Studies on the separation of 90Y from 90Sr by solvent extraction and supported liquid membrane using TODGA: role of organic diluent

An overview of automated flow systems for total and isotopic analysis of strontium and yttrium in samples of environmental interest

Due to the different uses of radioactivity during the last decades, there has been an increase in the concentration of natural and artificial radionuclides in the environment. This, along with some accidents with a high affect public opinion (for example, Chernobyl and Fukushima), have led to the growth and establishment of environmental radioactivity monitoring programs. Currently, trends in legislation and research are focused on the development of accurate, precise, reliable and fast analytical methods with low limits of detection (LOD) for radionuclides determination, such as strontium and yttrium, in environmental samples. In this paper, two comprehensive reviews and four automated analytical systems for total and isotopic determination of yttrium and strontium are presented. The developed methods have been applied in the analysis of environmental samples with low concentrations of these analytes. These methodologies have been automated by exploiting flow analysis techniques, such as multi-syringe flow injection analysis (MSFIA), Sequential injection analysis (SIA) and laboratory-on-valve (LOV) systems, achieving a minimal handling and low consumption of samples and reagents, a significant reduction in waste generation and a high frequency of analysis. In the developed methodologies, some spectrometric methods such as ICP-OES and ICP-MS have been implemented as detection techniques instead of radiometric detectors obtaining a fully automated, low-cost and fast yttrium and strontium determinations.

New strategies for a sustainable 99mTc supply to meet increasing medical demands: Promising solutions for current problems

The continuing rapid expansion of ^99mTc diagnostic agents always calls for scaling up ^99mTc production to cover increasing clinical demand. Nevertheless, ^99mTc availability depends mainly on the fission-produced ⁹⁹Mo supply. This supply is seriously influenced during renewed emergency periods, such as the past ⁹⁹Mo production crisis or the current COVID-19 pandemic. Consequently, these interruptions have promoted the need for ^99mTc production through alternative strategies capable of providing clinical-grade ^99mTc with high purity. In the light of this context, this review illustrates diverse production routes that either have commercially been used or new strategies that offer potential solutions to promote a rapid production growth of ^99mTc. These techniques have been selected, highlighted, and evaluated to imply their impact on developing ^99mTc production. Furthermore, their advantages and limitations, current situation, and long-term perspective were also discussed. It appears that, on the one hand, careful attention needs to be devoted to enhancing the ⁹⁹Mo economy. It can be achieved by utilizing ⁹⁸Mo neutron activation in commercial nuclear power reactors and using accelerator-based ⁹⁹Mo production, especially the photonuclear transmutation strategy. On the other hand, more research efforts should be devoted to widening the utility of ⁹⁹Mo/^99mTc generators, which incorporate nanomaterial-based sorbents and promote their development, validation, and full automization in the near future. These strategies are expected to play a vital role in providing sufficient clinical-grade ^99mTc, resulting in a reasonable cost per patient dose.

Selective permeation of 90Y from a mixture of 90Y/90Sr through diglycolamide impregnated supported liquid membranes

An attempt was made in this work to evaluate a simple flat sheet supported liquid membrane technique for the separation of carrier free ⁹⁰Y from ⁹⁰Sr using two diglycolamide carrier ligands, (i) N,N,N',N'-tetra-n-octyl-diglycolamide (TODGA), and (ii) N,N,N',N'-tetra-(2-ethylhexyl)-diglycolamide (TEHDGA). Various experimental parameters were optimized to get selective transport of ⁹⁰Y over ⁹⁰Sr. At 6 M HNO₃ feed acidity, >95% ⁹⁰Y could be recovered selectively in just 4 h with both the ligands. Under identical experimental conditions, about 0.1% transport of Sr was also recorded which could be completely removed by passing through a Sr selective column to get medical grade ⁹⁰Y pure product. A mathematical model equation was also derived and experimentally validated for predicting the transport of ⁹⁰Y through membrane.

Radionuclide generator-based production of therapeutic 177Lu from its long-lived isomer 177mLu

Background

In this work, a lutetium-177 (¹⁷⁷Lu) production method based on the separation of nuclear isomers, ^177mLu & ¹⁷⁷Lu, is reported. The ^177mLu-¹⁷⁷Lu separation is performed by combining the use of DOTA & DOTA-labelled peptide (DOTATATE) and liquid-liquid extraction.

Methods

The ^177mLu cations were complexed with DOTA & DOTATATE and kept at 77 K for periods of time to allow ¹⁷⁷Lu production. The freed ¹⁷⁷Lu ions produced via internal conversion of ^177mLu were then extracted in dihexyl ether using 0.01 M di-(2-ethylhexyl) phosphoric acid (DEHPA) at room temperature. The liquid-liquid extractions were performed periodically for a period up to 35 days.

Results

A maximum ¹⁷⁷Lu/^177mLu activity ratio of 3500 ± 500 was achieved with [^177mLu]Lu-DOTA complex, in comparison to ¹⁷⁷Lu/^177mLu activity ratios of 1086 ± 40 realized using [^177mLu]Lu-DOTATATE complex. The ¹⁷⁷Lu-^177mLu separation was found to be affected by the molar ratio of lutetium and DOTA. A ¹⁷⁷Lu/^177mLu activity ratio up to 3500 ± 500 was achieved with excess DOTA in comparison to ¹⁷⁷Lu/^177mLu activity ratio 1500 ± 600 obtained when lutetium and DOTA were present in molar ratio of 1:1. Further, the ¹⁷⁷Lu ion extraction efficiency, decreases from 95 ± 4% to 58 ± 2% in the presence of excess DOTA.

Conclusion

The reported method resulted in a ¹⁷⁷Lu/ ^177mLu activity ratio up to 3500 after the separation. This ratio is close to the lower end of ¹⁷⁷Lu/^177mLu activity ratios, attained currently during the direct route ¹⁷⁷Lu production for clinical applications (i.e. 4000–10,000). This study forms the basis for further extending the liquid-liquid extraction based ^177mLu-¹⁷⁷Lu separation in order to lead to a commercial ^177mLu/¹⁷⁷Lu radionuclide generator.

Electronic supplementary material

The online version of this article (10.1186/s41181-019-0064-5) contains supplementary material, which is available to authorized users.