| Research Abstract |
Ultra-clean analytical techniques were improved to accurately determine trace amounts of heavy metals in materials. In this study thermal ionization isotope dilution mass spectrometry (IDMS) was employed to analyze concentrations at ppb and ppt levels of Tl, Ag, Cu, Cd, Ni, Pb, Zn and Fe. Blanks for the first seven elements were determined on purest water, acid reagents, ammoniacal water and dithizone-chloroform solution, respectively. The results obtained were very similar to those given by Murozumi et al. (1986)and Nakamura et al. (1988). A preconditioning technique was applied to each step of the dithizone-chloroform extraction method for the eight metals in a given sample solution and to the subsequent evaporation step of the extractant. This particular technique is believed to largely improve on the reproducibility of blanks of the elements under the investigation, although it is not so effective toreduce blanks.
The IDMS for iron could be successfully established. This new analytical method is entirely useful for the accurate determination of trace quantities of Fe as low as 0.2ng, when being combined with ultra-clean analytical techniques. However, the lower limit of Fe quantitative analysis was due to the extent of contamination through the analytical procedure and from the environment of laboratory.
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