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 investigated by using the ultrafiltration technique and the combined system 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 filter, 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 the 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 measurements 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.