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  • 1
    Electronic Resource
    Electronic Resource
    Stable isotope analysis of iron by gas-phase electron impact mass spectrometry (1993)
    s.l. : American Chemical Society
    Analytical chemistry 65 (1993), S. 3166-3167 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00069a036
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  • 2
    Electronic Resource
    Electronic Resource
    Producing SI-traceable reference values for Cd, Cr and Pb amount contents in polyethylene samples from the Polymer Elemental Reference Material (PERM) project using isotope dilution mass spectrometry (2000)
    Springer
    Accreditation and quality assurance 5 (2000), S. 314-324 
    Details
    ISSN: 1432-0517
    Keywords: Key words PERM ; ICP-MS ; PTI-MS ; IDMS ; Uncertainty budget ; Certification ; Polyethylene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The present paper describes the certification of the amount content of Cd, Cr and Pb in two different polyethylene materials within the third phase of the Polyethylene Elemental Reference Material (PERM) project. The analytical procedure to establish the reference values for Cd, Cr and Pb amount contents in these materials is based on isotope dilution mass spectrometry used as a primary method of measurement. Cd and Pb were measured with inductively coupled plasma-mass spectrometry and Cr with positive thermal ionization-mass spectrometry. The decomposition of the polymer matrix was carried out using a high pressure asher. Reference values for amount content, traceable to the SI-system, have been obtained for these three elements in both of the polyethylene samples of PERM. For each of the certified amount content values an uncertainty budget was calculated using the method of propagation of uncertainties according to ISO and EURACHEM guidelines. The measurement procedures, as well as the uncertainty calculations, are described for all three elements. In order to keep the whole certification process as transparent as possible, the preparations of various reagents and materials as well as the sample treatment and blending are described in detail. The mass spectrometry measurements and the data treatment are also explained carefully. The various sources of uncertainty present in the procedure are displayed in the uncertainty budgets. The obtained combined uncertainties for the amount content values were less than 2% relative (k=1) for all investigated elements. The amount contents were in the μmol/kg range, corresponding to mg/kg levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007690000146
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  • 3
    Electronic Resource
    Electronic Resource
    Establishment of SI-traceable reference ranges for the content of various elements in the IMEP-9 water sample (2000)
    Springer
    Accreditation and quality assurance 5 (2000), S. 331-338 
    Details
    ISSN: 1432-0517
    Keywords: Key words IMEP ; Certification ; Uncertainty calculation ; Metals in water ; Interlaboratory comparison
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The International Measurement Evaluation Programme (IMEP) attempts to shed light on the current state of the practice in chemical measurements. The main tool, which assists this attempt and also differentiates IMEP from similar projects, is the establishment of SI-traceable reference ranges (where possible) for the elements offered for measurement to the participants for every IMEP round. The Institute for Reference Materials and Measurements (IRMM), as the founder and co-ordinator of IMEP has the responsibility of establishing the SI-traceable reference ranges. This is a large task that requires knowledge, skill and resources. IRMM collaborates with a network of reference laboratories in order to achieve the establishment of SI-traceable reference ranges in a transparent and reliable way. The IMEP reference laboratories must have demonstrated experience and have a proven and successful record in the use of primary methods of measurements (mainly isotope dilution mass spectrometry) and the application of uncertainty evaluation according to ISO/BIPM guidelines. In IMEP-9 "trace elements in water", results from 7 reference laboratories (including IRMM) were combined by IRMM to establish SI-traceable ranges for the 15 elements, which were then offered for measurement to the 200 participants worldwide. This paper does not discuss the individual contribution of the reference laboratories (this could be the subject of individual papers) but describes the procedures and criteria used in order to establish the reference ranges for the IMEP-9 samples by combining the individual contributions. All results submitted to IRMM are included, so as to make this publication as realistic as possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00010424
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  • 4
    Electronic Resource
    Electronic Resource
    The IRMM International Measurement Evaluation Programme (IMEP) IMEP-7: Inorganic components in human serum (1999)
    Springer
    Accreditation and quality assurance 4 (1999), S. 463-472 
    Details
    ISSN: 1432-0517
    Keywords: Key words Comparability ; Traceability ; Isotope-specific methods ; Isotope dilution mass spectrometry ; Neutron-activation analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  In the seventh round of the Institute for Reference Materials and Measurements' International Measurement Evaluation Programme, 277 clinical laboratories from 17 countries participated. The measurands consisted of inorganic components, present at minor and trace level, in a human liquid serum. Results for calcium, chloride, copper, magnesium, sodium, selenium and zinc are reported and are compared to reference values established mainly by isotope dilution mass spectrometry and neutron-activation analysis. The overall conclusion is that routine measurements of total concentrations of the components by clinical laboratories are of high quality. The fraction of significant errors is small (0.5%) and the self-declared uncertainty values are generally fairly realistic. Results are further commented on with respect to the recent development in metrology in chemistry.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007690050413
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  • 5
    Electronic Resource
    Electronic Resource
    Contribution to the certification of B, Cd, Mg, Pb, Rb, Sr, and U in a natural water sample for the International Measurement Evaluation Programme Round 9 (IMEP-9) using ID-ICP-MS (2000)
    Springer
    Accreditation and quality assurance 5 (2000), S. 272-279 
    Details
    ISSN: 1432-0517
    Keywords: Key words IMEP-9 ; ID-ICP-MS ; IDMS ; Uncertainty budget ; Certification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The present paper describes the contribution of the Institute for Reference Materials and Measurements to the certification of B, Cd, Mg, Pb, Rb, Sr, and U amount contents in a natural water sample, in round 9 of the International Measurement Evaluation Programme (IMEP-9). The analytical procedure to establish the reference values for B, Cd, Mg, Pb, Rb, Sr, and U amount contents was based on isotope dilution inductively coupled plasma-mass spectrometry used as a primary method of measurement. Applying this procedure reference values, traceable to the SI, were obtained for the natural water sample of IMEP-9. For each of the certified amount contents presented here a total uncertainty budget was calculated using the method of propagation of uncertainties according to ISO and EURACHEM guidelines. The measurement procedures, as well as the uncertainty calculations are described for all seven elements mentioned above. In order to keep the whole certification process transparent and so traceable, the preparations of various reagents and materials as well as the sample treatment and blending, the measurements themselves, and finally the data treatment are described in detail. Explanations focus on Pb as a representative example. The total uncertainties (relative) obtained were less than 2% for all investigated elements at amount contents in the pmol/kg up to the high μmol/kg range, corresponding to low μg/kg and mg/kg levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007690000145
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  • 6
    Electronic Resource
    Electronic Resource
    Measuring metal homogeneity in a matrix via the measurement of the ratio metal to matrix oxide using ICP-MS (1999)
    Springer
    Fresenius' journal of analytical chemistry 364 (1999), S. 437-439 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple method has been developed that allows a fast determination of the homogeneity of an element M in an alloy, even for minor components. This is done by measuring a ratio of ion currents I, I M/I M’O, whereby M’ is the matrix element, by inductively coupled plasma mass spectrometry (ICP-MS). The method can be used to determine the homogeneity of one component in a binary alloy and allows to estimate the sample size necessary to minimise uncertainty contributions due to inhomogeneity in the analysis of such an alloy. In this work the homogeneity of a niobium/0.1% zirconium alloy was determined on 1 mg samples. Accurate weighings of these small samples are not required, as the method is based on the measurement of the niobium/zirconium amount ratio in the dissolved samples. As this ratio is fairly large, the Zr/NbO amount ratio was measured instead to decrease the magnitude of the measured ratio. This ratio was found to be sufficiently stable over time for homogeneity testing. In this particular case the Zr/NbO ratio in the samples was found to vary by 0.049 relative for a 1 mg samples size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051364
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  • 7
    Electronic Resource
    Electronic Resource
    Preparation and characterisation of synthetic mixtures of lithium isotopes (1998)
    Springer
    Fresenius' journal of analytical chemistry 361 (1998), S. 767-773 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Re-certification of the absolute isotopic composition of the natural lithium isotopic reference material (IRM), IRMM-016, requires measurements calibrated by means of synthetic mixtures of highly enriched lithium isotopes. Ten such mixtures were prepared by weighing and mixing of two well characterised, isotopically enriched, Li2CO3 compounds. The starting materials, 99.9981% enriched 6Li, and 99.9937% enriched 7Li, were purified by ion exchange, and the purified materials converted from LiOH to Li2CO3 by reaction with CO2. Ten new mixtures were prepared by mixing different weighed amounts of these dissolved Li2CO3 carrier compounds. The compounds had an estimated level of impurities of 100 ± 100 μg · g–1 (expanded uncertainty with a coverage factor of 2). In the ten mixtures, the n(6Li)/n(7Li) ratio varies from 0.025 to 14 and the achieved expanded relative uncertainty on the amount ratio prepared is typically 2 · 10–4. These mixtures were then used to determine the correction factor, K, for mass discrimination of the measurement procedure and instrument concerned.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051013
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  • 8
    Electronic Resource
    Electronic Resource
    SI-traceable values for cadmium concentration in the water samples of IMEP-6 (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 1020-1023 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The certification measurement for the cadmium concentration in the samples as performed by Isotope Dilution (ID) using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is described in framework of the International Measurement Evaluation Programme (IMEP). By using a primary method of measurement (ID), making up a full uncertainty budget and using a sensitive technique (ICP-MS), reference values traceable to SI can be obtained for this material. The uncertainty budget is performed in accordance with the ISO and EURACHEM guides on uncertainty. A comparison is made with certification results of other experienced laboratories also using primary methods where possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050297
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  • 9
    Electronic Resource
    Electronic Resource
    The importance of the Avogadro constant for amount-of-substance measurements (1998)
    Springer
    Fresenius' journal of analytical chemistry 361 (1998), S. 227-234 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract One of the routes to re-determine the Avogadro constant requires ultra-high accuracy isotopic measurements of amount ratios of Si isotopes to 10–5 reproducibilities on the ratio measurements and calibrating the results by synthetic isotope mixtures prepared to 2 · 10–5 relative combined uncertainty. The route to these results is described, followed by a description of the improvement of our knowledge of the Avogadro constant N A through these measurements. The same route has recently been opened for other gases and has opened the way to the establishment of “Primary Standards of Measurements” for gas isotopic measurements. It is described how these highly accurate measurements of ratios of amount of substance have considerably contributed to clearer thinking about concepts for measurements of amount of substance. The acquired expertise in measurement instrumentation and measurement procedures can now be extended to a more general use in measurements of isotope amount ratio (i.e. in other elements). It can also be combined with isotope dilution. This latter combination opens up a new route towards a realization of traceability of an amount-of-substance measurement to the SI and to the (measurement procedure and instrumentation leading to) Avogadro constant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050870
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  • 10
    Electronic Resource
    Electronic Resource
    Comparative performance study of ICP mass spectrometers by means of U “isotopic measurements” (2000)
    Springer
    Fresenius' journal of analytical chemistry 368 (2000), S. 148-155 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The performance of four commercially available ICPMS instruments of three different types was compared by means of uranium “isotopic measurements”. Examined were two quadrupole sector (different generation, different manufacturer), one single detector double focusing magnetic sector and one multiple collector double focusing magnetic sector instruments. The same samples of the IRMM-072 series were used under routine conditions to measure the 233U/235U and the 233U/238U ratios which, in these samples, vary over almost three orders of magnitude from ∼ 1 to ∼ 2 · 10–3. Within expanded (k = 2) uncertainties, good agreement was observed between the certified values and the data internally corrected for mass-discrimination effects. The magnitude of the evaluated uncertainties was different for each type of instrument. With the multiple collector instrument, expanded uncertainties varied from ± 0.04% to± 0.24% for the 233U/235U ratio, and from ± 0.08% to ± 0.27% for the 233U/238U ratio. They were ∼ 1 to 5 times larger with the single detector magnetic sector instrument, and ∼ 10 to 25 times larger with both quadrupole sector instruments. With the multiple collector instrument, repeatability of the measurements seemed to be limited by the difficulty of correcting properly for instrumental background, whereas with the single detector magnetic sector instrument the counting statistics was the only limitation (on smallest ratios). Apparent mass-discrimination was clearly found to be larger but more reproducible (and hence easier to correct for) in the case of magnetic sector instruments than for both quadrupole sector instruments. If space charge effects were the main source of mass-discrimination for all instruments, these results are in contradiction with the hypothesis of the size of mass-discrimination decreasing with the acceleration voltage. With the single detector magnetic sector instrument in particular (when operated by changing the ion energy only), our results pointed at more than only one major source of mass-discrimination, with variable size depending on the ratios measured.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160000499
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