Pulse radiolytic investigations of iodoplatinates. Application in the determination of platinum in metaphosphate glasses

Abstract

Much work has been carried out on the radiation chemistry of various ions using sodium metaphosphate glass (MP) as a matrix (1).Glass samples are generally prepared by , melting NaH2P04 (mp 620 °C) in platinum crucibles. The crucibles employed were made of pure platinum and supplied by Johnson Matthey Metals Ltd. Using this procedure, we observed the presence of platinum ions in the produced glass samples. A convenient analytical procedure was found to be an adaptation of the iodide spectrophotometric method for platinum (2).The tetraiodoplatinate(II) and hexaiodoplatinate(IV) systems were extensively investigated before (3, 4).The equilibria involved in the present work are:Pt(II) + 4Ptl42" Ki(1) h pti42-+ i3-5=t ptis2-+ r 2(2)t-2 EXPERIMENTAL Spectral Measurements. Ptle2was prepared by equilibration of 10-S-10-4AÍ K2PtCle with 0.05-0.5M HI over a period of 50 hr.We found two peaks, at 492 nm (e = (1.26 ± 0.03) X 104M-1 cm-1 and 343 nm (« = (1.80 ± 0.05) X 104 /-1 cm-1), and a shoulder at 443 nm (e = 0.82 ± 0.02) X 104M-1 cm-1). These results were observed in the presence of 0.5-4M MP (calculated on the basis of