Two new reference materials based on tobacco leaves: certification for over a dozen of toxic and essential elements.

The preparation, certification, and characterization of two new biological certified reference materials for inorganic trace analysis have been presented. They are based on two different varieties of tobacco leaves, namely, Oriental Basma Tobacco Leaves (INCT-OBTL-5), grown in Greece, and Polish Virginia Tobacco Leaves (INCT-PVTL-6), grown in Poland. Certification of the materials was based on the statistical evaluation of results obtained in a worldwide interlaboratory comparison, in which 87 laboratories from 18 countries participated, providing 2568 laboratory averages on nearly 80 elements. It was possible to establish the certified values of concentration for many elements in the new materials, that is, 37 in INCT-OBTL-5 and 36 in INCT-PVTL-6, including several toxic ones like As, Cd, Hg, Pb, and so forth. The share and the role of instrumental analytical techniques used in the process of certification of the new CRMs are discussed.

Comparison of performance of INAA, RNAA and ion chromatography for the determination of individual lanthanides.

Lanthanides represent an interesting group of elements which are steadily gaining importance in science and in industry. Literature data suggest that they may have a role in regulating cellular processes and also in agriculture enhancing plant growth. Only few instrumental methods like NAA, ICP-OES and ICP-MS have potential for the determination of low levels of all lanthanides, but in practice they often have to be combined with suitable separation/preconcentration methods to achieve maximum number of elements being determined and to assure good accuracy and precision. In this work an attempt has been made to compare the performance of both variants of NAA: purely instrumental activation analysis (INAA) and radiochemical mode (RNAA) with pre- and post-irradiation group separation for the determination of individual lanthanides with the special emphasis on rarely determined elements (Gd, Ho, Er, Tm, Lu). This has been done by the analysis of two reference materials with different matrices viz. biological (CTA-OTL-1) and mineral (CTA-FFA-1). The results are compared with those obtained by ion chromatography (IC) employing the same lanthanide group preseparation scheme as in the case of RNAA.