Improved power of determination in SS-ZAAS using pellets of 10 to 20 mg for analysis

Abstract

Solid sampling-Zeeman atomic absorption spectrometry (SS-ZAAS) has been a valuable tool for rapid, direct and reproducible element determination in a broad variety of biological, geological, and environmental materials for more than two decades. However, since the technique was applicable to small amounts of sample mass only (0.02–2.0 mg), until now quantitative analysis by SS-ZAAS has not gained adequate attention. With such a small quantity of sample analyzed, the requirements concerning the sensitivity of the technique or the homogeneity of the material to obtain meaningful results cannot always be fulfilled. Particularly for elements where only a relatively insensitive absorption line is available in relation to the content in low contaminated materials, the technique showed inadequate limits of analysis. In order to overcome these restrictions and to broaden the applicability of the technique, an attempt was made to introduce higher sample masses in the form of pressed pellets (5 to 20 mg) on the graphite boat of the sample introduction system. As an example the analytical parameters and results for thallium analysis in natural biological materials from the German Environmental Specimen Bank (ESB) and in Reference Materials are described. This approach widens the scope of SS-ZAAS as a sensitive, accurate, fast and direct analytical technique for biological and environmental materials and compares well with results obtained by more established techniques such as isotope dilution mass spectrometry with thermal ionization (ID-MS).