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Organisationseinheit der BAM
- 1.1 Anorganische Spurenanalytik (51) (entfernen)
Per- and polyfluorinated alkyl substances (PFASs) are a substance class of over 4730 individual compounds. Several PFASs are extremely persistent, bioaccumulative and toxic. The analysis of PFASs is challenging because of their different chemical and physical properties as well as the high number of target substances. Target-based approaches (e.g., LC-MS/MS) are limited to the availability of analytical grade standards and are not suitable for the analysis of new/unknown PFASs and transformation products. Therefore, PFAS sum parameter methods become increasingly important to indicate a realistic PFAS pollution level.
PFAS sum parameters compromise the proportion of organically bound fluorine that can either be extracted (EOF) or adsorbed to activated carbon (AOF). For the instrumental analysis of such sum parameters, a fluorine selective detector is needed. High resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) is a sensitive and highly selective tool for indirect fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) in a graphite furnace at a temperature of 1550°C. The molecular absorption of GaF can be detected at its most sensitive wavelength at 211.248 nm providing limits of quantification of c(F) 2.7 µg/L.
Here, we describe a fast and simple extraction method for the determination of the EOF using HR-CS-GFMAS in soil samples. Common approaches for the EOF determination use solid phase extraction (SPE). To omit the bias of this time consuming and expensive step we optimized a fast and simple SPE-free extraction method. The developed extraction method consists of a liquid-solid extraction using acidified methanol. Comparison of the method with and without an SPE clean-up step revealed a drastic underestimation of EOF concentrations using SPE. In the next step, the applicability of our method was tested for other solid matrices. In view of steadily increasing numbers of PFASs, our method will make an important contribution in assessing the pollution situation as well as support policy makers in deriving exposure limits for PFASs in the future.
Here, we describe a fast and simple extraction method for the determination of per- and polyfluorinated alkyl substances (PFASs) utilizing extractable organic fluorine (EOF) sum parameter analysis and high resolution-continuum source-graphite furnace molecular absorption spectrometry (HR-CS-GFMAS) in soil samples. After extraction and separation of inorganic and organic fluorinated compounds, organically bound fluorinated compounds were indirectly determined via the molecular absorption of gallium mono-fluoride at 211.248 nm. The implementation of the decisions of the “Stockholm Convention on persistent organic pollutants” as well as the “Protocol on Persistent Organic Pollutants of the Convention on Long-Range Transboundary Air Pollution” of the UNECE include the reduction respectively the elimination of PFASs in the environment. Currently, regulations aim to target single compounds (mostly C8-PFAS). But the PFAS group includes over 4700 substances, which are potentially persistent and toxic, thus target analytical approaches are not suitable for a holistic approach investigating the PFAS pollutant situation. Furthermore, forbidden PFASs are substituted by short-chain PFASs, thus the number of unknow substances is steadily increasing. For this reason, sum parameter approaches are more suitable to investigate and assess the pollution situation as well as derive exposure limits. Our developed analytical method was successfully applied to determine PFASs in soil samples from a polluted site. In view of steadily increasing numbers of PFAS substances, our method will make an important contribution in assessing the pollution situation as well as support policy makers in deriving exposure limits for PFAS in the future.
For the first time polyethylene (PE) frits were used to quantify sulphur in copper metal and its alloys by isotope dilution combined with LA-ICP-MS: an alternative approach for sample preparation. The properties of the PE frit meet the requirements for isotope dilution LA-ICPMS which are porous material, thermal and chemical resistance and high absorption efficiency. The breakthrough, however, as a support material, is the low sulphur blank, which is only two times of the gas flow blank (2.3-4.0 x 10⁴ cps). Additionally, the porosity of the frit was considered, as it directly affects the absorption efficiency for the sample solution, which is present in the cavities of the frit.
The absorption efficiency was studied by loading sulphur standards with varying sulphur amounts (0 - 80 µg S) onto the frits. The remaining sulphur which was not absorbed by the frit was rinsed off and was measured by ICP-MS. This indirect method shows that more than 99.5 % of the loaded sulphur was absorbed by the frit. The so prepared frits with increasing sulphur amount were measured by LA-ICP-MS showing a good linearity between 0 µg S and 40 µg S with a coefficient of determination, r2 of 0.9987 and a sensitivity of 3.4x10⁴ cps µgˉ¹ for 32S.
Three copper reference materials produced by BAM (BAM-M376a, BAM-228 and BAM-227) were selected to develop and validate the LA-ICP-IDMS procedure. The IDMS technique was applied to these samples as follows: the samples were spiked, dissolved, digested and then the digested solution was absorbed on the frits. The dried frit samples were then analyzed by LA-ICP-IDMS and it could be demonstrated that the sample solution dispersed on the frits did not influence the 32S/34S ratio significantly even though the sulphur intensities were fluctuating along the scan lines. Relative standard deviations of the isotope ratios were below 5 % in average between 3 lines (except for the pure spike solution and procedure blank). The measurement results were validated by comparing them with the results obtained by conventional ICP-IDMS. Plotting the mass fraction of sulphur in copper obtained by LA-ICP-IDMS versus those obtained by ICP-IDMS yields a linear curve with a correlation coefficient of 0.9999 showing a strong agreement between both techniques.
The metrological traceability to the SI for the mass fraction of sulphur in copper is established by an unbroken chain of comparisons, each accompanied by an uncertainty budget. Thus, the measurement results are considered reliable, acceptable and comparable within the stated measurement uncertainty. The metrological traceability chain from the kg down to the final mass fraction in the samples obtained by LA-ICP-IDMS is illustrated in this presentation.
Iron isotopes are used in a variety of fields from e.g., geologic question to medical applications. Measurements of iron isotopes are usually performed as delta measurements to an artificial based delta zero standard. In the case of Fe isotopes is that delta zero standard IRMM-014, a pure Fe metal. Unfortunately, that conventional delta zero reference material defining the 56/54Fe scale is out of stock and therefore unavailable. To overcome that situation and fulfill the need for laboratories that measure Fe isotope on a regular basis we will provide a set of solutions with IRMM-014 and a second anchor point for Fe isotope ratio measurements that is based on a pure Fe metal. This new second anchor point, a high purity Fe from BAM, will be calibrated against IRMM-014 and can be used as bracketing standard or as reference value for stable Fe isotope measurements.
We are in the good situation that BAM ordered a large stock of IRMM-014 several years ago. That stock of IRMM-014 Fe cubes and IRMM-014 Fe wires will be dissolved in 6M HCl in a large quantity. The new anchor point, the high purity Fe metal, that is commercially available at BAM, is a pure Fe metal with only trace amounts of impurities. The high purity BAM material will also be dissolved in 6M HCl in large quantity. Several aliquots of both solutions will be measured on the Neptune Plus MC-ICP-MS to define this second anchor point with a low uncertainty. Further will we send several aliquots of both solutions to different laboratories to also measure this second anchor point of high purity Fe on the 56/54Fe scale.
We will report the values of that study on BAM high purity Fe and will provide a guide for scale conversion to the IRMM-014 scale and for uncertainty calculation to use that new anchor point instead of the exhausted IRMM-014.
HR-CS-GFMAS turned out to be a sensitive, fast and highly selective tool for fluorine determination. The method is based on the in situ formation of diatomic gallium-mono fluoride (GaF) at a temperature of 1550°C. GaF can be detected at 211.248 nm providing limits of quantificationin the low μg/L range. However, several species specific effects where observed when analyzing PFASs.
In the past, δ26/24Mg measurements were referenced to NIST SRM 980, the initial zero of the δ26/24Mg scale. With the development of MC-ICPMS, the detection of small but measurable isotopic differences in different chips of SRM 980 became apparent. To solve this problem a suite of magnesium isotope reference materials, ERM-AE143, -AE144 and -AE145, has been certified in a first study by applying an ab initio calibration for absolute Mg isotope ratios without any a priori assumptions, a procedure which fulfils all requirements of a primary method of measurement. We could achieve for the first time measurement uncertainties for isotope amount ratios close to the typical precision of magnesium delta values, δ26/24Mg, which are at the 0.1 ‰ level (2SD). In addition, it was demonstrated that commonly used fractionation laws are invalid for correcting Mg isotope ratios in multi-collector ICPMS as they result in a bias which is not covered by its associated uncertainty. Depending on their type, fractionation laws create a bias up to several per mil, with the exponential law showing the smallest bias between 0.1 ‰ to 0.7 ‰.
With these isotope reference materials, it is possible to establish SI-traceability for magnesium delta measurements. To realize this, we organized a second study within which five expert laboratories participated to cross-calibrate all available magnesium isotope standards, which are NIST SRM 980, IRMM-009, ERM-AE143, ERM-AE144, ERM-AE145 and the standards DSM3 and Cambridge-1. The mean δ26/24Mg values for the individual iRMs, calculated from the laboratory means show 2 SD reproducibilities varying between 0.025 and 0.093 ‰. Propagated measurement uncertainties suggest a standard uncertainty of about 0.1‰ for δ26/24Mg determinations (2SD). Thus, SI traceability for magnesium isotope amount ratios and delta values is demonstrated to be established.
In the past, δ26/24Mg measurements were referenced to NIST SRM 980, the initial zero of the δ26/24Mg scale. With the development of MC-ICPMS, the detection of small but measurable isotopic differences in different chips of SRM 980 became apparent. To solve this problem a suite of magnesium isotope reference materials, ERM-AE143, -AE144 and -AE145, has been certified in a first study by applying an ab initio calibration for absolute Mg isotope ratios without any a priori assumptions, a procedure which fulfils all requirements of a primary method of measurement. We could achieve for the first time measurement uncertainties for isotope amount ratios close to the typical precision of magnesium delta values, δ26/24Mg, which are at the 0.1 ‰ level (2SD). In addition, it was demonstrated that commonly used fractionation laws are invalid for correcting Mg isotope ratios in multi-collector ICPMS as they result in a bias which is not covered by its associated uncertainty. Depending on their type, fractionation laws create a bias up to several per mil, with the exponential law showing the smallest bias between 0.1 ‰ to 0.7 ‰.
With these isotope reference materials, it is possible to establish SI-traceability for magnesium delta measurements. To realize this, we organized a second study within which five expert laboratories participated to cross-calibrate all available magnesium isotope standards, which are NIST SRM 980, IRMM-009, ERM-AE143, ERM-AE144, ERM-AE145 and the standards DSM3 and Cambridge-1. The mean δ26/24Mg values for the individual iRMs, calculated from the laboratory means show 2 SD reproducibilities varying between 0.025 and 0.093 ‰. Propagated measurement uncertainties suggest a standard uncertainty of about 0.1‰ for δ26/24Mg determinations (2SD). Thus, SI traceability for magnesium isotope amount ratios and delta values is demonstrated to be established.
Nearly all disease processes are associated with variations of components of the extracellular matrix (ECM) that are typically observed during the development of inflammation. This concerns for example proteoglycans and their associated glycosaminoglycans (GAG), which have been shown to bind to cationic metal imaging probes due to their strong complexing activity. The complexing activity largely depends on the degree of GAG sulfation and/or carboxylation as well as on the GAG isomericity. In this central project, we investigate GAG structures from inflammatory disorders (namely cardiovascular diseases, inflammatory intestinal diseases and neuroinflammation) provided by researchers of the Collaborative Research Center at the molecular disaccharidic level using chromatographic and mass spectrometric methods. In parallel, the spatial localization and quantification of metal-based imaging probes are evaluated by LA-ICP-MS imaging.