Role of Sample Decomposition and Preconcentration in Elemental Trace Analysis

Progress in elemental trace analysis means that lower con— centrations can be determined in a more reliable and efficient way. The demands posed to trace element analysis follow generally the tendency that lower and lower concentrations should be determined in matrices which become more and more complex. The most economical scientific strategy depends strongly on the element to be determined, on the kind of sample and especially, on the power of detection. Therefore, we must develop the strategy of determination in view of two widely differing thoughts: 1. It is necessary to apply direct instrumental methods for routine analysis in order to save time and man—power. This can be done only, if the required power of detection is asserted in view of a suff icient reliability of the results. 2. Multi-stage combined procedures have to be preferred in all cases, where direct instrumental methods still yield insufficient or incorrect results, in spite of the fact that they are usually more time and/or labour consuming. This paper intends to concentrate in particular on these procedures, in which decomposition and preconcentration methods have to precede the actual end—determination. The main goal is the minimization of systematic errors which become more crucial at the low concentrations involved. Especially those combined methods of a high degree of universality and reliability will be considered. Examples will be given for the determination of Hg, Se, Tl and B at ng/g and pg/g levels.