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Lead (Pb) isotope amount ratios are commonly used in applications ranging from archaeology and forensic sciences to terrestrial and extra-terrestrial geochemistry. Despite their utility and frequency of use, only three certified isotope amount ratio reference materials are currently available for Pb: NIST SRMs 981, 982 and 983. Because SRM 981 has a natural Pb isotopic composition, it is mainly used for correcting instrumental mass discrimination or fractionation. This means that, at present, there are no other certified isotope reference materials with natural Pb isotopic composition that could be used for validating or verifying an analytical procedure involving the measurement of Pb isotope amount ratios.
To fill this gap, two new reference materials, both certified for their Pb isotopic composition, have been produced together with a complete uncertainty assessment. These new reference materials offer SI traceability and an independent means of validating or verifying analytical procedures used to produce Pb isotope amount ratio measurements.
ERM-EB400 is a bronze material containing a nominal Pb mass fraction of 45 mg/kg. ERM-AE142 is a high purity solution of Pb with a nominal mass fraction of 100 mg/kg. Both materials have been specifically produced to assist analysts in verifying or validating their analytical procedures. Note that while one of these reference materials requires the chemical separation of Pb from its matrix (ERM-EB400), the other does not (ERM-AE142). Details on the certification of these isotope reference materials are provided in this report.
Isotope amount ratios (hereafter referred to as simply isotope ratios) are proving useful in an ever increasing array of applications that range from studies unravelling transport processes, to pinpointing the provenance of specific samples as well as trace element quantification by using isotope dilution mass spectrometry (IDMS). These expanding applications encompass fields as diverse as archaeology, food chemistry, forensic science, geochemistry, medicine and metrology. However, to be effective tools, the isotope ratio data must be reliable and traceable to enable the comparability of measurement.
The importance of traceability and comparability in isotope ratio analysis has already been recognized by the Inorganic Analysis Working Group (IAWG) within the CCQM. Three pilot studies have focused on the quality of isotope ratio determinations (P48 “U isotope ratios in urine”, P75 “stable isotopes in Methionine”, P105 “87Sr/86Sr in wine”). Moreover, isotope ratio measurements are fundamental to IDMS amount of substance determinations. For example, when Pb quantification using IDMS is undertaken, this requires the measurements of Pb isotope ratios. While the requirements for isotope ratio accuracy and precision in the case of of IDMS are generally quite modest, “absolute” Pb isotope ratio measurements for geochemical age dating and source rock characterization as well as forensic provenance and fingerprinting studies require Pb isotope ratio measurements of the highest quality. To support present and future CMCs on isotope ratio determinations, a Key Comparison was urgently needed. Therefore, it was decided at the IAWG meeting in Paris in April 2011 that a Key Comparison on the determination of Pb isotope ratios in a pure Pb solution and in a bronze sample should be organized and accompanied by a pilot study.
Measuring Pb isotope amount ratios in a pure Pb solution, while seemingly straight forward, rigorously tests the ability of analyst to correct for any instrumental effects (such as mass discrimination and blank correction) on the measured ratios. Pb, present in trace amounts in a metal matrix sample (e.g. Pb in bronze), provides a real world test of the whole chemical and instrumental procedure, from chemical separation and sample purification to analysis and subsequent correction of appropriate instrumental effects on the separated samples.
A suitable bronze material with a Pb mass fraction between 10 and 100 mg·kg-1 was available at BAM. A high purity solution of Pb with a mass fraction of approximately 100 mg·kg-1 was also available. By comparing the Pb isotope ratio results obtained for the bronze sample with the Pb isotope ratio results from the Pb solution, potential biases arising from the processing of the bronze sample could be effectively identified and separated from the instrumental effects arising from the measurement and data processing protocol.
Three petrol reference materials were certified for their total sulfur content in support of Directive 2003/17/EC of the European Parliament and of the European Council, which stipulates that petrol with a maximum S content of 10 mg/kg must be available in all member states by 2009. Commercially available petrol was obtained and filled into borosilicate ampoules without further treatment. Homogeneity of the materials was tested and no heterogeneity was detected for two of the materials, whereas minor heterogeneity was observed for the third material. Stability of the materials was tested for 8-12 months at 60 °C and no degradation was observed. Characterisation was based on isotope-dilution mass spectrometry (IDMS) applied as primary method of measurement by three European metrology institutes and certified values were assigned using all results. The certified uncertainties include contributions of (potential) heterogeneity, potential degradation as well as characterisation. The final assigned values are:
ERM-EF211: 48.8 ± 1.7 mg/kg
ERM-EF212: 20.2 ± 1.1 mg/kg
ERM-EF213: 9.1 ± 0.8 mg/kg
The materials are available from IRMM (ERM-EF211), LGC (ERM-EF212) and BAM (ERMEF213)
Certification report for the reference materials ERM-AE102a, -AE104a, -AE120, -AE121 and -AE122
(2010)
Isotope reference materials are essential to enable reliable and comparable isotope data. Besides the correction of mass fractionation or mass discrimination isotope reference materials are indispensible for validation and quality control of analytical procedures. This article describes the production and certification of a set of five isotope reference materials ERM-AE102a, 104a, AE120, 121 and 122, for boron isotope analysis. The isotopic composition of all materials has been adjusted by mixing boron mother solutions enriched in 10B or 11B with a boron mother solution having natural-like isotopic composition under full gravimetric control. All mother solutions have been analysed for their boron mass fraction as well as their boron isotopic composition by TIMS using IDMS as calibration technique. For all five reference materials the isotopic composition obtained on the basis of the gravimetric data agrees very well with the isotopic composition obtained from different TIMS techniques. Performed stability and homogeneity studies show no significant influence on the isotopic composition as well as on the related uncertainties.
The certified isotope abundances for 10B are 0.29995 (27) for ERM-AE102a and 0.31488 (28) for ERM-AE104a. The certified δ11B values are -20.2 (6) ‰ for ERM-AE120, 19.9(6) ‰ for ERM-AE121 and 39.7 (6) ‰ for ERM-AE122.
Together with the formerly certified ERM-AE101 and -AE103 a unique set of seven certified reference materials (CRM) for boron isotope analysis is now available from BAM.
Isotope reference materials are essential to enable reliable and comparable isotope data. Besides the correction of mass fractionation or mass discrimination, isotope reference materials are indispensible for validation and quality control of analytical procedures. This report describes the production and certification of two isotope reference materials, ERM-AE123 and ERM-AE124, for boron isotope analysis. The isotopic composition of ERM-AE123 is the unaltered natural-like isotopic composition of the base material. The isotopic composition of ERM-AE124 has been adjusted by mixing two boron stock solutions enriched in 10B and 11B respectively under full gravimetric control. All stock solutions have been prepared fully under gravimetrical control. The corresponding boron isotopic composition has been analysed by TIMS. For both reference materials the isotopic composition obtained on the basis of the gravimetric data agrees very well with the isotopic composition obtained by TIMS. The certified isotope abundances for 10B are 0.19832 (21) for ERM-AE123 and 0.96006 (6) for ERM-AE124. Together with the formerly certified ERM-AE101, -AE102a, -AE103, -AE104a, -AE120, -AE121 and AE122, a unique set of nine certified reference materials (CRM) for boron isotope analysis is now available from BAM covering a range for the 10B isotope amount fraction from 0.2 to 0.96 and for the δ11B value from -20 ‰ to +40 ‰.
Isotope dilution mass spectrometry often is applied for the quantification of platinum group elements in environmental and geological samples. In most cases, however, certified spike solutions offering complete uncertainty statements and SI-traceability are missing. This report describes the production and certification of two isotope reference materials, ERM-AE140 and ERM-AE141, serving as calibrated spike solutions for IDMS based quantification of Pd and Pt, respectively. Both materials were produced by dissolving highly enriched isotopes 106Pd and 194Pt and determining the mass fraction of 106Pd and 194Pt in the final solution by reverse IDMS. Two independent back-spikes were produced for each material from high purity Pd and Pt. Characterization measurements were carried out by MC-ICPMS. For ERM-AE140 the certified mass fractions are w(106Pd) = 20.24(5) mg/kg and w(Pd) = 20.54(5) mg/kg. For ERM-AE141 the certified mass fractions are w(194Pt) = 18.18(11) mg/kg and w(Pt) = 19.90(12) mg/kg. These values are traceable to the International System of Units (SI) in the shortest possible way.
Dieser Bericht beschreibt die Herstellung und Zertifizierung einer Cadmiumlösung mit natürlicher Isotopenzusammensetzung. Für das Isotopen-Referenzmaterial sind sowohl die Isotopenverhältnisse als auch Isotopenhäufigkeiten und die molare Masse von Cadmium zertifiziert. Die Unsicherheiten sind erweiterte Messunsicherheiten U = k.uc mit k = 2. Der Cadmium-Massenanteil in der Lösung wird als indikativer Wert angegeben mit einer erweiterten Messunsicherheit U = k.uc mit k = 4,5.
This Report describes the certification of the reference material antimony implanted in Si/SiO2 intended to be used for calibration of surface and near surface analytical methods. It describes the preparation, homogeneity measurements and the analytical work performed for the certification of both Areal density of antimony Atoms (retained dose) and the isotope amount Ratio as well as giving considerations on the stability of the material.
Dieser Bericht beschreibt die Zertifizierung von 3 synthetischen Isotopenmischungen aus natürlicher und angereicherter Borsäure. Diese Isotopen-ZRM liegen als konzentrierte, wäs-serige Borsäure-Lösungen vor und sind bezüglich ihrer Isotopenzusammensetzung zertifi¬ziert. Der Bor-Gesamtgehalt ist als Richtwert angegeben. Die Unsicherheiten sind erweiterte Messunsicherheiten mit k=2. Sie sind in Klammern angegeben und beziehen sich auf die letzten beiden Stellen. Die vorliegenden Isotopen-ZRM sind bezüglich ihrer Isotopenzu¬sam-mensetzung mit erweiterten relativen Messunsicherheiten kleiner 0,12% zertifiziert. Die ab-solute, kombinierte Standardunsicherheit des prozentualen Stoffmengenanteils der Isotope (Isotopenhäufigkeit) liegt zwischen 0.012 und 0.017.
Dieser Bericht beschreibt die Zertifizierung einer synthetischen Isotopenmischung aus natürlicher und angereicherter Borsäure. Dieses Isotopen-ZRM liegt als konzentrierte, wässerige Borsäure-Lösung vor und ist bezüglich ihrer Isotopenzusammensetzung zertifiziert. Der Bor-Gesamtgehalt ist als Richtwert angegeben. Die Unsicherheiten sind erweiterte Messunsicherheiten mit k=2. Sie sind in Klammern angegeben und beziehen sich auf die letzten beiden Stellen. Das vorliegende Isotopen-ZRM ist bezüglich der Isotopenzusammensetzung mit erweiterten relativen Messunsicherheiten kleiner 0,08% zertifiziert. Die absolute, kombinierte Standardmessunsicherheit des prozentualen Stoffmengenanteils der Isotope (Isotopenhäufigkeit) liegt bei 0,014. In diesem Zertifizierungsbericht wird nur auf die Kapitel eingegangen, die abweichend vom bestehenden Zertifizierungsreport für die Referenzmaterialien BAM I001 bis BAM I003 sind und Einfluss auf die Endergebnisse haben. Dabei handelt es sich um die Kapitel 3.3, 3.4, 4, 6, 7 und 8, Die Kapitel 1, 2, 3, 3.1, 3.2, 5, 9 und 10 des alten Zertifizierungsberichts für die Referenzmaterialien BAM I001 bis BAM I003 behalten unverändert ihre Gültigkeit und sind nicht noch einmal aufgeführt worden.