Standard Reference Materials NIST

The set of Glass Standard Reference Material NIST SRM 610 - 614 was used for quantification of amount up to 45 trace elements in the synthetic oxide single crystals and natural quartzites. 

Figure 6.12 RSCs of two standard reference materials (NIST SRM 612 glass standard and BRC 2G basaltic glass prepared from BCR-2 reference material) measured by LA-ICP-MS.30 (j. S. Becker et ai, Mikrochim. Acta 135, 71 (2000). Reproduced by permission of Springer Science and Business Media.)...

An analytical procedure has been proposed for precise uranium isotope ratio measurements in a thin uranium layer on a biological surface by LA-ICP-MS using a cooled laser ablation chamber.125 One drop of uranium isotope standard reference materials NIST, 350, NIST 930, of our isotopic laboratory standard CCLU 500 (20p.l, U concentration 200 ng 1) and of uranium with natural isotopic pattern were deposited on the leaf surface and analyzed by LA-ICP-MS at well defined laser crater diameters of 10, 15, 25 and 50 p.m. A precision for measurements of isotope ratios in the range of 2.1-1.0% for 235U/238U in selected isotope standards was observed whereby the precision and the accuracy of isotope ratios compared to the non-cooled laser ablation chamber was improved.125... 

MS. After careful homogenization, the dried urine samples were analyzed directly by LA-ICP-MS without any time consuming digestion procedure. Matrix matched synthetic laboratory standards doped with Th (IRMM 60), uranium with natural isotope composition ( U/ U = 0.00725) and uranium isotope standard reference material (NIST U-930) at the low pgml level were prepared in order to smdy the figures of merit of the analytical methods developed. The recovery rate for thorium and uranium concentration measured on a synthetic urine laboratory standard by LA-ICP-MS varied between 91 and 104%. The precision and accuracy of the analytical methods was found to be 7 % and < 1 %, respectively, for uranium concentration, by using urine laboratory standards (at uranium concentration O.lngml. ... 

Fifteen to 18 elements are determined by Markert (1996) in plant standard reference materials (NIST-SRM 1572,1575 and BCR-SRM-281). In NIST-SRM-1572 the accuracy for some of the elements (As, Pb, Mo) is not satisfactory. In the analysis of NIST-SRM-1643a (Markert et al., 1997) determine 12 elements with excellent analytical characteristics in the p,g/g and ng/g regions. Forty-five elements are determined by Madeddu and Rivoldini (1996) in plants and standard reference materials reaching 0.2 ng/g detection limits, and McLaren et al. (1995) use ICP-MS for certification of plant reference materials in the sub-nanogram range for 16 elements. 

The position of ICP-AES among other instrumental techniques for trace analysis is well established. Although instrumentation is still developing it is more in respect to reduce laborious introductions of dilferent types of corrections than increase the quality of analysis. As an interesting example in this respect a comparison of ICP-AES analysis of soil and sediment standard reference materials done in 1985 (Liese, 1985a) and 1998 (Leivuori, 1998) may be done. In 1985 the content of 21 elements in IAEA soil, five and 19 elements in IAEA SL-1 has been determined after introduction of two type of corrections. The accuracy was 0.1-18% and precision below 10%. In 1998 in a sediment standard reference material (NIST-SRM-2704 - Buffalo River Sediment) ten elements were determined (for the rest of the elements in this study ETAAS is preferred) with accuracy of 0.1-16% and precision below 10%. The same result is obtained if a comparison of analysis of plant standard reference materials is done (Liese, 1985a Kos et al., 1996 Djingova et al., 1998). 

A reasonable goal of this is to reach an average accuracy of quantification in the range of ca 5% for elements above atomic number 12 determined through their K and L fluorescence radiation. O Table 34.1 shows a few results obtained for the standard reference material NIST SRM 1577b bovine liver (see also the related Figs. 34.2 and 34.4). 

To quantify images of parts of heavy-metal-tolerant plants (leaves of Elsholtzia splendens) in order to study the hyperaccum-mulation of Cu and Zn, the standard reference material, NIST SRM 1515 apple leaves, was doped, mixed and homogenized with analytes of defined concentration. The quantification was performed via an external calibration procedure by measuring the calibration curves. Another standard reference material, NIST SRM 1547 Peach Leaves, was used to validate the analytical procedure (44, 45). 

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