Derivatives of 3,4-hydroxypyridinones have been extensively studied for in vivo Fe³⁺ sequestration. Deferiprone, a 1,2-dimethyl-3,4-hydroxypyridinone, is now routinely used for clinical treatment of iron overload disease. Hexadentate tris(3,4-hydroxypyridinone) ligands (THP) complex Fe³⁺ at very low iron concentrations, and their high affinities for oxophilic trivalent metal ions have led to their development for new applications as bifunctional chelators for the positron emitting radiometal, ⁶⁸Ga³⁺, which is clinically used for molecular imaging in positron emission tomography (PET). THP-peptide bioconjugates rapidly and quantitatively complex ⁶⁸Ga³⁺ at ambient temperature, neutral pH and micromolar concentrations of ligand, making them amenable to kit-based radiosynthesis of ⁶⁸Ga PET radiopharmaceuticals. ⁶⁸Ga-labelled THP-peptides accumulate at target tissue in vivo, and are excreted largely via a renal pathway, providing high quality PET images.

We have quantified trace metal impurities present in ⁶⁸ Ga generator eluant from the widely used Eckert & Ziegler ⁶⁸ Ga generator, and measured the effect of these metal impurities on ⁶⁸ Ga radiolabelling of a THP chelator.

Background: Nanocolloidal human serum albumin radiolabelled with ^99mTc provides a diagnostic radiopharmaceutical for sentinel node lymphoscintigraphy. NanoHSA (Nanotop), a commercially available kit, enables the simple preparation of this radiopharmaceutical via reconstitution with pertechnetate eluted from a generator. Thin-layer chromatography is widely used for determining radiochemical purity in clinical nuclear medicine. Quality control methods recommended by the manufacturer were sometimes reported to yield variable results. Therefore, we proposed and evaluated three alternative thin-layer chromatography methods for the quality control of [^99mTc]Tc-NanoHSA from a commercially available kit. Results: The radiochemical purity of [^99mTc]Tc-NanoHSA determined with all methods was reproducible and met the requirements of the SPC and the European Pharmacopoeia (≥ 95%). Our quality control using iTLC-SG chromatographic paper in methyl ethyl ketone mobile phase identified only free pertechnetate as impurity, resulting in > 99% RCP. The quality control using iTLC-SG in 85% methanol or iTLC-SA in 0.9% NaCl identified an additional small fraction of a hydrophilic impurity, resulting in 95–97% RCP. Glucose was identified as a potential ^99mTc-carrying hydrophilic species contributing to hydrophilic impurities. Conclusion: Our quality control of [^99mTc]Tc-NanoHSA with non-polar mobile phase tended to underestimate the amount of hydrophilic impurities, although without compromising the final quality of the radiopharmaceutical. Alternative TLC methods using aqueous mobile phases enabled a more accurate determination of hydrophilic impurities.

Actinium-225 is a highly radiotoxic alpha-emitting radionuclide, which is currently in the spotlight owing to its promising radiotherapeutic applications in nuclear medicine. Personnel involved in the production and handling of actinium-225 is exposed to a risk of accidental incorporation of this radionuclide. Radiological protection regulations require regular monitoring of incorporation and internal dosimetry assessment for workers manipulating open radioactive sources. Urine is often used as a biological sample for measuring the incorporation of actinides, however it requires a radiochemical separation with a certified metrological tracer to enable quantitative determination. There is no stable, nor sufficiently long-lived radioactive isotopes of actinium to provide a metrological yield tracer. In this article, we propose an application of an ion-imprinted polymer resin to extract actinium-225 from urine employing americium-243 as a radioactive tracer. The radiochemical separation was followed by a quantitative determination with alpha-spectrometry. Solid-phase extraction of both actinides from urine using ion-imprinted polymer resin resulted in good radiochemical yields: 57.7 +/- 16.5% (n = 17) for actinium-225 and 62.8 +/- 18.0% (n = 17) for americium-243. Equivalent recoveries showed that americium-243 is a suitable yield tracer for the determination of actinium-225 with an ion-imprinted polymer resin. Combined with a different measurement technique, this method can be applied for the separation of other isotopes of actinium, such as actinium-227. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).