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- Biofuels (3)
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Organisationseinheit der BAM
- 1 Analytische Chemie; Referenzmaterialien (2)
- 1.4 Prozessanalytik (2)
- 3 Gefahrgutumschließungen; Energiespeicher (1)
- 3.2 Gefahrguttanks und Unfallmechanik (1)
- 4 Material und Umwelt (1)
- 4.5 Kunst- und Kulturgutanalyse (1)
- 5 Werkstofftechnik (1)
- 5.6 Glas (1)
- 7 Bauwerkssicherheit (1)
- 7.6 Korrosion und Korrosionsschutz (1)
IR and Raman study of calcium aluminosilicate glasses of the composition xCaO.xAl2O3.(100-2x)SiO2
(2002)
Resistance to oxidative degradation by nitric acid has been selected for a comparison of polyethylene grades in a European standard on suitability proof for alternative plastic resins used for packagings and intermediate bulk containers (IBCs) for the transport of dangerous goods. Measurements of the infrared (IR) absorption spectra of microtome slices cut from the walls of jerricans, which were pre-stored with 55% nitric acid for 21 and 42 days at 40°C, showed changes in the structure of the polyethylene. The penetration depths of 55% nitric acid into the polyethylene grades are, in principle, suitable for evaluating the resistance to oxidative degradation of polyethylene grades after pre-storage of the packagings for 21 days. After this period the packaging wall is not fully penetrated. The intensities of the IR bands at 1565 cm-1 (-NO2), 1630 cm-1 (-C=C) and 1654 cm-1 (-O-NO2) increased with the treatment time with 55% nitric acid as a result of oxidative damage by the nitric acid. The high increase in absorbance of the -C=C band in the region 1630 - 1690 cm-1 is attributable to paraffinic chain cracks. The absorbance of the -O-NO2 band, formed as result of the nitration process was still low at a test temperature of 40°C.
There is a high international priority attached to activities which reduce NOx in the atmosphere. The current level of permitted emissions is typically between 50 µmol/mol and 100 µmol/mol, but lower values are expected in the future. Currently, ambient air quality monitoring regulations also require the measurement of NOx mole fractions as low as 0.2 µmol/mol. The production of accurate standards at these levels of mole fractions requires either dilution of a stable higher concentration gas standard or production by a dynamic technique, for example one based on permeation tubes.
The CCQM-K74 key comparison was designed to evaluate the level of comparability of National Metrology Institutes' measurement capabilities and standards for nitrogen dioxide (NO2) at a nominal mole fraction of 10 µmol/mol.
The measurements of this key comparison took place from June 2009 to May 2010.
Seventeen laboratories took part in this comparison coordinated by the BIPM and VSL. The key comparison reference value was based on BIPM measurement results, and the standard measurement uncertainty of the reference value was 0.042 µmol/mol.
This key comparison demonstrated that the results of the majority of the participants agreed within limits of ±3% relative to the reference value. The results of only one laboratory lay significantly outside these limits. Likewise this comparison made clear that a full interpretation of the results of the comparison needed to take into account the presence of nitric acid (in the range 100 nmol/mol to 350 nmol/mol) in the cylinders circulated as part of the comparison, as well as the possible presence of nitric acid in the primary standards used by participating laboratories.
Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.
The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).
DatesIssue 1A (Technical Supplement 2012)
This pilot study compares the performance of participants in analyzing gas mixtures of nitrogen dioxide in nitrogen by comparison with in-house gravimetric standards using Fourier transformed infrared spectroscopy (FT-IR). In this study the same gas mixtures were used as in the key comparison CCQM-K74, which was designed to evaluate the level of comparability of National Metrology Institutes' measurement capabilities for nitrogen dioxide (NO2) at a nominal mole fraction of 10 µmol/mol. In the comparison CCQM-K74 most of the participants used chemiluminescence, with a small number using UV absorption or FT-IR spectroscopy, and thus it is of interest to improve understanding of the comparative performance of these techniques because they do not exhibit any cross-sensitivity to nitric acid (HNO3), which was known to be present in the mixtures used for the comparison.
The results of this pilot study indicate good consistency and a level of agreement similar to that reported in the comparison CCQM-K74, demonstrating that FT-IR can be operated as a comparison method when calibrated with appropriate gas standards and can achieve similar measurement uncertainties to chemiluminescence and UV absorption techniques.
An additional pilot study, CCQM-P110-B2, was conducted on the same gas mixtures in parallel with this pilot study. The second study addressed FT-IR spectroscopy when used to measure the gas mixtures with respect to reference spectra. The results of this second study will be reported elsewhere.
Main text. To reach the main text of this paper, click on Final Report.
The final report has been peer-reviewed and approved for publication by the CCQM-GAWG.
DatesIssue 1A (Technical Supplement 2012)
Delta-Hexabromocyclododecane
(2007)
The suitability of an Al2O3 coating for corrosion protection on X20Cr13 was evaluated in various artificial geothermal brines, focusing on the influence of different pH (4, 6 and 8) and their chemical compositions on the coating properties. All experiments were performed in the laboratory using autoclaves at 150 ◦C and 1 MPa in deaerated condition for 1 and 7 days. Results showed that the pH of geothermal waters is the most detrimental factor in the transformation of ɣ-Al2O3 and its protective abilities. Delaminations were found in the Coating exposed to geothermal brines with pH 4. FTIR spectra indicated a transformation of ɣ-Al2O3 to boehmite AlOOH after exposure to pH 4 and 6, and bayerite Al(OH)3 was formed after exposure to pH 8. Different Crystal structures of the hydrated Al2O3 also contribute to the stability of the coatings, observed by the SEM- EDX of the surface and cross-section of coatings. This study indicated that ɣ-Al2O3 sol-gel coating presents a promising aspect of corrosion protection in geothermal environment with a neutral pH.
The assessment of quantification results of the alcohol abuse marker ethyl glucuronide (EtG) in hair in comparison to the cut-off values for the drinking behavior may be complicated by cosmetic hair bleaching. Thus, the impact of increasing exposure to hydrogen peroxide on the EtG content of hair was investigated. Simultaneously, the change of absorbance in the range of 1000–1100 cm-1 indicative for the oxidation of cystine was investigated non-destructively by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) using pulverized portions of the respective hair samples. Hair samples treated with hydrogen peroxide consistently displayed a significantly increased absorbance at 1040 cm-1 associated with the formation of cysteic acid. The EtG content decreased significantly if the hair was treated with alkaline hydrogen peroxide as during cosmetic bleaching. It could be shown that ATR-FTIR is capable of detecting an exposure to hydrogen peroxide when still no brightening was visible and already before the EtG content deteriorated significantly. Thus, hair samples suspected of having been exposed to oxidative treatment may be checked non-destructively by a readily available technique. This assay is also possible retrospectively after EtG extraction and using archived samples.