By means of instrumental neutron activation, more than 20 trace elements are determined in suspended matter in Rhine water,
Main water and Rhine sediments. Monoelement and multielement standards are used for calibration. Sample collection, separation
of suspended matter by filtration or centrifugating and sample preparation are described. The results obtained by filtration
and by centrifuging are compared. Interferences in evaluation of the γ-spectra and their influence on the results are discussed.
Systematic errors are detected by participation in ring analysis.