Orthodox uncertainty budgeting for high accuracy measurements by isotope dilution inductively coupled plasma-mass spectrometry

Briche, Céline S. J. Wolff; Harrington, Christopher F.; Catterick, Tim; Fairman, Ben

doi:10.1016/s0003-2670(01)00894-7

Cited by 26 publications

(15 citation statements)

References 13 publications

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“…The major sources of uncertainty were from the calculated amount content of the primary standard (C z ), the measured isotope ratios of the two blend solutions (R b , and R b 0) and the measured isotope ratios of the sample and the primary standard (R x and R z ), as was also illustrated by Wolffe et al 15 Data evaluation of the literature survey For the statistical evaluation of the compiled data published in the period from 1978 to 2005 the non-parametric estimator, the median was used (Tables 5 and 6). The median absolute deviation (MAD) was used as the non-parametric estimator of the standard deviation.…”

Section: Measurement Uncertaintymentioning

confidence: 87%

A case study for the provision of measurement traceability and measurement uncertainty for the South African reference materials

Botha¹,

Barzev²,

Linsky³

et al. 2005

J. Anal. At. Spectrom.

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The South African Reference Materials (SARMs) have traditionally been certified through interlaboratory studies involving reputable national and international laboratories. The ISO definition of a Certified Reference Material (CRM) has changed recently. In view of these changes re-certification of the SARMs with the use of primary methods to provide measurement traceability and complete evaluation of the uncertainties associated with the methods are urgently needed. The CSIR-National Metrology Laboratory of South Africa (CSIR-NML) has embarked on a project to re-certify some of the rock type South African Reference Materials (SARM 3 and 4) for selected trace elements using the primary method of isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-MS). Analysis data published in the literature for these SARMs since their production and certification in 1978 was also collected and critically evaluated (data due to be published). Based on this work, new recommended values with associated expanded uncertainties are proposed for some trace elements of SARM 3 and SARM 4.

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Section: Measurement Uncertaintymentioning

confidence: 87%

A case study for the provision of measurement traceability and measurement uncertainty for the South African reference materials

Botha¹,

Barzev²,

Linsky³

et al. 2005

J. Anal. At. Spectrom.

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show abstract

“…32 S/ 34 S) detailed elsewhere. 9 Eqn. ( 2) is the full IDMS equation which contains expressions for the natural isotope abundances in the sample (R X ) and calibration standard (R Z ) as well as the sum of all natural isotope ratios in the standard and samples relative to the spike isotope (in this case 34 S).…”

Section: Idms Calculations and Uncertainty Budgetmentioning

confidence: 99%

“…[5][6][7][8] For routine, single collector ICP-MS instruments the uncertainty budget for IDMS is governed primarily by the ability to measure precise isotope ratios with additional contributions from the sample preparation, the primary standard concentration and other minor components. 9 The latest multi-collector ICP-MS instruments enable isotope ratio measurements with extremely high precision (typically 0.05% or better), 10 opening the way for analysis of complex matrix samples by IDMS with uncertainties achievable by few other techniques.…”

Section: Introductionmentioning

confidence: 99%

Development of a high ratio isotope dilution mass spectrometry calibration technique for chemical metrology

Hearn

Evans

Sargent

2005

J. Anal. At. Spectrom.

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IDMS with calibration by ''exact'' or ''approximate signal matching'' methods offers a number of advantages for chemical metrology applications where measurements of low uncertainty are required for analytes at low concentrations in complex matrices. These methods have been applied extensively but are unsuitable for some important applications because in many cases, the concentration of the spike isotope in each measured blend of a sample or standard should be as close as possible to the concentration of the natural analyte isotope. In this paper we discuss recent work investigating the extent to which it is possible to move away from this ideal 1 : 1 blend isotope ratio whilst retaining the key benefits of the approximate matching technique. This has been used for the first time for applications where the sample has a very high analyte concentration, which would require unacceptably high amounts of spike with the existing method. The methodology has been validated for sulfur using a well-characterised candidate matrix reference material -NIST SRM1624d. This is a diesel fuel sample that contains approximately 4000 mg g À1 sulfur. Results were obtained using a ratio for 32 S/ 34 S of 14, achieving accuracy and uncertainty comparable with the original method using a blend isotope ratio of 1.

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“…Eq. 6) by applying the uncertainty propagation law to the expression of the mean [12]: (6) The standard deviation of the mean (standard deviation divided by ) for the three determined blends was used as an estimate of the "between-blend" uncertainty component u between =3.5×10 -13 mol g -1 ( Table 4).…”

Section: Replicate Analysis Of the Wine Samplesmentioning

confidence: 99%

“…The "within" and "between" blend uncertainties were combined using the square root of the sum of the squared uncertainties (coverage factor k = 2) [12]:…”

Section: Replicate Analysis Of the Wine Samplesmentioning

confidence: 99%

Evaluation of the combined measurement uncertainty in isotope dilution by MC-ICP-MS

Fortunato

Wunderli

2003

Analytical and Bioanalytical Chemistry

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The combination of metrological weighing, the measurement of isotope amount ratios by a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS) and the use of high-purity reference materials are the cornerstones to achieve improved results for the amount content of lead in wine by the reversed isotope dilution technique. Isotope dilution mass spectrometry (IDMS) and reversed IDMS have the potential to be a so-called primary method, with which close comparability and well-stated combined measurement uncertainties can be obtained. This work describes the detailed uncertainty budget determination using the ISO-GUM approach. The traces of lead in wine were separated from the matrix by ion exchange chromatography after HNO(3)/H(2)O(2) microwave digestion. The thallium isotope amount ratio ( n((205)Tl)/ n((203)Tl)) was used to correct for mass discrimination using an exponential model approach. The corrected lead isotope amount ratio n((206)Pb)/ n((208)Pb) for the isotopic standard SRM 981 measured in our laboratory was compared with ratio values considered to be the least uncertain. The result has been compared in a so-called pilot study "lead in wine" organised by the CCQM (Comité Consultatif pour la Quantité de Matière, BIPM, Paris; the highest measurement authority for analytical chemical measurements). The result for the lead amount content k(Pb) and the corresponding expanded uncertainty U given by our laboratory was:k(Pb)=1.329 x 10-10mol g-1 (amount content of lead in wine)U[k(Pb)]=1.0 x 10-12mol g-1 (expanded uncertainty U=kxuc, k=2)The uncertainty of the main influence parameter of the combined measurement uncertainty was determined to be the isotope amount ratio R(206,B) of the blend between the enriched spike and the sample.

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Orthodox uncertainty budgeting for high accuracy measurements by isotope dilution inductively coupled plasma-mass spectrometry

Cited by 26 publications

References 13 publications

A case study for the provision of measurement traceability and measurement uncertainty for the South African reference materials

A case study for the provision of measurement traceability and measurement uncertainty for the South African reference materials

Development of a high ratio isotope dilution mass spectrometry calibration technique for chemical metrology

Evaluation of the combined measurement uncertainty in isotope dilution by MC-ICP-MS

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