DISSOLVED STATES OF TRACE-METAL IONS IN NATURAL-WATER AS ELUCIDATED BY ULTRAFILTRATION SIZE-EXCLUSION CHROMATOGRAPHY ICP-MS

The dissolved states of trace metal ions in natural water have been in vestigated by using the ultrafiltration technique and the combined sys tem of size exclusion chromatography /ICP-MS. The Lake Biwa was chosen as the experimented field. The lake water samples were first filtered with the membrane filter (pore size 0.45 mu m), and then the filtrate solutions were concentrated by 500-fold with the ultrafiltration filt er, which concentrated the large organic molecules with the molecular weight larger than 10,000. The concentrated solutions thus prepared by ultrafiltration were analysed by size exclusion chromatography with t he molecular weight permeation range from 10,000 to 300,000, where the chromatograms were detected by the UV absorption detector and ICP-MS. The analytical methods were applied to the vertical profile measureme nts of the SEC chromatograms in Lake Biwa. In consequence, it has been elucidated that most of metal ions in natural water are in the large organic molecule-metal complex forms.