title: Separation of cyclotron-produced44Sc from a natural calcium target using a dipentyl pentylphosphonate functionalized extraction resin.
abstract: Significant interest in44Sc as a radioactive synthon to label small molecules for positron emission tomography (PET) imaging has been recently observed. Despite the efforts of several research groups, the ideal44Sc production and separation method remains elusive. Herein, we propose a novel separation method to obtain44Sc from the proton irradiation of calcium targets based on extraction chromatography, which promises to greatly simplify current production methodologies. Using the commercially available Uranium and Tetravalent Actinides (UTEVA) extraction resin we were able to rapidly (<20min) recover >80% of the activity generated at end of bombardment (EoB) in small ~1M HCl fractions (400μL). The chemical purity of the44Sc eluates was evaluated through chelation with DOTA and DTPA, and by trace metal analysis using microwave induced plasma atomic emission spectrometry. The distribution coefficients (Kd) of Sc(III) and Ca(II) in UTEVA were determined in HCl medium in a range of concentrations from zero to 12.1M. The44Sc obtained with our method proved to be suitable for the direct labeling of small biomolecules for PET imaging, with excellent specific activities and radiochemical purity.
authors.affiliation: Medical Physics Department, University of Wisconsin-Madison, Madison, WI, USA. Electronic address: hvaldovinos@wisc.edu.
authors.forename: H F
authors.initials: HF
authors.lastname: Valdovinos
authors.affiliation: Medical Physics Department, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: R
authors.initials: R
authors.lastname: Hernandez
authors.affiliation: Medical Physics Department, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: T E
authors.initials: TE
authors.lastname: Barnhart
authors.affiliation: Medical Physics Department, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: S
authors.initials: S
authors.lastname: Graves
authors.affiliation: Medical Physics Department, University of Wisconsin-Madison, Madison, WI, USA; Department of Radiology, University of Wisconsin-Madison, WI, USA; University of Wisconsin Carbone Cancer Center, Madison, WI, USA.
authors.forename: W
authors.initials: W
authors.lastname: Cai
authors.affiliation: Medical Physics Department, University of Wisconsin-Madison, Madison, WI, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Nickles
keywords: (44)Sc; PET; Radiochemical separation; Radioisotope production; Radiolabeling; Radiometal; Scandium-44