Application of solid phase extractants TEVA and TK200 for the separation of medically relevant 199Au from thermal neutron irradiated Pt target.

This study describes the separation of no-carrier-added (n.c.a.) 199Au from thermal neutron irradiated natural platinum targets using two extraction chromatographic resins: TEVA containing a quaternary amine (Aliquat 336) and TK200 impregnated with trioctylphosphine oxide (TOPO, Cyanex 921). The behavior of Au, Pt, and Ir in HCl media (0.1-10 mol·L-1 HCl) is examined through batch distribution coefficient (Kd) measurements and dynamic column experiments. For TEVA, the Kd of Au remains high across the entire HCl range (2-3·104 mL·g-1), whereas Pt shows a maximum Kd of 3.3·104 mL·g-1 at 1 mol·L-1 HCl, decreasing at higher HCl concentration. Iridium exhibits low Kd values ((10-4.6·102 mL·g-1), consistent with its presence as trivalent species forming weaker complexes with quaternary amines. For TK200, Au Kd ranges from 2·105 to 5·105 mL·g-1, with a slight decrease at high acidity. Pt(IV) reaches a maximum Kd of 2.2·104 mL·g-1 at 1 mol·L-1 HCl. A notable increase in Ir Kd is observed below 1 mol·L-1 HCl, attributed to hydrolysis of iridium chloro complexes. Based on these distribution data, column separation is achieved in acidic media using 1 g of chromatographic resins. Gold is eluted using dilute HCl with thiourea. The separation factors (SFPt/Au) are 1.6·104 for TEVA and 5.9·104 for TK200, while the Pt decontamination factors are 158 and 650, respectively, with overall 199Au yields of 97.6% and 94.1%. The dynamic Pt capacities at 1 mol·L-1 HCl are 0.13 mmol·g-1 for TEVA and 0.22 mmol·g-1 for TK200. The developed separation schemes provide efficient methods for producing medically relevant n.c.a. 199Au from irradiated platinum targets.