COMPARATIVE-STUDY OF DIFFERENT DIGESTION PROCEDURES USING SUPPLEMENTARY ANALYTICAL METHODS FOR MULTIELEMENT-SCREENING OF MORE THAN 50 ELEMENTS IN SEDIMENTS OF THE RIVER ELBE

The suitability of four different digestion procedures, i.e. i.) an aqua regia digestion according to DIN 38 414-S7, ii.) a pressure digestion using HNO3/HF in PTFE-vessels, iii.) a HNO3/HF + HCl-pressure digestion in PTFE-vessels and iv.) a HNO3/HF + HCl-pressure digestion using microwave induction, has been evaluated with regard to the quantitative determination of about 50 elements in environmental samples. Three sediments of the river Elbe and two standard reference materials (MESS-1 and NIST 1645) have been employed. The analytical results from the dissolved samples, obtained using inductively coupled plasma mass- and optical emission spectrometry as well as total reflection X-ray fluorescence spectrometry, have been compared with those obtained by instrumental neutron activation analysis. Only digestion procedures using HNO3/HF with a subsequent evaporation to dryness and dissolution in HCl have led to appropriate results for a wide range of elements (more than 50 elements in total). Because of its low contamination risk and its time saving, the microwave digestion is preferred. For this digestion procedure the accordance among the different instrumental methods used is high (better than 15% deviation) in general. A few elements (16) could be determined quantitatively only by a single method.