Thallium speciation in river waters with Chelex-100 resin

A Chelex-100 resin separation technique followed by analysis with atomic absorption spectroscopy was evaluated for the study of thallium speciation in river waters. The detection limit for the method was 1.0 ng/l for both Tl(I) and Tl(III). Analysis of synthetic solutions consistently yielded >90% recovery of these two thallium forms with negligible cross contamination. Water samples from selected stations in polluted Huron River and Raisin River in Michigan were analyzed. Average dissolved thallium concentrations were found to be 21 ng/l for Huron River and 26 ng/l for Raisin River. The dominant thallium form found in these rivers was oxidized Tl(III) and the proportion of Tl(III) to the total dissolved thallium ranged from 43 to 73% and averaged of 66% in water samples analyzed. A significant proportion of Tl(III) may also be in colloidal form. (C) 1999 Elsevier Science B.V. All rights reserved.