CYCLOTRON PRODUCTION, RADIOCHEMICAL SEPARATION AND QUALITY-CONTROL OFPLATINUM RADIOTRACERS FOR TOXICOLOGICAL STUDIES

The increasing concentration of Pt, Pd and Rh in the environment is ma inly due to the release of these elements from the catalytic converter s of the motorvehicles. This situation makes it necessary to carry out metallotoxicological experiments on both cell cultures and laboratory animals, in order to assess their impact on living organisms after a Long Term and Low Level Exposure (LLE). Both nuclear reactions Ir-nat( p,xn) and Os-nat(alpha,xn) were investigated in the energy range up to 45 MeV for protons and 38 MeV for alpha-particles, in order to optimi ze the irradiation parameters for the production of Pt-188,Pt-189,Pt-1 91. Several sets of thin- and thick-target excitation functions were d etermined experimentally by cyclotron irradiation at both Milano and I spra cyclotrons. This paper reports the irradiation parameters studied and adopted and two radiochemical procedures for the separation of ra dio-Pt from an Os target, as well as from ruthenium, iridium and gold impurities. These procedures were used to obtain very high specific ac tivity Pt radionuclides in No Carrier Added (NCA) form. Radionuclidic, radiochemical and chemical purity measurements were carried out by th e use of several techniques like gamma-spectrometry, ion-exchange radi o-chromatography, atomic absorption spectrometry and neutron activatio n analysis.