ONLINE COUPLING OF ION CHROMATOGRAPHY AND ATOMIC SPECTROMETRY AND USEOF DIRECT GRAPHITE-FURNACE ATOMIC-ABSORPTION SPECTROMETRY AS NEW TOOLS FOR ULTRA-TRACE DETERMINATIONS IN REFRACTORY-METALS

On-line coupling of inductively coupled plasma (ICP) techniques such a s ICP-AES and ICP-MS with ion chromatography (IC) offers unique featur es for ultra-trace analysis. An on-line preconcentration procedure bas ed on cation exchange enables sub-ng/g analysis in complex matrices li ke molybdenum and tungsten. The best dissolution reagent for these mat rices is hydrogen peroxide, which can be cleaned to ultra high purity with the same metal free chromatography equipment used for the preconc entration. Preconcentration is possible for elements that show cationi c reactions within acidic peroxide containing solutions. In this study 28 elements detrimental for microelectronics applications are observe d. A comparison of the combinations IC-ICP-AES and IC-ICP-MS with glow discharge mass spectrometry (GDMS) for the analysis of today's purest tungsten samples shows the analytical power and accuracy of the coupl ed devices. Graphite furnace atomic absorption spectrometry (GFAAS) as an extremely sensitive analytical technique is applied with and witho ut the same sample pretreatment as used for the on-line coupling. Dire ct GFAAS measurements of alkali metals are complementary to IC-ICP tec hniques. The data evaluated with these wet chemical techniques are com pared to the usual manufacturers characterisation technique GDMS. With respect to the low concentrations present in these high purity materi als (ng/g level in the solid) the discrepancies between all methods ar e acceptable. The sensitivity of IC-ICP-MS is in most cases far superi or to IC-ICP-AES and for some elements also to GDMS. Furthermore the s pecific advantages of on-line coupling such as the elimination of isob aric interferences in ICP-MS or spectral interferences in ICP-AES are shown for ICP-AES and ICP-MS determinations.