Novel ion exchange chromatography method for nca arsenic separation

The role of chemistry in accelerator-based production and separation of radionuclides as basis for radiolabelled compounds for medical applications

Radiochemical separations used in large scale routine production of diagnostic and therapeutic radionuclides at a particle accelerator for patient care are briefly outlined. The role of chemistry at various stages of development of a production route of a novel radionuclide, namely nuclear data measurement, high-current targetry, chemical processing and quality control of the product, is discussed in detail. Special attention is paid to production of non-standard positron emitters (e.g. 44gSc, 64Cu, 68Ga, etc.) at a cyclotron and novel therapeutic radionuclides (e.g. 67Cu, 225Ac, etc.) at an accelerator. Some typical examples of radiochemical methods involved are presented.

Adsorption performance and its mechanism of aqueous As(III) on polyporous calcined oyster shell-supported Fe-Mn binary oxide

Fe-Mn binary oxide (FMBO) is a promising adsorbent for As(III) removal through combined adsorption and oxidation. The calcined oyster shell-supported Fe-Mn binary oxide (FMBO/OS) adsorbent was synthesized by the co-precipitation method. Results indicated that the calcined oyster shell, as a carrier, improved the stability of FMBO and its adsorption capacity for As(III). The maximum adsorption capacity of FMBO/OS on As(III) reached 140.5 mg·g^-1 . Under pH 5.0 and 25°C, the removal efficiency of FMBO/OS to As(III) solution (C₀  = 10 mg·L^-1 ) reached 87% within 12 h. Moreover, based on the characterization analyses, the removal mechanisms of As(III) were deduced to include the combined adsorption and oxidation process of FMBO and the synergistic effect of oyster shells. This work provides new insights into synthesizing efficient and green adsorbents to remove aqueous As(III). Meanwhile, it provides technical support for reusing waste biomass materials such as the oyster shell. PRACTITIONER POINTS: FMBO/OS was prepared by a simple hydrothermal co-precipitation method. The carrier alleviates the agglomeration of Fe-Mn oxides. The adsorbent shows a strong adsorption capacity of As(III) and good selectivity. The good results benefit from the synergistic effect of calcium arsenate generation. The prepared adsorbent can adsorb arsenic in real samples.

Separation of 71,72As from alpha particle induced gallium oxide target by solid cation and anion exchangers, DOWEX-50 and DOWEX-1

46.0 MeV alpha particle induced reaction on gallium oxide target results production of no-carrier-added (NCA) ^71,72As and ⁶⁷Ga tracer. ^71,72As were separated from the target matrix by solid liquid extraction (SLX) using two different exchangers, Dowex-1 and Dowex-50. At best condition of 0.2 g Dowex-1 + 6 M HCl and 0.2 g Dowex-50 + 10^-3 M HCl bulk gallium was completely extracted leaving behind NCA ^71,72As in the aqueous phase. Dowex-50 was found to be more suitable and offered high separation factor, 3.2 × 10⁵.

Separation of no-carrier-added 71,72As from 46 MeV alpha particle irradiated gallium oxide target

No-carrier-added (NCA) 71,72As radionuclides were produced by irradiating gallium oxide target by 46 MeV α-particles. NCA 71,72As was separated from the target matrix by liquid-liquid extraction (LLX) using trioctyl amine (TOA) and tricaprylmethylammonium chloride (aliquat-336) diluted in cyclohexane. The bulk gallium was quantitatively extracted into the organic phase leaving 71,72As in the aqueous phase. Complete separation was observed at 3 M HCl + 0.1 M TOA and 2 M HCl + 0.01 M aliquat-336.

Expanding PET-applications in life sciences with positron-emitters beyond fluorine-18

Positron-emission-tomography (PET) has become an indispensable diagnostic tool in modern nuclear medicine. Its outstanding molecular imaging features allow repetitive studies on one individual and with high sensitivity, though no interference. Rather few positron-emitters with near favourable physical properties, i.e. carbon-11 and fluorine-18, furnished most studies in the beginning, preferably if covalently bound as isotopic label of small molecules. With the advancement of PET-devices the scope of in vivo research in life sciences and especially that of medical applications expanded, and other than "standard" PET-nuclides received increasing significance, like the radiometals copper-64 and gallium-68. Especially during the last decades, positron-emitters of other chemical elements have gotten into the focus of interest, concomitant with the technical advancements in imaging and radionuclide production. With known nuclear imaging properties and main production methods of emerging positron-emitters their usefulness for medical application is promising and even proven for several ones already. Unfortunate decay properties could be corrected for, and β⁺-emitters, especially with a longer half-life, provided new possibilities for application where slower processes are of importance. Further on, (bio)chemical features of positron-emitters of other elements, among there many metals, not only expanded the field of classical clinical investigations, but also opened up new fields of application. Appropriately labelled peptides, proteins and nanoparticles lend itself as newer probes for PET-imaging, e.g. in theragnostic or PET/MR hybrid imaging. Furthermore, the potential of non-destructive in-vivo imaging with positron-emission-tomography directs the view on further areas of life sciences. Thus, exploiting the excellent methodology for basic research on molecular biochemical functions and processes is increasingly encouraged as well in areas outside of health, such as plant and environmental sciences.

Arsenic removal from highly-acidic wastewater with high arsenic content by copper-chloride synergistic reduction

A synergistic combination of chloride and copper powder was proposed as a new method to reductively remove arsenic from highly-acidic wastewater with high arsenic content (HAWA). As(III) was reduced to As(0) by copper powder in the presence of chloride and were effectively removed from HAWA. The procedure to remove arsenic was optimized as follows: initial H⁺ concentration of 5 mol L^-1, Cu-to-As molar ratio of 8, Cl-to-As molar ratio of 10, a reaction temperature of 60 °C, copper powder particle size of 68-24 μm, and a stirring speed of 300 r min^-1. Under these optimal conditions, the removal rate of arsenic was close to 100%. Kinetics results suggested that the arsenic removal process was controlled by both diffusion and chemical reactions with an apparent activation energy of 29.78 kJ mol^-1. The XRD results showed that the removed arsenic in the residue existed primarily in the form of AsCu₃ alloy.

Optimization of the reduction of 74As(V) to 74As(III) and of the labelling of dithiol dihydrolipoic acid

The radiochemical separation of n.c.a. arsenic on its own or for radio-labelling purposes usually involves the issue of reducing arsenic(V). Numerous approaches for reducing pentavalent arsenic have been examined. A novel HPLC method has also been presented for accessing the efficiency of the reduction in terms of *As(III)/*As(V). Labelling with trivalent radioarsenic seems to be a promising research field to access new radiopharmaceuticals, for example, using arsenic as a surrogate for phosphorus. Moreover, as a model system, the labelling reaction of *As(III) with dihydrolipoic acid has been systematically optimized.