MULTIELEMENT DETERMINATION IN SEDIMENTS FROM THE GERMAN WADDEN SEA - INVESTIGATIONS ON SAMPLE PREPARATION TECHNIQUES

Multielement determination in sediments from the German Wadden Sea has been carried out using total reflection X-ray fluorescence (TXRF), atomic absorption spectrometry (AAS) and instrumental neutron activation analysis (INAA). Total reflection X-ray fluorescence, in particular, facilitates multielement determination by an easy quantification with internal one-element-standardization and is therefore central to these investigations. In connection with the simplicity of sample preparation using microwave digestion with conc. HNO3, an attractive analytical procedure for routine analyses has been worked out. It allows a quick and accurate multielement determination of the < 20-mu-m-fraction of the Wadden Sea sediments. The sample preparation techniques were optimized by systematic investigations on different digestion methods, i.e. pressure and microwave digestion. The blanks contained negligible amounts in comparison with the element concentrations in the Wadden Sea sediments. The precision of the element analyses varied from 5 to 15%. An accuracy of 5-20% has been obtained by intercomparison of TXRF and INAA as well as by analysing the NBS reference material 1646 (Estuarine Sediment). As an example of routine multielement determination, results of element analyses of sediment samples from the Jadebusen are presented. The element concentrations in the < 20-mu-m-fraction ranged from mg/g for Al, K, Ca and Fe over-mu-g/g for most of the elements (Ti, V, Cr, Mn, Ni, Cu, Zn, Ga, As, Rb, Sr, Y and Pb) to ng/g for Cd and Hg, which is a difference of five orders of magnitude.