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Abstract: Production of 38Cl and 34mCl via the (d, α) reaction on natural argon and 36Ar reveal medical cyclotrons’ ability to supply these isotopes in small quantities. 38Cl provides an inexpensive developmental tool, while 34mCl is a positron emitter of interest in PET imaging. Production yields, cyclotron target development, cryo-recovery of enriched gases, and nucleophilic chemistry of a model compound are described. [Copyright &y& Elsevier]

52gMn is a promising radionuclide for positron emission tomography (PET). Enriched 52Cr targets are required to minimize formation of 54Mn radioisotopic impurities during production with proton beams. The need for radioisotopically pure 52gMn, accessibility and cost of 52Cr, sustainability of the radiochemical process, and potential for iterative purification of target materials motivate this development of recyclable, electroplated 52Cr metal targets and radiochemical isolation and labeling with resulting >99.89% radionuclidically pure 52gMn. The run-to-run replating efficiency is 60 ± 20%, and unplated chromium from this method is recovered with 94% efficiency as 52CrCl 3 hexahydrate. The decay-corrected molar activity of chemically isolated 52gMn for common chelating ligands was 376 MBq/μmol. • Manganese-52g is a promising radionuclide for positron emission tomography. • Enriched 52Cr targets are required to minimize formation of 54Mn radioisotopic impurities during production with proton beams. • Development of recyclable, electroplated 52Cr metal targets. [ABSTRACT FROM AUTHOR]

Cobalt-55 and -58m form a theranostic pair that has relevant properties for cancer research. We report a cation exchange chromatography/extraction chromatography method that separates cyclotron-produced 55/58mCo from 54/57Fe in <1.5 h, recovers >85% Co and achieves [55Co]Co-NOTA and -DOTA AMA 89 ± 48 and 35 ± 7 MBq/nmol (EOB), respectively. Cobalt-55 and -58m were quantitatively labeled to functionalized NOTA at 106 and 50 MBq/nmol (EOB), respectively, corroborating measured AMA. This method is faster than previously published methods and achieves better [55/58mCo]Co-NOTA and -DOTA AMA. • [55Co]Co-NOTA/DOTA apparent molar activity 89 ± 48/35 ± 7 MBq/nmol (N=6) at EOB. • 58mCo quantitatively labeled at 50 MBq/nmol to functionalized NOTA (EOB). • 55/58mCo separated from 54/57Fe via cation exchange and extraction chromatography in < 1.5 h. • >85% Co RCY in 1 mL and >99.99% 55Co radionuclidic purity. • >98% 54/57Fe recovery and resulting 54/57Fe can be electrodeposited. [ABSTRACT FROM AUTHOR]

Abstract We report a novel, precipitation-based method for the isolation of Mn from Cr targets for cyclotron production of 52gMn. The separation produces no-carrier-added 52gMn with a decay corrected radiochemical yield of 85 ± 3% and apparent molar activity for DOTA of 1.3 GBq/μmol. This method reduces stable metallic impurities in the purified 52gMn compared to previously reported chromatographic methods. Highlights • Radiochemical separation using a 2-phase precipitation method and single extraction chromatography column. • Separation strategy for production no-carrier-added 52gMn. • Process allows for chelation studies with DOTA. [ABSTRACT FROM AUTHOR]

Abstract We present a simplified, automatable single-column radiochemical separation method using the extraction chromatographic branched-DGA resin for the production of no-carrier-added 86Y with a radiochemical yield higher than 95%, an apparent molar activity of 1.4 ± 0.4 Ci/μmol (DOTA) and 2.3 ± 0.7 Ci/μmol (DTPA), and a run-to-run recycling efficiency of the isotopically-enriched target of 98 ± 1%. These results enable the preparation of 86Y radiopharmaceuticals for 86Y/90Y-based cancer theranostic applications. Highlights • Simple radiochemical separation using single column extraction chromatography. • Separation strategy for production of high-quality theranostic Y-86 applications. • Process allows for high recycling efficiency of the enriched target material. [ABSTRACT FROM AUTHOR]

This work characterizes the radiochemical synthesis, purification, and formulation of [ 18 F]THK-5351, a tau PET radioligand, and develops an automated radiosynthesis routine (ELIXYS, Sofie Biosciences). Nucleophilic radiofluorination reaction was complete by 7 min at 110 °C with radiochemical yields proportional to precursor mass (0.1–0.5 mg). Optimized HPLC purification produced radiotracer product with no chemical impurities observed on analytical HPLC in formulation. Automated radiosynthesis (ELIXYS), HPLC purification and formulation was completed in 86 min producing formulated product suitable for human research use. [ABSTRACT FROM AUTHOR]

Zirconium-89 finds broad application for use in positron emission tomography. Its cyclotron production has been limited by the heat transfer from yttrium targets at high beam currents. A spot welding technique allows a three-fold increase in beam current, without affecting 89 Zr quality. An yttrium foil, welded to a jet-cooled tantalum support base accommodates a 50 µA proton beam degraded to 14 MeV. The resulting activity yield of 48±4 MBq/(μA∙hr) now extends the outreach of 89 Zr for a broader distribution. [ABSTRACT FROM AUTHOR]

[11C]ER176 is a next generation PET radioligand for imaging 18 kDa translocator protein, a biomarker for neuroinflammation. The goal of this work was to investigate alternative strategies for the radiochemical synthesis, purification, and formulation of [11C]ER176. An optimized tri-solvent high-performance liquid chromatography (HPLC) protocol is described to separate the hydro-de-chlorinated byproduct from [11C]ER176. A newly implemented solid phase extraction work-up efficiently removed HPLC solvent while maintaining chemical purity and overall radiochemical yield and purity. This new HPLC purification and final formulation was completed within 40 min, providing 2.7 ± 0.5 GBq of [11C]ER176 at end of synthesis with 1400 ± 300 GBq/μmol molar activity while meeting all specifications for radiopharmaceutical quality control tests for human research use. • New ternary isocratic semi-preparative HPLC providing improved resolution of [11C]ER176 from non-radioactive impurity. • Identification of non-radioactive impurity that elutes proximal to [11C]ER176 and preliminary mechanistic investigation of its formation. • Purification of [11C]ER176 utilizing solid-phase extraction (SPE) for removal of semi-preparatory HPLC mobile phase. • Production of [11C]ER176 within 40 min, providing 2.7 ± 0.5 GBq at end of synthesis with 1400 ± 300 GBq/μmol molar activity. [ABSTRACT FROM AUTHOR]