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

Botha, Adéle; Barzev, Alexander I.; Linsky, Sophia M.; Fischer, Johann L.

doi:10.1039/b501354b

Cited by 11 publications

(14 citation statements)

References 9 publications

(10 reference statements)

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“…Many of the widely used rock RMs were characterised decades ago using the best practices available at the time of their production. In the determination of trace elements in particular, technical advances now permit more reliable and precise measurements (Dulski 2001, Raczek et al 2001, Makishima et al 2002, Pin et al 2003, Botha et al 2005, Pearce et al 2007. As an outcome, many older RMs lack values for many constituents or they have large uncertainties, limiting their applicability.…”

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confidence: 99%

“…As a consequence, most of the available elemental IDMS values were published after the rock RMs were issued. An example is the work carried out by Botha et al (2005Botha et al ( , 2007 and Botha (2010), for eight trace elements (Ba, Cd, Cu, Mo, Ni, Pb, Sr and Zn) in three South African Reference Materials (SARM) certified by the Council for Mineral Technology (MINTEK), in the 1970s. Vogl (2012) compared the capabilities of single, double and triple IDMS and concluded that the three techniques can produce equally accurate results.…”

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confidence: 99%

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Determination of Cr, Cu, Ni, Sn, Sr and Zn Mass Fractions in Geochemical Reference Materials by Isotope Dilution ICP‐MS

Cotta

Enzweiler

2012

Geostandard Geoanalytic Res

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Isotope dilution (ID) mass spectrometry is a primary method of analysis suited for the accurate and precise measurement of several trace elements in geological matrices. Here we present mass fractions and respective uncertainties for Cr, Cu, Ni, Sn, Sr and Zn in 10 silicate rock reference materials (BCR‐2, BRP‐1, BIR‐1, OU‐6, GSP‐2, GSR‐1, AGV‐1, RGM‐1, RGM‐2 and G‐3) obtained by the double ID technique and measuring the isotope ratios with an inductively coupled plasma‐mass spectrometer equipped with collision cell. Test portions of the samples were dissolved by validated procedures, and no further matrix separation was applied. Addition of spikes was designed to achieve isotope ratios close to unity to minimise error magnification factors, according to the ID theory. Radiogenic ingrowth of 87Sr from the decay of 87Rb was considered in the calculation of Sr mass fractions. The mean values of our results mostly agree with reference values, considering both uncertainties at the 95% confidence level, and also with ID data published for AGV‐1. Considering all results, the means of the combined uncertainties were < 1% for Sr, approximately 2% for Sn and Cu, 4% for Cr and Ni and almost 6% for Zn.

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confidence: 99%

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confidence: 99%

Determination of Cr, Cu, Ni, Sn, Sr and Zn Mass Fractions in Geochemical Reference Materials by Isotope Dilution ICP‐MS

Cotta

Enzweiler

2012

Geostandard Geoanalytic Res

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“…The older RMs from South Africa (Steele et al. 1978) have been recently analysed by Botha et al. (2005, 2007) for a few trace elements using so‐called ‘definitive’ techniques such as isotope dilution‐ICP‐MS (ID‐ICP‐MS).…”

Section: Resultsmentioning

confidence: 99%

“…1995, b Govindaraju 1995, c Steele et al. 1978, d Botha et al. 2005, e Govindaraju 1984); the subscripts lit and tw are literature and this work, respectively; n/a information not available.…”

Section: Resultsmentioning

confidence: 99%

Comparison of Two Sample Preparation Methods for X-Ray Fluorescence Spectrometry in the Determination of Ni and Cr

Verma

González-Ramírez

Rodríguez-Ríos

2011

Geostandards and Geoanalytical Research

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Pressed powder pellets and fused beads or glass disks are routinely used in X‐ray fluorescence spectrometry for the determination of major and trace elements, respectively, in geological materials. In order to evaluate the performance of these two sample preparation methods, we determined Ni and Cr concentrations of fourteen RMs from Japan, France and South Africa, and eighty‐five igneous and three sedimentary rock samples from Mexico in both powder pellets and glass beads. We also computed new values of statistical parameters for RMs from an outlier‐based multiple‐test method and compared them with the literature mean and confidence limit values. The results showed that the multiple‐test method provided more reliable central tendency and dispersion parameters for RMs than those obtained previously from the two or three standard deviation method, or from robust methods. The powder pellet and fused bead sample preparation methods provided consistent results for Ni and Cr at concentration levels > 50 μg g−1 in this application; for lower concentration levels, however, these methods showed somewhat greater differences. For quantitative comparisons, both ordinary and weighted least‐squares linear regression models were used to show that the two sample preparation methods provided generally unbiased results.

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“…Uncertainty in the certified value-Uncertainty in the certified values was calculated in a manner consistent with the ISO Guidelines for the Expression of Uncertainty in Measurement (GUM) 27 . The procedure used was developed from the guidelines provided by NIST, 34 Eurachem 35 , and from examples given by Ellison et al 36 , Botha et al 37 and Sturgeon et al 32 The uncertainty for our analysis of SRM 1486 Bone Meal is also given; it was approximately twice the uncertainty as stated by NIST on the certificate.…”

Section: Sample Drying Proceduresmentioning

confidence: 99%

Characterization of candidate reference materials for bone lead via interlaboratory study and double isotope dilution mass spectrometry

Bellis

Hetter

Verostek

et al. 2008

J. Anal. At. Spectrom.

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Four candidate ground bone reference materials (NYS RMs 05-01 through 04), were produced from lead-dosed bovine and caprine sources, and characterized by interlaboratory study. The consensus value ( X ) and expanded standard uncertainty (U(X) ) were determined from the robust average and standard deviation of the participants' data for each NYS RM 05-01 through 04. The values were 1.08 ±0.04, 15.3 ±0.5, 12.4 ±0.5, and 29.9 ±1.1 μg g(-1) Pb, respectively. Youden plots of z-scores showed a statistically significant correlation between the results for pairs of NYS RM 05-02 through 04, indicating common sources of between-laboratory variation affecting reproducibility. NYS RM 05-01 exhibited more random variability affecting repeatability at low concentration. Some participants using electrothermal atomic absorption spectrometry (ETAAS) exhibited a negative bias compared to the all-method consensus value. Other methods used included inductively coupled plasma mass spectrometry (ICP-MS), isotope dilution (ID-) ICP-MS, and ICP atomic (optical) emission spectroscopy (-OES). The NYS RMs 05-01 through 04 were subsequently re-analyzed in house using double ID-ICP-MS to assign certified reference values (C ) and expanded uncertainty (U(C) ) of 1.09 ± 0.03, 16.1 ± 0.3, 13.2 ± 0.3 and 31.5 ± 0.7, respectively, indicating a low bias in the interlaboratory data. SRM 1486 Bone Meal was analyzed for measurement quality assessment obtaining results in agreement with the certified values within the stated uncertainty. Analysis using a primary reference method based on ID-ICP-MS with full quantification of uncertainty calculated according to ISO guidelines provided traceability to SI units.

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

Cited by 11 publications

References 9 publications

Determination of Cr, Cu, Ni, Sn, Sr and Zn Mass Fractions in Geochemical Reference Materials by Isotope Dilution ICP‐MS

Determination of Cr, Cu, Ni, Sn, Sr and Zn Mass Fractions in Geochemical Reference Materials by Isotope Dilution ICP‐MS

Comparison of Two Sample Preparation Methods for X-Ray Fluorescence Spectrometry in the Determination of Ni and Cr

Characterization of candidate reference materials for bone lead via interlaboratory study and double isotope dilution mass spectrometry

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