Dissolution of metallic platinum as water soluble species by naturally occurring complexing agents

Platinum is released into the environment as a result of surface abrasion from automobile catalysts during operation. Previous investigations showed that this finely dispersed metallic platinum is dissolved in organic matrices, e.g. a humic soil to a significantly high degree, resulting in possibly bioavailable Pt species. In this work several natural complexing agents (adenosine, ADP ATP L-His, humic acid fraction, L-Met, pyrophosphate, and triphosphate) were treated with metallic platinum (as Pt black and as a Pt(0) containing tunnel dust) for 3-60 d. Some of the compounds used dissolved Pt(0) to a recognizable degree, whereas others were in the range of the aqueous blanks. Comparison of Pt black with a natural dust sample showed that L-methionine had in both cases the greatest effect after 60 d. Generally more Pt(0) vias dissolved in the dust sample (finer dispersion and smaller particle size) than in the Pt-black used. By carrying our: the experiment under natural conditions instead of in pure oxygen-, the amounts of dissolved platinum are about one order of magnitude lower.