum). Significant changes were observed in plant biomass, tissue elemental composition, root traits, and soil microbial activities. These plant and soil responses to microplastic exposure were used to propose a causal model for the mechanism of the effects. Impacts were dependent on particle type, i.e., microplastics with a shape similar to other natural soil particles elicited smaller differences from control. Changes in soil structure and water dynamics may explain the observed results in which polyester fibers and polyamide beads triggered the most pronounced impacts on plant traits and function. The findings reported here imply that the pervasive microplastic contamination in soil may have consequences for plant performance and thus for agroecosystems and terrestrial biodiversity.
Three chromatographic procedures were investigated regarding their potential for the quantification of aniline and 19 of its methylated and chlorinated derivatives in groundwater. These methods were based on liquid-liquid-extraction in combination with gas chromatography and single quadrupole mass spectrometry (GC/MS) according to German standard DIN 38407-16:1999 and its extension using tandem mass spectrometry (GC/MS-MS), both following liquid-liquid extraction, and as third alternative the direct injection of the water sample into a liquid chromatograph coupled to tandem mass spectrometry (LC/MS-MS). Results were compared using fortified water and real-world contaminated groundwater used in an interlaboratory comparison. It could be shown that GC/MS and GC/MS-MS yielded results deviating less than 10% from each other while all three procedure displayed quantification results deviating less than 15% from the intercomparison reference values in case of each analyte in the concentration range between 1 and 45 µg L-1. Though GC/MS-MS displays a ten-fold higher sensitivity than single quadrupole GC/MS, the precision of both methods in the concentration range was similar. LC/MS-MS has the advantage of no further sample preparation due to the direct injection and leads for methylanilines and meta-, para- substituted chloroanilines to results sufficiently equivalent to the standardised GC/MS method. However, LC/MS-MS is not suitable for ortho-chloroaniline derivates due to significantly lower ion yields than meta- and para-substituted chloroanilines.
Stir bar sorptive extraction (SBSE) was compared with standardized pump sampling regarding the prospects to assess airborne levels of polycyclic aromatic hydrocarbons (PAHs) in indoor environments. A historic railway water tower, which will be preserved as a technical monument for museum purposes, was sampled with both approaches because the built-in insulationmaterial was suspected to release PAHs to the indoor air. The 16 PAHs on the US EPA list were quantified using gas chromatography with mass spectrometric detection in filters from pump sampling after solvent extraction and on SBSE devices after thermal desorption. SBSEwas seen to sample detectable PAHmasseswith excellent repeatability and a congener pattern largely similar to that observed with pump sampling. Congener patterns were however significantly different from that in the PAH source because release from the insulation material is largely triggered by the respective congener vapor pressures. Absolute masses in the ng range sampled by SBSE corresponded to airborne concentrations in the ng L−1 range determined by pump sampling. Principle differences between SBSE and pump sampling as well as prospects of SBSE as cost-effective and versatile complement of pump sampling are discussed.
Evidence for the formation of difluoroacetic acid in chlorofluorocarbon-contaminated ground water
(2019)
The concentrations of difluoroacetic acid (DFA) and trifluoroacetic acid (TFA) in rainwater and surface water from Berlin, Germany resembled those reported for similar urban areas, and the TFA/DFA ratio in rainwater of 10:1 was in accordance with the literature. In contrast, nearby ground water historically contaminated with 1,1,2-trichloro-1,2,2-trifluoroethane (R113) displayed a TFA/DFA ratio of 1:3. This observation is discussed versus the inventory of microbial Degradation products present in this ground water along with the parent R113 itself. A microbial Transformation of chlorotrifluoroethylene (R1113) to DFA so far has not been reported for environmental media, and is suggested based on well-established mammalian metabolic pathways.
Odor Perception by Dogs: Evaluating Two Training Approaches for Odor Learning of Sniffer Dogs
(2017)
In this study, a standardized experimental set-up with various combinations of herbs as odor sources was designed. Two training approaches for sniffer dogs were compared; first, Training with a pure reference odor, and second, training with a variety of odor mixtures with the target odor as a common denominator. The ability of the dogs to identify the target odor in a new context was tested. Six different herbs (basil, St. John’s wort, dandelion, marjoram, parsley, ribwort) were chosen to produce reference materials in various mixtures with (positive) and without (negative)chamomile as the target odor source. The dogs were trained to show 1 of 2 different behaviors, 1 for the positive, and 1 for the negative sample as a yes/no task. Tests were double blind with one sample presented at a time. In both training approaches, dogs were able to detect chamomile as the target odor in any presented mixture with an average sensitivity of 72% and a specificity of 84%. Dogs trained with odor mixture containing the target odor had more correct indications in the transfer task.
The concentration of contaminants in groundwater samples can be decreased by degradation in the time course between field sampling and quantification in the laboratory, especially in samples from sites where degradation activity is enhanced by remediation measures. The sampling sites covered a variety of priority organic pollutants such as volatile aromatic and chlorinated compounds, phenols and petroleum hydrocarbons and different remediation strategies such as anaerobic and aerobic microbial in situ degradation, in situ chemical oxidation, and on-site purification with biological treatment. The stability of the contaminants' concentration was investigated over a time range of several hours without cooling in the autosampler of the analytical equipment (short term) and over several days of storage until analysis (long term). A number of stabilisation techniques suggested in international standards ISO 5667-3:2013 and ASTM D6517:2000 were compared both with regard to short term and long term stabilisation of the contaminants and their practicability for field sampling campaigns. Long term storage turned out to be problematic for most compound groups even under cooling. Short term stability was problematic also for volatiles such as benzenic aromates, naphthalene and volatile organic halogenated compounds to be analysed by headspace gas chromatography. Acidification (pH <2) was sufficient to prevent degradation of benzenic aromates, naphthalene, phenols and petrol hydrocarbons for up to seven days. The use of acids was not applicable to stabilise volatiles in waters rich in carbonates and sulphides due to stripping of the volatiles with the liberated gases. The addition of sodium azide was successfully used for stabilisation of volatile organic halogenated compounds.