Developing ether and alcohol based extraction chromatography resins for purification of antimony-119 in nuclear medicine

Antimony-119 (119Sb, t1/2 = 38.19 h) is an Auger electron emitting radionuclide of interest for radiopharmaceutical therapy. It can be directly produced by proton bombardment of tin-119 using low energy cyclotrons. The radiochemical separation methods available for recovering 119Sb from the bulk Sn target material are lacking, particularly with respect to matrix suitability for further applications. Eight new resins were successfully synthesized, evaluating combinations of two different resin support materials with three different chain lengths of ethers (dibutyl, dipentyl, dioctyl) as well as fluorinated alcohol as the impregnated extractant. All resins showed good stability, losing less than 1% of functional groups in HCl and water. Seven out of eight synthesized resins showed excellent capacity, retaining tens to hundreds of milligrams of Sb per gram of resin. Seven out of eight synthesized resins, as well as one of the resin supports showed good separation between Sb and Sn based on the distribution coefficient studies as well as dynamic elution studies. Our tested resins may be applied for the separation of radiotracer amounts of Sb from bulk Sn target material. We propose the dibutyl ether functionalized divinylbenzene copolymer resin support (DBE-300 resin) as the best candidate, based on the following characteristics: (1) quantitative, concentrated elution of Sn offering compatibility with recycling of enriched 119Sn material; (2) near-quantitative (98%), concentrated recovery of 119Sb in ethanol, providing a matrix resistant to hydrolysis, easy to convert by evaporation, as well as toxicologically insignificant pre-clinically and even clinically.