Radiohimiâ

In the course of prolonged interaction in the system consisting of [⁹⁹Тс(hfa)(СО)₄] (hfa is the anion of 1,1,1,5,5,5-hexafluoroacetylacetone), triphenylphosphine (РРh₃) or pyridine (py), and CCl₄, the hfa anion is gradually displaced by the chloride ion with the formation of the complexes fac- and mer-[⁹⁹ТсСl(СО)₃(РРh₃)₂] and fac-[⁹⁹ТсСl(СО)₃(py)₂]. The crystal and molecular structures of the complexes were determined. The complex fac [⁹⁹ТсСl(СО)₃(РРh₃)₂] is the first structurally confirmed example of technetium(I) tricarbonyl bis(triphenylphosphine) complexes of facial structure.

The conjugation of N-succinimidyl-4-[¹⁸F]fluorobenzoate ([¹⁸F]SFB), a widely used radiosynthon for labeling biologically complex molecules for use as radiopharmaceuticals (RPs) in positron emission tomography (PET), with a model tripeptide, glutathione (GSH), was studied. [¹⁸F]SFB was prepared using the previously developed method of direct copper(II)-mediated radiofluorination of arylpinacolboronate as a labeling precursor. The efficiency of the conjugation of [¹⁸F]SFB, which was recovered from the reaction mixture by solid-phase extraction (SPE) on disposable cartridges, with GSH in an acetonitrile/phosphate buffered mixture with pH 8.4 depended on the ratio of the aqueous and nonaqueous phases and the peptide concentration. With equal volumes of the components (0.5 mL) and a GSH concentration of 1.0 mg/mL, the conjugation yield of 97% was achieved. This serves as further evidence of the efficiency of SPE purification, which removes chemical impurities that could otherwise compete in the conjugation reaction. This purification method using disposable cartridges can be easily adapted to any automated modules, including cassette ones. This contributes to the more effective use of [¹⁸F]SFB in synthesizing radiopharmaceuticals based on complex biomolecules.

The influence of the content of structure-forming components of sodium aluminum iron phosphate glass on its phase composition, structure, and resistance to leaching at elevated temperatures as necessary characteristics of vitrified iron-containing high-level waste during its deep disposal was studied. It was found that the samples studied (mol %), 40.0Na₂O–12.5Al₂O₃–12.5Fe₂O₃–35.0P₂O₅, 35.0Na₂O–12.5Al₂O₃–12.5Fe₂O₃–40.0P₂O₅, and 35.0Na₂O–10.0Al₂O₃–10.0Fe₂O₃–45.0P₂O₅, are represented by a single amorphous glass phase and have high hydrothermal stability. The leaching rate of sodium and phosphorus from the above samples under semidynamic (on the 28th day) and dynamic (on the 10th day) conditions at 90 and 95°C, respectively, was about 10⁻⁵ g/(cm² day), that of aluminum, within the range (2–10) × 10⁻⁶ and (0.6–2) × 10⁻⁵ g/(cm² day), respectively, and that of iron, within the range (7–12) × 10⁻⁷ and (0.4–3) × 10⁻⁶ g/(cm² day), respectively.

The study evaluated the possibility and efficiency of sorption of artificial (¹³⁷Cs), natural (²¹⁰Pb, ²¹⁰Po, ²²⁶Ra, ²²⁸Ra, ²³⁴Th), and cosmogenic (⁷Be, ³²P, ³³P) radionuclides from large volumes of seawater using various types of sorbents. The sorption of the radionuclides studied was scaled up and optimized, with optimal parameters for sorption concentration being established. Based on the obtained data, a comprehensive method was developed and tested for simultaneous concentration of a wide range of radionuclides from seawater using the most efficient sorbents. The study demonstrated the possibility of concentrating multiple radionuclides from a single sample, which significantly simplifies sampling procedures and field research.