Quality assurance of 61Cu using ICP mass spectroscopy and metal complexation

Introduction 61Cu (T1/2 = 3.33 hr, Eβ= 1.22 MeV, 61.4 %) is an attractive isotope for positron emission tomography (PET) radiopharmaceutical agents such as ATSM and PTSM. Various separation processes have been reported for the production of 61Cu on a medium cyclotron using 13–22 MeV protons on natural and enriched 64Zn target materials [1,2]. This work, investigates production of 61Cu using both natural and enriched 64Zn targets and its separation. Three types of resins were used to assess for their efficiency and speed to separate the desired 61Cu from the 66,67,68Ga and 64Zn and for the recycling of 64Zn target material. The effective specific activity of purified 61Cu, was determined by ICP-MS and its titration with various polyaza and polycarboxylate complexing ligands. Material and Methods 1. Production and Separation Targets were irradiated by proton beam of IBA cyclotron 18/18MeV via the 64Zn(p,α) 61Cu and natZn(p,x) 61Cu reactions using an enriched 64Zn foil(15×15×0.05mm, ~50 mg) and natural foil (diameter 25 mm, 0.05 mm,~ 60 mg). Thirty minute irradiations were conducted with incident proton energies between 11.7–12.0 MeV and beam currents of 20 and 40 µA. Irradiated Zn targets were dissolved in 8M HCl at 150 oC then evaporated to dryness. Trace water to the resultant residue (twice) and resultant solutions evaporated to dryness. The residue was re-dissolved in 2ml of 0.01M HCl before loading onto a Cu-resin column (FIG. 1) Zn and Ga isotopes were collectively eluted using 30 ml of 0.01M HCl. The Cu was then removed using 1.5 ml of 8M HCl and passed directly onto a cation exchange followed by an anion exchange column. An additional 3 ml of 8M HCl was used to rinse the cation exchange column and ensure quantitatively removal of Cu (II) ions. The Cu was finally eluted from the anion exchange column using 3 ml of 2M HCl. The Cu solution was heated up at 150 oC until evaporated to dryness and 61Cu final product dissolved in 400–800 μL of 0.01M HCl. 2. Specific activity of 61Cu The specific activity (GBq/µmol) of the purified 61Cu was determined by ICP-MS and compared with that determined using dota, nota and di-amsar complexing ligands. For each 61Cu production run aliquot of final solution (100 µL) was left to decay before dilut-ing to 10 mL with 10% HNO3. Decayed samples were sent to ChemCentre (Curtin University) for ICP-MS analysis. Each sample was analysed for Cu, Al, Ca, Co, Fe, Ga, Ni, Si, and Zn, which are known to compete with Cu2+ for ligand complexation. Effective specific activity of the 61Cu was deter-mined by titrating various known concentration of ligands with 61Cu solution. The method is detailed in the literature [3]. Briefly, varying concentrations of each ligand was prepared in 0.1M sodium acetate buffer pH 6.5 to a total volume 20 µL. Fixed concentration of diluted 61Cu (0.01M HCl) in 10 µL was added to each ligand solution. The mixtures were vortexed then left to incubate at the room temperature for 30 mins. Two uL aliquots were withdrawn (in triplicate) from each reaction mixture and spot-ted on ITLC –SA. [Mobile phase: 0.1M NaCl: 0.1M EDTA (9:1) for Cu2+ and diamsar mixtures: Rf 0.8 free Cu2+ and 0.1M sodium acetate pH 4.5: H2O: MeOH: ammonium hydroxide (20:18:2:1 v/v) for Cu2+ dota and nota mixtures: Rf >0.8 Cu-dota and Cu-nota Rf < 0.2 free Cu2+]. Complexation of the 61Cu with each ligand was complete within 30 mins at room temperature. Concentration of Cu2+ was deter-mined from the 50% labelling efficiency. Results and Conclusion 1. Production and Separation The radioisotopes production from natZn target must be minimized by the optimum proton energy to reduce a radiation dose in the final product. The excitation functions of 66,67,68Ga ,65Zn and 61Cu are shown in FIG. 2. Proton beam energy of 11.7 MeV was used for both Zn targets to minimise the production of Ga isotopes and prevent formation of 65Zn. For the enriched 64Zn target (99.30%) higher proton energy could be used for the production of 61Cu allowing for increased yields and reduce radio contaminants. Previously, we used anion and cation exchange resin as described in the literature to separate the 61Cu [1]. Unfortunately the literature method was too long (up to 3 hours) and requiring high concentration of HCl and long evaporation times compromising achievable yields [4]. Thieme S. et al., 2013 [2] reported the successful use of Cu-resin for the separation of Cu radioisotopes and it was of interest to the current work to test this material for the separation of 61Cu in our hands. A cation, anion exchange and Cu-resin were combined into closed system to separate the 61Cu within 30 mins (FIG. 1). The system is designed to contain the transfer of solutions be-tween each column using simple plunger to force solution through and between each column. This system afforded an easy, reliable and fast separation of 61Cu that could be completed within 30 min. 2. Specific activity The specific activity of 61Cu was determined using ICP-MS and by titration with three ligands is summarized in TABLE 1. The ICP-MS data show values ranging from 9.2 to 32.4 GBq/μmol for 8 production runs. Specific activity determine using nota and dota were in all cases lower than the ICP MS data indicating some interference from the other metal ion contaminates such as Fe(ii/Iii), Ni (II), Ca (II), Zn (II), Ga (III). The specific activity determine using diamsar, which is known to be highly selective for Cu(II) (and Zn(II) and Fe(III)) in the presence of alkali and alkaline earth ions gave values significantly higher effective specific activity than that obtained using ICP MS. Variations in values can be explained by presence of contaminating metal ions

Excitation functions of natZn(p,x) nuclear reactions with proton beam energy below 18 MeV

Introduction We measured the excitation functions of natZn (p,x) reactions up to 17.6 MeV using the stacked-foils activation technique. High-purity natural zinc (and copper) foils were irradiated with proton beams from an 18MeV medical cyclotron, the predominant purpose of which is to provide a routine regional service for clinical PET radiopharmaceuticals. Thick-target integral yields were also deduced from the measured excitation functions of the produced radioisotopes. These results were compared with the literature and were found to be in good agreement with most but not all published reports. Material and Methods The excitation functions of the natZn(p,x) reactions were measured by the well-known stacked foil technique (1). High purity zinc foils (99.99%; Goodfellow Metals Ltd., UK) each thickness 0.025 ± 0.003 mm with isotopic composition 64Zn (48.6 %), 66Zn (27.9 %), 67Zn (4.1 %), 68Zn (18.8 %) and 70Zn (0.6 %) were loaded into a solid targetry system on a 300-mm external beam line utilising helium-gas and chilled water to cool the target body (2). A typical foils stack consisted of repeated units of four Zn foils interleaved with a high purity copper foil (0.025 ± 0.004 mm); the latter for monitoring beam flux using the well documented 63,65Cu(p,n)63,65Zn reactions. Foil stacks were irradiated with a primary beam of energy 17.6 MeV, accounting for beam degradation by an obligatory 0.0250 ± 0.0005 mm-thick Havar® foil beam-line vacuum window. Irradiation was for 3 min at a beam current of 5 µA. Activated foils were measured using cryo high-purity Ge γ-spectroscopy to quantify the product radionuclides 61Cu, 66Ga, 67Ga and 65Zn. Radioactivity of each isotope was corrected to end of bombardment (EOB). Results and Conclusion New cross-sectional data for natZn(p,x) reactions up to 17.6 MeV yielding 61Cu, 66Ga, 67Ga and 65Zn isotopes were measured in independent replicated (N = 3) experiments. Results were generally in good agreement with published data. These isotopes can potentially be used in clinical or preclinical studies, following appropriate chemical separations of the zinc, gallium and copper (3). The FIG. 1 shows thick-target integral yields calculated from excitation functions measured in this study. It can be calculated (for example) that useful activities of 61Cu can be produced using a 100 µm thick natZn target in a beam provided by a standard medium-energy medical cyclotron. For example, an irradiation at 40 µA for 2 hr at 17.6 MeV would produce approximately 1.7 GBq of 61Cu at EOB. Such currents are readily achievable using solid targetry in our laboratory (2)

Guidelines for the definition of operational management units

The objective of fisheries management is the sustainable exploitation of the fish resources over the extent of their spatial distribution. Along with the Common Fisheries Policy (CFP) objectives, the socio-economic viability of the fisheries exploiting the resource is also to be achieved. To reach these aims, managers need to define the management units they are going to work with. For the purpose of GEPETO project, we define a management unit (MU) as the set of fishing fleets exploiting a common pool of fish resources with strong spatial overlapping and sharing of habitats, which make them being typically fished together. In other words, a MU is the set of fishing fleets exploiting a common fish community over their spatial distribution. MUs have to be defined by the fish community, by the spatial range of distribution of the fish community, and by the set of fishing fleets sharing the exploitation of the fish communityL'objectif de gestion de la pêche est l'exploitation durable des ressources halieutiques sur l'étendue de leur répartition spatiale. Avec la nouvelle Politique Commune de la pêche (PCP) l' objectif de la viabilité socio-économique des pêcheries exploitant la ressource doit également être réalisé. Pour l'atteindre, les gestionnaires doivent définir des unités de gestion. Les partenaires du projet GEPETO, définissent une unité de gestion (MU) comme l'ensemble des flottes de pêche exploitant un pool commun de ressources halieutiques disponibles dans des habitats communs, ce qui les rend très imbriquées. En d'autres termes, un MU est l'ensemble des flottes de pêche exploitant une communauté de poissons ordinaires sur leur répartition spatiale. La MU peu être définie par la communauté de poissons, par la gamme spatiale de la distribution de la communauté de poissons, et par l'ensemble des flottes de pêche qui partagent l'exploitation de la communauté de poissons

Thermodynamic modelling of phase evolution in alkali-activated slag cements exposed to carbon dioxide

Carbonation of cementitious materials induced by their interaction with atmospheric CO2 is one of the main degradation mechanisms threatening their durability. In this study, a novel thermodynamic model to predict the phase evolution of alkali-activated slags exposed to an accelerated carbonation environment is presented. This model predicts the phase assemblages of carbonated alkali-activated slag cements, as a function of CO2 uptake under 1 v/v % CO2 conditions, considering the bulk slag chemistry and activators used. The changes taking place during the carbonation process regarding the physicochemical properties of the main binding gel, an alkali calcium aluminosilicate hydrate (C-(N)-A-S-H), the secondary reaction products CaAl and MgAl layered double hydroxides, and amorphous aluminosilicate gels, were simulated and discussed. The predictions of the thermodynamic model are in good agreement with experimental data retrieved from the literature, demonstrating that this is a valuable tool for predicting long-term performance of alkali-activated slag cements

Characterization and standardization of the Atlantic albacore French pelagic trawl fishery

We compiled and analysed logbook data from the French trawl albacore fishery covering the period 1991-2015. The dataset comprised catch and effort data for the French fleet operating in the Bay of Biscay and Celtic Sea, as well as spatiotemporal and gear characteristics. Generalized linear modelling was used to model spatial, seasonal, environmental, and gear covariates of fleet CPUE rates. A long-term index of relative abundance is provided that can be integrated into the stock assessment of North Atlantic albacore. The analysis revealed higher albacore CPUE associated with relatively low sea surface temperature and distinct seasonal effects. The derived abundance trend for the French trawl fishery agreed with the estimated time series of stock abundance from recent assessments

Optimal milling conditions for carbon/epoxy composite material using damage and vibration analysis

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INFLUENCE OF BOTH RAKE AND FLANK FACES METAL WORKING FLUID (MWF) STRATEGIES ON MACHINABILITY OF Ti-6Al-4V ALLOY

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Influence of trans-1,2-diaminocyclohexane structure and mixed carboxylic/phosphonic group combinations on samarium-153 chelation capacity and stability

A simple procedure was developed to compare chelating agents for 153Sm complexes as a preliminary step to synthesise bifunctional analogues. Several variables affecting the efficiency of complex stability were investigated, such as the pre-organisation concept, cavity size, and the nature of coordination sites. Four semi-rigid agents incorporating carboxylic and/or phosphonic groupings fixed at trans-1,2-diaminocyclohexane were evaluated for their 153Sm chelation properties, and competition studies were performed. Data on the stability of the best chelating agent compound 3: trans-cyclohexane-1,2-bis(aminomethylphosphonic)-N,N′-bis(ethyl-2- iminodiacetic acid) in human serum are presented

Synthesis of New Semi-Rigid Chelating Agents for Samarium-153.

Abstract not availableJRC.E-Institute for Transuranium Elements (Karlsruhe

Machining carbon fibre reinforced plastics: lead angle effect

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