TY - JOUR A1 - Scholz, Philipp A1 - Wachtendorf, Volker A1 - Elert, Anna Maria A1 - Falkenhagen, Jana A1 - Becker, Roland A1 - Hoffmann, Katrin A1 - Resch-Genger, Ute A1 - Tschiche, Harald A1 - Reinsch, Stefan A1 - Weidner, Steffen ED - Scholz, Philipp T1 - Analytical toolset to characterize polyurethanes after exposure to artificial weathering under systematically varied moisture conditions JF - Polymer Testing N2 - Polyether and -ester urethanes (PU) were exposed to artificial weathering at 40 °C and artificial UV radiation in a weathering chamber. In 3 parallel exposures, humidity was varied between dry, humid, and wet conditions. Material alteration was investigated by various analytical techniques like size exclusion chromatography (SEC), liquid chromatography-infrared spectroscopy (LC-FTIR), thermal-desorption gas chromatography-mass spectrometry (TD-GC-MS), fluorescence mapping and dynamic mechanical analysis (DMA). Our results show that depending on the weathering conditions, different degradation effects can be observed. By means of SEC an initial strong decrease of the molar masses and a broadening of the mass distributions was found. After a material dependent time span this was followed by a plateau where molar mass changes were less significant. A minor moisture-dependent degradation effect was only found for polyester PU. Fluorescence measurements on two materials revealed an increase in the luminescence intensity upon weathering process reaching a saturation level after about 500 h. The changes in the optical properties observed after different exposure conditions and times were very similar. The TD-GC-MS data showed the fate of the stabilizers and antioxidant in the course of weathering. LC-FTIR measurements revealed a change in peak intensities and the ratio of urethane and carbonyl bands. KW - Polyurethane KW - Artificial weathering KW - Moisture KW - Crosslinking KW - Degradation PY - 2019 UR - https://www.sciencedirect.com/science/article/pii/S0142941819303708 DO - https://doi.org/10.1016/j.polymertesting.2019.105996 SN - 0142-9418 VL - 78 SP - 105996, 1 EP - 9 PB - Elsevier CY - Amsterdam AN - OPUS4-48625 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Esslinger, Susanne A1 - Becker, Roland A1 - Maul, Ronald A1 - Nehls, Irene T1 - Hexabromocyclododecane enantiomers: microsomal degradation and patterns of hydroxylated metabolites JF - Environmental science & technology N2 - The degradation of the enantiomers of α-, β-, and γ-hexabromocyclododecane (HBCD) by phase I metabolism was investigated using induced rat liver microsomes. HBCD isomers were quantified using HPLC-MS/MS (ESI-) after separation on a combination of a reversed phase and a chiral analytical column. The degradation of all six isomers followed first-order kinetics and the estimated half-lives ranged from 6.3 min for both β-HBCD enantiomers to 32.3 min in case of (+)-γ-HBCD. (+)-α- and (–)-γ-HBCD displayed significantly shorter half-lives than their corresponding antipodes. It could be shown that this degradation led to a significant enrichment of the first eluting enantiomers (–)-α- and (+)-γ-HBCD. Individual patterns of mono- and dihydroxylated derivatives obtained from each α- and γ-HBCD enantiomer were seen to be distinctly characteristic. The patterns of monohydroxylated HBCD derivatives detected in liver and muscle tissues of pollack, mackerel and in herring gull eggs were largely similar to those observed in the in vitro experiments with rat liver microsomes. This enabled individual hydroxy-HBCDs to be assigned to their respective parent HBCD enantiomers. KW - Brominated flame retardant KW - Cytochromes KW - Phase I metabolism KW - Hydroxylation KW - HPLC-MS/MS PY - 2011 DO - https://doi.org/10.1021/es1039584 SN - 0013-936X SN - 1520-5851 VL - 45 IS - 9 SP - 3938 EP - 3944 PB - ACS Publ. CY - Washington, DC AN - OPUS4-23837 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schallschmidt, Kristin A1 - Becker, Roland A1 - Jung, Christian A1 - Bremser, Wolfram A1 - Nehls, Irene A1 - Leschber, G. A1 - Frese, S. A1 - Walles, T. A1 - Neudecker, J. T1 - Comparison of volatile organic compounds from lung cancer patients and healthy controls—challenges and limitations of an observational study JF - Journal of Breath Research N2 - The design and operation of an observational study on the profiles of volatile organic compounds (VOC) in the breath of 37 lung cancer patients and 23 healthy controls of similar age is outlined. The necessity to quantify each VOC considered as potential disease marker on basis of individual calibration is elaborated and the quality control measures required to maintain reproducibility in breath sampling and subsequent instrumental trace VOC analysis using SPME-GC-MS over a study period of 14 months are described. 24 VOC were quantified on basis of their previously suggested potential as cancer markers. The breath concentration levels of aromatic compounds was expectedly increased in smokers while lung cancer patients displayed significantly increased levels of oxygenated VOC such as aldehydes, 2-butanone and 1-butanol. Though sets of selected oxygenated VOC displayed sensitivities and specificities between 80 and 90% using linear discriminant analysis with leave-one-out cross validation the effective selectivity of the breath VOC approach with regard to cancer detection is clearly limited. Results were discussed against the background of the literature on volatile cancer marker investigations and the prospects to link increased VOC levels in patients’ breath with approaches to employ sniffer dogs. Experiences from this study and the literature suggest that the current state of breath VOC based discrimination between cancer patients and healthy controls is hardly improvable. Observational studies tend to observe significant differences mostly in levels of certain oxygenated VOC but without resolution required for practical application. Any step towards practicable exploitation of VOC profile differences for illness detection would have to solve current restrictions set by the low and variable VOC concentrations. Further challenges are the technical complexity of studies involving breath sampling and possibly the limited capability of current analytical procedures to detect instable marker candidates. KW - Breath KW - Volatile organic compounds KW - Marker KW - Cancer KW - Gas chromatography KW - Solid phase microextraction KW - Volatilome PY - 2016 DO - https://doi.org/10.1088/1752-7155/10/4/046007 SN - 1752-7155 SN - 1752-7163 VL - 10 IS - 4 SP - Article 046007, 1 EP - 17 PB - IOP Publishing AN - OPUS4-37801 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Esslinger, Susanne A1 - Becker, Roland A1 - Müller-Belecke, A. A1 - Bremser, Wolfram A1 - Jung, Christian A1 - Nehls, Irene T1 - HBCD stereoisomer pattern in mirror carps following dietary exposure to pure Gamma-HBCD enantiomers JF - Journal of agricultural and food chemistry KW - Enantiomer-specific determination KW - HPLC-MS/MS KW - Brominated flame retardant KW - Fish feeding experiment KW - Enantiomer fraction KW - Bioisomerization PY - 2010 DO - https://doi.org/10.1021/jf101469q SN - 0021-8561 SN - 1520-5118 VL - 58 IS - 17 SP - 9705 EP - 9710 PB - American Chemical Society CY - Columbus, Ohio AN - OPUS4-23173 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reck, Günter A1 - Becker, Roland T1 - Bis­[N-n-butyl-N-(3,5-di-tert-butyl-2-hydroxy­benzyl)­di­thio­carbamato-Kappa²S,S']zinc(II) JF - Acta crystallographica E N2 - Both zinc di­thio­carbamates and sterically hindered phenols are known to exhibit antioxidant activity. As part of an investigation on the effect of both moieties being combined in one mol­ecule, the title compound, [Zn(C17H26NOS2)2], has been prepared and its crystal structure determined. PY - 2003 DO - https://doi.org/10.1107/S1600536803007372 SN - 1600-5368 VL - 59 IS - 5 SP - m234 EP - m235 PB - Munksgaard CY - Copenhagen AN - OPUS4-2464 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Becker, Roland A1 - Koch, Matthias A1 - Wachholz, Sigrid A1 - Win, Tin T1 - Quantification of total petrol hydrocarbons (TPH) in soil by IR-spectrometry and gas chromatography - conclusions from three proficiency testing rounds JF - Accreditation and quality assurance N2 - Due to the utilisation of 1,1,2-trichlorotrifluoroethane (CFE) as extraction solvent the IR-spectrometric determination of total petrol hydrocarbon (TPH) in soil according to ISO/TR 11046 has been replaced by gas chromatography/flame ionisation detection (GC/FID) after extraction with a halogen-free solvent according to ISO/DIS 16703:2001. The results obtained with both methods by field laboratories in three proficiency testing (PT) rounds are compared. The consensus means obtained with GC/FID are typically 10%-20% (ranging between 0% and 25%) higher than those found with IR-spectroscopy. On the contrary, coefficients of variation (CV) are roughly double in case of GC/FID and are briefly discussed against the background of the Horwitz equation. KW - Hydrocarbons KW - Soil KW - IR spectrometry KW - Gas chromatography KW - Interlaboratory comparison PY - 2002 DO - https://doi.org/10.1007/s00769-002-0476-9 SN - 0949-1775 SN - 1432-0517 VL - 7 IS - 7 SP - 286 EP - 289 PB - Springer CY - Berlin AN - OPUS4-1627 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Becker, Roland A1 - Buge, Hans-Gerhard A1 - Win, Tin T1 - Determination of pentachlorphenol (PCP) in waste wood - method comparison by a collaborative trial JF - Chemosphere N2 - Two independently developed and validated procedures for the determination of pentachlorophenol (PCP) in waste wood were compared by means of a collaborative trial. Both methods foresee quantification of PCP by gas chromatography (GC-ECD) after acetylation and differ with regard to the use of methanol or toluene/sulphuric acid, respectively, as solvent in the sonication extraction step. Test samples with established analyte homogeneity were prepared from a ground “real life” starting material. A total of 23 participating laboratories with experience in wood preservative analysis were instructed to apply both methods to three levels of content in the range of 0.5–20 mg PCP/kg. In case of the toluene/sulphuric acid extraction, lower recoveries and higher interlaboratory dispersion of results at the higher PCP contents were observed. Seen against the background of the Horwitz equation a reproducibility standard deviation of not, vert, similar19% for the methanol extraction at the 4.5 mg/kg level meets the requirement for a sound analytical method. Thus, the sonication extraction procedure with methanol has been annexed as a reference method to the German waste wood regulation. KW - Extraction KW - Derivatisation KW - Sonication KW - Analysis KW - Gas chromatography KW - Regulation PY - 2002 DO - https://doi.org/10.1016/S0045-6535(02)00004-8 SN - 0045-6535 SN - 0366-7111 VL - 47 SP - 1001 EP - 1006 PB - Elsevier Science CY - Kidlington, Oxford AN - OPUS4-1628 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reck, Günter A1 - Becker, Roland T1 - Phenanthroline complexes of zinc and calcium carbamates JF - Acta crystallographica C N2 - Bis(N,N-di-n-butyl­di­thio­carbamato-?2S,S')(1,10-phenanthroline-?2N,N')­zinc(II) ethanol hemisolvate, [Zn(C9H18NS2)2(C12H8N2)]·0.5C2H6O, (I), and bis(N,N-di-n-hexyldithiocarbamato-?2S,S')­bis(1,10-phenanthroline-?2N,N')calcium(II), [Ca(C13H26NS2)2(C12H8N2)2], (II), are mixed-ligand com­plexes. In the first compound, the Zn atom has a distorted octahedral coordination, while in the second compound, the Ca atom is eight-coordinate, with four S and four N atoms forming a highly distorted cube. KW - X-ray structure analyses KW - Metal-organic complexes KW - Antioxidant properties PY - 2004 DO - https://doi.org/10.1107/S0108270104001441 SN - 0108-2701 SN - 1600-5759 VL - 60 SP - m134 EP - m136 PB - Blackwell Publ. CY - Oxford AN - OPUS4-3110 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Becker, Roland A1 - Nehls, Irene A1 - Dorgerloh, Ute T1 - Interlaboratory comparisons - demonstrating degree of equivalence JF - Accreditation and quality assurance N2 - The role of matrix reference materials in the process of demonstrating the degree of equivalence of measurement results obtained from intercomparisons is outlined, reviewing exemplary selected experience gained at BAM regarding the determination of organic contaminants in environmental matrices. The specific characteristics of reference materials employed in the process of demonstrating equivalence between laboratories in the course of proficiency testing as well as the development, comparison and validation of methods are elaborated. The demand is for series of appropriately characterised samples which are fit for the purpose and it is seen from representative examples that the utilisation of such tailor-made RM designed to tackle the specific need of an analytical problem dominates over certified matrix reference materials in this context. Concluding, the role of certified matrix reference materials in quality assurance is briefly looked at both from the user’s and providers’ points of view. KW - Certification KW - Equivalence KW - Method development KW - Proficiency testing KW - Reference materials PY - 2003 DO - https://doi.org/10.1007/s00769-003-0580-5 SN - 0949-1775 SN - 1432-0517 VL - 8 SP - 150 EP - 155 PB - Springer CY - Berlin AN - OPUS4-2848 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Reck, Günter A1 - Becker, Roland T1 - (N,N-Diiso­butyl­di­thio­carbamoyl­sulfinato)­zinc(II) JF - Acta crystallographica E N2 - Zinc di­alkyl di­thio­carbamoyl­sulfinates have been proposed as intermediates in the antioxidant action of the respective zinc di­alkyl di­thio­carbamate additives in hydro­carbon-based plastics and lubricants. As a model compound, zinc diiso­butyl di­thio­carbamoyl­sulfinate, [Zn(C9H18NO2S2)2], has been prepared and its crystal structure determined. PY - 2003 DO - https://doi.org/10.1107/S160053680301314X SN - 1600-5368 VL - 59 IS - 7 SP - m489 EP - m490 PB - Munksgaard CY - Copenhagen AN - OPUS4-2577 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -