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Eingeladener Vortrag
- nein (5)
Triple IDMS has been applied for the first time to the quantification of element concentrations. It has been compared with single and double IDMS obtained on the same sample set in order to evaluate the advantages and disadvantages of triple IDMS over single and double IDMS as an analytical reference procedure. The measurement results of single, double and triple IDMS are indistinguishable, considering rounding due to the individual measurement uncertainties. As expected, the relative expanded uncertainties (k = 2) achieved with double IDMS (0.08 %) are dramatically smaller than those obtained with single IDMS (1.4 %). Triple IDMS yields the smallest relative expanded uncertainties (k = 2, 0.077 %) unfortunately at the expense of a much higher workload. Nevertheless triple IDMS has the huge advantage that the isotope ratio of the spike does not need to be determined. Elements with high memory effects, highly enriched spikes or highest metrological requirements may be typical applications for triple IDMS.
Die Industrie nutzt die Borisotopenanalytik in nukleartechnischen Anwendungen. Umwelt- und Geowissenschaften identifizieren anhand der Borisotopenverhältnisse Kontaminationsquellen und charakterisieren Mischungs- und Fraktionsprozesse. In der Lebensmittelanalytik dient der Parameter dazu, Herkunft und Anbauweise von Obst und Gemüse herauszufinden. Seit kurzem gibt es dafür ein validiertes Verfahren und erste Referenzdaten.
Isotopic reference materials are essential to enable reliable and comparable isotope data. In the case of boron only a very limited number of such materials is available, thus preventing adequate quality control of measurement results and validation of analytical procedures. To address this situation a unique set of two boron isotope reference materials (ERM-AE102a and -AE104a) and three offset δ11B reference materials (ERM-AE120, -AE121 and -AE122) were produced and certified. The present article describes the production and certification procedure in detail. The isotopic composition of all the materials was adjusted by mixing boron parent solutions enriched in 10B or 11B with a boron parent solution having a natural isotopic composition under full gravimetric control. All parent solutions were analysed for their boron concentration as well as their boron isotopic composition by thermal ionisation mass spectrometry (TIMS) using isotope dilution as the calibration technique. For all five reference materials the isotopic composition obtained on the basis of the gravimetric data agreed very well with the isotopic composition obtained from different TIMS techniques. Stability and homogeneity studies that were performed showed no significant influence on the isotopic composition or on the related uncertainties. The three reference materials ERM-AE120, ERM-AE121 and ERM-AE122 are the first reference materials with natural δ11B values not equal to 0. The certified δ11B values are -20.2 for ERM-AE120, 19.9 for ERM-AE121 and 39.7 for ERM-AE122, each with an expanded uncertainty (k = 2) of 0.6. These materials were produced to cover about three-quarters of the known natural boron isotope variation. The 10B enriched isotope reference materials ERM-AE102a and ERM-AE104a were produced for industrial applications utilising 10B for neutron shielding purposes. The certified 10B isotope abundances are 0.29995 for ERM-AE102a and 0.31488 for ERM-AE104a with expanded uncertainties (k = 2) of 0.00027 and 0.00028, respectively. Together with the formerly certified ERM-AE101 and ERM-AE103 a unique set of four isotope reference materials and three offset δ11B reference materials for boron isotope determination are now available from European Reference Materials.