OPTIMIZED MICROWAVE PREPARATION PROCEDURE FOR THE ELEMENTAL ANALYSIS OF AQUATIC SEDIMENT

This paper summarizes several key points in applying the microwave pre paration technique to the elemental analysis of aquatic sediments and reports systematic experiments in searching for an optimal microwave p reparation procedure for element analysis in sediment samples. The det ermination of the elements Cu, Pb and Cd in a standard reference aquat ic sediment sample (CRM 280, COMEUR) was achieved by first digesting t he samples in a microwave oven equipped with PFA advanced composite ve ssels, followed by AAS measurement. The influence of microwave power, digestion time, various dissolution reagents and the HF removing condi tions was studied. It has been shown that for a 0.1 g sediment sample the optimal microwave preparation conditions are: 4-5ml HNO3/HF/H2O2 a s solvent, digesting time 30 min with 100% microwave power and evapora ting the residual acid within 8 min in an open vessel at 80 degrees C. The element recovery rates with AAS measurement can reach up to 92.4- 100.6%.