Tc Generator Research Articles

Sorption behavior of low specific activity 99Mo on Ti- and Zr-xerogels as an alternative to fission-based 99Mo/99mTc generators

Abstract In order to contribute to the sufficient supply of clinical 99mTc(VII), the sorption behavior of neutron-produced 99Mo(VI) was investigated on synthetized single and binary Ti and Zr xerogels treated at different temperatures, under normal operating conditions. Materials were prepared by the sol–gel method and characterized by several techniques. Sorption batch systems were performed using 99Mo radiotracer to determine the metallic affinity as a function of pH, and a methodology was developed in order to obtain the maximum capacities by surface saturation, where the Ti-388, TiZr-388 (3:1) and Zr-388 samples showed the most noteworthy sorption behaviors (33.1 ± 0.34 mg/g at pH ∼ 6.0, 31.7 ± 0.27 mg/g at pH ∼ 6.5, and 23.5 ± 0.61 mg/g at pH ∼ 6.8, respectively). The molybdenum-99 sorption behavior was also studied by fitting to the Freundlich and Langmuir models, and all xerogels could be described as heterogeneous materials with favorable 99Mo sorption properties. Finally, preliminary studies of clinical-scale 99Mo/99mTc generators were performed, the results revealed the next maximum 99mTc elution yield order Ti-388 (89.6 %) > TiZr-388 (3:1) (86.7 %) > Zr-388 (77.7 %).

Utilization of high specific activity 99Mo for assessing the active manganese oxide as a potential material for 99Mo/99mTc generator

Abstract The hydrothermal preparation of active MnO2 via KMnO4 and MnSO4.H2O as inorganic forerunners is demonstrated, and it is evaluated as an adsorbent for the 99Mo produced by 235U fission. The structure and morphology of MnO2 were distinguished using various methods such as FTIR spectrum, FESEM, EDX, XRD, TGA. The 99Mo adsorption conduct on active manganese oxide was investigated, and the Mo uptake capacity was determined using static and dynamic techniques, and it was found to be 22.8 ± 1 and 6.72 ± 0.3 mg/g MnO2, respectively. This sorbent material was used in preliminary studies to prepare a 99Mo/99mTc generator. 99mTc eluted from the prepared generator was estimated to be 78–82 % with a low 99Mo breakthrough (0.002 %) and acceptable radiochemical, radionuclidic, and chemical purities.

N-Centered Tripodal Phosphine Re(V) and Tc(V) Oxo Complexes: Revisiting a [3 + 2] Mixed-Ligand Approach.

N-Triphos derivatives (NP3R, R = alkyl, aryl) and asymmetric variants (NP2RXR′, R′ = alkyl, aryl, X = OH, NR2, NRR′) are an underexplored class of tuneable, tripodal ligands in relation to the coordination chemistry of Re and Tc for biomedical applications. Mixed-ligand approaches are a flexible synthetic route to obtain Tc complexes of differing core structures and physicochemical properties. Reaction of the NP3Ph ligand with the Re(V) oxo precursor [ReOCl3(PPh3)2] generated the bidentate complex [ReOCl3(κ2-NP2PhOHAr)], which possesses an unusual AA’BB’XX’ spin system with a characteristic second-order NMR lineshape that is sensitive to the bi- or tridentate nature of the coordinating diphosphine unit. The use of the asymmetric NP2PhOHAr ligand resulted in the formation of both bidentate and tridentate products depending on the presence of base. The tridentate Re(V) complex [ReOCl2(κ3-NP2PhOAr)] has provided the basis of a new reactive “metal-fragment” for further functionalization in [3 + 2] mixed-ligand complexes. The synthesis of [3 + 2] complexes with catechol-based π-donors could also be achieved under one-pot, single-step conditions from Re(V) oxo precursors. Analogous complexes can also be synthesized from suitable 99Tc(V) precursors, and these complexes have been shown to exhibit highly similar structural properties through spectroscopic and chromatographic analysis. However, a tendency for the {MVO}3+ core to undergo hydrolysis to the {MVO2}+ core has been observed both in the case of M = Re and markedly for M = 99Tc complexes. It is likely that controlling this pathway will be critical to the generation of further stable Tc(V) derivatives.

Use of 99m Tc in The Field of Radiofarmation: A Review

A B S T R A C TTechnetium-99m ( 99m Tc) has been applied in nuclear medicine as a radiopharmacyfor both diagnosis and therapy. 99m Tc is obtained from a 99 Mo/ 99m Tc (half-life 66 h)generator in the form of sodium pertechnetate (Na[ 99m TcO 4 ]) by decaying to 99 Tc for 6hours and emitting gamma energy rays (Eɤ = 140 keV). This radionuclide has anelectron configuration of 4d 5 5s 2 , which will form complexes with different ligandsand have oxidation rates from +1 to +7. The coordinated complex of technetium-99mhas been utilized in nuclear medicine in tissues and organs (thyroid, red and whiteblood cells, kidneys, brain, myocardial, and bone). The resulting kit production musthave based on Good Manufacturing Practice, which consists of batch planning,washing, sterilization of glassware and stopper, starting material, preparation oflarge quantities of the solution, sterile filtration, dispensing, crimping, a summary ofprocess control, quarantine, packaging and leaving the production premises.

Molybdenum-99 (<sup>99</sup>Mo) Adsorption Profile of Zirconia-Based Materials for <sup>99</sup>Mo/<sup>99m</sup>Tc Generator Application

Technetium-99m ( 99m Tc) plays a major role in diagnostic nuclear medicine and has not yet been replaced with any other radionuclides. It is available through the 99 Mo/ 99m Tc generator. The use of low-specific-activity 99 Mo for 99 Mo/ 99m Tc generator application requires high adsorptive capacity sorbents. This study focused on the determination of 99 Mo adsorption capacity of several zirconia materials, namely monoclinic nanozirconia , orthorhombic nanozirconia , sulfated zirconia, and phosphated zirconia. These materials were synthesized by using the sol-gel method and characterized using FT-IR spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS). The determination of 99 Mo adsorption capacity of these materials was carried out by soaking the materials in a Na 2 99 MoO 4 solution with pH of 3 and 7, at temperatures ranging from room temperature to 90 °C, for 1 and 3 hours. The results indicated that monoclinic nanozirconia has a 99 Mo adsorption capacity of 76.9 mg Mo/g, whereas orthorhombic nanozirconia , sulfated zirconia, and phosphated zirconia have 99 Mo adsorption capacities of 150.1 mg Mo/g, 15.58 mg Mo/g, and 12.74 mg Mo/g, respectively. It appears that orthorhombic nanozirconia has the highest 99 Mo adsorption capacity among the synthesized materials and can be applied as a candidate material for the 99 Mo/ 99m Tc generator.

Different effects of latent heat in planetary boundary layer and cloud microphysical processes on Typhoon Sarika (2016)

Three simulation experiments were conducted on Typhoon (TC) “Sarika” (2016) using the WRF model, different effects of the latent heat in planetary boundary layer and cloud microphysical process on the TC were investigated. The control experiment well simulated the changes in TC track and intensity. The latent heat in planetary boundary layer or cloud microphysics process can affect the TC track and moving speed. Latent heat affects the TC strength by affecting the TC structure. Compared with the CTL experiment, both the NBL experiment and the NMP experiment show weakening in dynamics and thermodynamics characteristics of TC. Without the effect of latent heat, the TC cannot develop upwards and thus weakens in its intensity and reduces in precipitation; this weakening effect appears to be more obvious in the case of closing the latent heat in planetary boundary layer. The latent heat in planetary boundary layer mainly influences the generation and development of TC during the beginning stage, whereas the latent heat in cloud microphysical process is conducive to the strengthen and maintenance of TC in the mature stage. The latent heat energy of the cloud microphysical process in the TC core region is an order of magnitude larger than the surface enthalpy. But the latent heat release of cloud microphysical processes is not the most critical factor for TC enhancement, while the energy transfer of boundary layer processes is more important.

Relationship between Antarctic Oscillation and the genesis activity of the yearly latest tropical cyclone in the western North Pacific

AbstractWe find a significant negative correlation between the Antarctic Oscillation (AAO) and the genesis longitude of the last TC of the year (hereafter the last TC) in the western North Pacific (WNP). We also find that the mean longitude of the last TC genesis has experienced a significant westward shift since 1997–1998. That means both a positive AAO phase and AAO phase of the recent epoch (1998–2015) favour the last TC occurring more frequently in the western part of the WNP. Thus, we compared the differences between the positive and negative AAO phases on interannual time scale and the epochal differences between the 1998–2015 and 1983–1997 periods to find the common factors responsible for the more frequent occurrence of the last TCs in the western WNP. The common differences in the 850 hPa stream flows reveal that an anomalous cyclone occurs in the South Indian Ocean, whereas an anomalous anticyclone appears in the WNP. The anomalous northerlies from the Southern Indian Ocean anomalous cyclone move northward, enhancing the cross‐equatorial flows and associated westerlies. The enhanced anomalous westerlies extend eastward and meet the anomalous easterlies originated from the WNP anomalous anticyclone at the South China Sea (SCS). As a result, the anomalous cyclones are strengthened in the SCS and around the Philippines. Further analysis of the differences in the outgoing longwave radiation, 850 hPa relative vorticity, 200–850 hPa vertical wind shear, sea surface temperature, horizontal divergence, 500 hPa omega and velocity potential and divergent winds between the two phases and the two epochs confirm that favourable environments for generation of the last TC take place in the western WNP during the positive AAO phase and in the 1998–2015 epoch.

Influence of Contact Time on Loading 99Mo(n,γ) with Alumina Column in 99Mo / 99mTc Generator

<p>Alumina is usually used for <sup>99</sup>Mo absorbers obtained from <sup>235</sup>U fission product because the use of <sup>235</sup>U is getting limited, and as an alternative <sup>99</sup>Mo obtained from natural MoO<sub>3</sub> irradiation was used. The problem is that <sup>99</sup>Mo produced was not carrier-free as <sup>99</sup>Mo from <sup>235</sup>U fission product because not all MoO<sub>3</sub> is activated to <sup>99</sup>Mo, then it is necessary to know the effect of contact time when loading <sup>99</sup>Mo into the alumina column. To find out the effect of contact time, the experiment was carried out using <sup>99</sup>Mo pH 4, acid alumina column, contact time was varied between 1 to 60 minutes with interval of 15 minutes, and the column was eluted using 2 kinds of eluent namely 0.9% NaCl and MEK. The elution of <sup>99</sup>Mo/<sup>99m</sup>Tc generator is performed 3 times, days 1, 2 and 3. The results showed that the performance of alumina in absorbing <sup>99</sup>Mo influenced by time. The optimal contact time is 15 minutes for 0.9% NaCl solution and 45 minutes for MEK. The amount of <sup>99</sup>Mo breakthrough (µCi<sup>99</sup>Mo/mCi<sup>99m</sup>Tc) from the alumina column increases with elution time both using 0.9% NaCl or MEK. The <sup>99m</sup>Tc eluate obtained from this study does not meet standard requirements. The use of a tandem column is needed to prevent <sup>99</sup>Mo breakthrough on the <sup>99</sup>Mo/<sup>99m</sup>Tc generator to get the <sup>99m</sup>Tc which meet standard requirement.</p>

Solid state synthesis of mesoporous alumina: A viable strategy for preparation of an advanced nanosorbent for 99Mo/99mTc generator technology

Abstract Solid state reactions are becoming increasingly relevant as a technique for clean and efficient synthesis of advanced materials of immense technological relevance. Adsorption based column chromatographic processes are among of the most viable routes for radiochemical separation of medically important radioisotopes for clinical benefits. The fundamental and great challenge in this regard lies in development of highly efficient sorbent materials. Owing to their intrinsically high surface area and large pore volume, ordered mesoporous metal oxides may be the answer in the future for column chromatographic radiochemical separations. This work reports the synthesis of mesoporous alumina with greatly enhanced textural characteristics through solid state reaction of aluminium isopropoxide with glucose, followed by high temperature calcination. The nanostructured material (2–4 nm crystallite size) could be synthesized with large surface area (287 ± 16 m 2 /g) and narrow pore size distribution with mean pore radius of 1.8 ± 0.3 nm. When evaluated as Mo adsorbent for use in preparation of 99 Mo/ 99m Tc generator, mesoporous alumina displayed >10 times higher sorption capacity compared to conventionally used bulk alumina. A clinical-scale 99 Mo/ 99m Tc generator (20.4 GBq) was developed using this sorbent material. Technetium-99 m could be regularly eluted from this generator over a prolonged period of 2 weeks with >80% elution yield and it met all the requirements for clinical use. Overall, this study is expected provide inspiration to explore the relatively new terrain of solid state synthesis for large-scale preparation of ‘next generation’ sorbent materials for widespread utilization in radionuclide generator technology.

Internal radiation dose assessment of radiopharmaceuticals prepared with cyclotron-produced 99m Tc.

Technetium-99m (99m Tc) is the radioisotope most widely used in diagnostic nuclear medicine. It is readily available from 99 Mo/99m Tc generators as the β- decay product of the 99 Mo (T½ =66h) parent nuclide. This latter is obtained as a fission product in nuclear reactors by neutron-induced reactions on highly enriched uranium. Alternative production routes, such as direct reactions using proton beams on specific target materials [100 Mo(p,2n)99m Tc], have the potential to be both reliable and relatively cost-effective. However, results showed that the 99m Tc extracted from proton-bombarded 100 Mo-enriched targets contains small quantities of several Tc radioisotopes (93m Tc, 93 Tc, 94 Tc, 94m Tc, 95 Tc, 95m Tc, 96 Tc, and 97m Tc). The aim of this work was to estimate the dose increase (DI) due to the contribution of Tc radioisotopes generated as impurities, after the intravenous injection of four radiopharmaceuticals prepared with cyclotron-produced 99m Tc (CP-99m Tc) using 99.05% 100 Mo-enriched metallic targets. Four 99m Tc radiopharmaceuticals (pertechnetate, sestamibi (MIBI), hexamethylpropylene-amine oxime (HMPAO) and disodium etidronate (HEDP)) were considered in this study. The biokinetic models reported by the International Commission on Radiological Protection (ICRP) for each radiopharmaceutical were used to define the main source organs and to calculate the number of disintegrations per MBq that occurred in each source organ (Nsource ) for each Tc radioisotope present in the CP-99m Tc solution. Then, target organ equivalent doses and effective dose were calculated for each Tc radioisotope with the OLINDA/EXM software versions 1.1 and 2.0, using the calculated Nsource values and the adult male phantom as program inputs. Total effective dose produced by all Tc isotopes impurities present in the CP-99m Tc solution was calculated using the fraction of total activity corresponding to each radioisotope and compared with the effective dose delivered by the generator-produced 99m Tc. In all cases, the total effective DI of CP-99m Tc radiopharmaceuticals calculated with either versions of the OLINDA software was less than 10% from 6 up to 12h after EOB. 94m Tc and 93m Tc are the Tc radioisotopes with the highest concentration in the CP-99m Tc solution at EOB. However, their contribution to DI 6h after EOB is minimal, due to their short half-lives. The radioisotopes with the largest contribution to the effective DI are 96 Tc, followed by 95 Tc and 94 Tc. This is due to the types of their emissions and relatively long half-lives, although their concentration in the CP-99m Tc solution is five times lower than that of 94m Tc and 93m Tc at the EOB. The increase in the radiation dose caused by other Tc radioisotopes contained in CP-99m Tc produced as described here is quite low. Even though the concentrations of the 94 Tc and 95 Tc radioisotopes in the CP-99m Tc solution exceed the limits established by the European Pharmacopoeia, CP-99m Tc radiopharmaceuticals could be used in routine nuclear medicine diagnostic studies if administered from 6 to 12h after the EOB, thus maintaining the effective DI within the 10% limit.

A Study on the Condition Analysis and Improvement of Domestic Medical 99 Mo/ 99m Tc Generators Self-disposal

A Study on the Condition Analysis and Improvement of Domestic Medical 99 Mo/ 99m Tc Generators Self-disposal

Redox interactions of technetium with neptunium in acid solutions

Redox interaction of reduced technetium forms and technetium(VII) with neptunium(III), neptunium(IV) and neptunium(VI) have been investigated using electrochemical and spectroscopic (Vis–NIR) techniques. The neptunium species most stable in 4 M H2SO4, i.e. Np(IV) ions, do not reduce Tc(VII) in contrast to Np(VI) ions which oxidize Tc(IV) species to Tc(VII). The interaction of pertechnetates with Np(III) leads to formation of Tc(IV) species. The Vis–NIR measurements showed the generation of intermediate Tc(V) and Np(V) forms during the oxidation of Tc(IV) and competitive reduction of Np(VI). Tc(V) and Np(V) forms are characterised by the bands at 460 and 980 nm respectively.

Synthesis of Nano-α-Al2O3 for 99Mo Adsorbent

The fission-product 99 Mo, having a high specific activity, is commonly used in alumina-based 99 Mo /99m Tc generator. Due to the limitation on the use of fission-product 99 Mo, an alternative route for 99 Mo production, namely activation of natural molybdenum using thermal neutron, has been explored. Unfortunately, this neutron-activated 99 Mo has a low specific activity. Therefore, 99 Mo /99m Tc generator based on neutron-activated 99 Mo requires a column with higher capacity absorbent. Thus, in this study, the nanomaterial of alumina (nano- a - Al 2 O 3 ) was synthesized which was expected to have a higher 99 Mo adsorption capacity, so that nano- a - Al 2 O 3 could be potentially used as a matrix of column for 99 Mo/ 99m Tc generator based on neutron-activated 99 Mo. Nano- a - Al 2 O 3 was synthesized by using sol-gel method and characterized using FTIR spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy (TEM). In addition, the Scherrer method was used to determine the size of the crystals. To determine the 99 Mo adsorption capacity of the synthesized nanoalumina, the nano- a -alumina was soaked in nitric acid solution for one hour at room temperature followed by removing the filtrate. Then, the nano- a -alumina was soaked in 99 Mo solution (Na 2 99 MoO 4 ) at certain conditions. The FTIR spectra for nano- a -alumina showed adsorption peak at 450-500 cm -1 which indicated the presence of Al-O bond. The XRD patterns of nanoalumina crystals showed peaks at 2θ region of 25.8°, 35.9°, 38°, 52.8°, and 57.7°, indicating that the synthesized alumina had an α-phase with an average crystal size of ~5.5 nm . The average 99 Mo a dsorption capacity of the synthesized alumina was 47.55 ± 12.3 mg Mo/g nano- a -Al 2 O 3 .

Intermediate oxidation states of technetium in concentrated sulfuric acid solutions

The electrochemical reduction of pertechnetate ions (TcO4−) and properties of such formed reduced Tc containing species (ions and molecules) have been studied in strongly acidic media (4 ÷ 12 M aqueous H2SO4) using electrochemical (cyclic voltammetry (CV); chronoamperometry (CA), chronopotentiometry (CP)) and spectroelectrochemical (UV-VIS OTTLE and Au-SERS) techniques. The results show generation of Tc(V) containing species in the first steps of the pertechnetate electroreduction. The experiments carried out in 6, 8 and 10 M H2SO4 have shown that an increase in the acid concentration shifts the Tc(VII) electroreduction wave towards positive potential values. Additional Au-SERS experiments indicate generation of Tc species with intermediate oxidation states (V) characterised by a band at 792 cm−1 that are distinguishable from TcO2 or polymeric Tc(IV) forms. Application of derivative pulse techniques allows determination of pertechnetates in strongly acidic solutions at a level of 10−6 mol/dm3 even in the presence of impurities, such as Fe3+ and Cl-, with concentrations comparable or greater than pertechnetates.

VALIDATION OF SIMPLE UV-VIS SPECTROPHOTOMETRY METHOD BASED ON ICH Q2 (R1) GUIDELINE FOR THE ANALYSIS OF SODIUM HYPOCHLORITE USING RHODAMINE B

Sodium hypochlorite (NaOCl) has many functions, one of them is as an oxidizing agent in 99 Mo/ 99m Tc generator based on ZBM. However, the NaOCl has cytotoxic effect which can harm human body. Hence, there is a need for analytical procedure for its determination. This study describes the validation parameters given by International Conference on Harmonisation (ICH) Q2(R1) to ensure that the UV-Vis spectrophotometric method using rhodamine B is suitable for determination of NaOCl concentration. This method was validated in respect of linearity, specificity and sensitivity. Whereas, the parameter of accuracy and precision is need to be developed to meet the acceptable criteria. The method resulted in a range of linearity, coefficient of correlation and limit of quantification of 0.2 - 4.8 mg L -1 , 0.996 and 0.2 mg L -1 , respectively.

Preparation and Characterization of Zirconia Nanomaterial as a Molybdenum-99 Adsorbent

The present study deals with the synthesis and characterization of ZrO 2 nanomaterial which can be used as an adsorbent for Molybdenum-99 ( 99 Mo). The adsorbent can potentially be utilized as the material for 99 Mo/ 99m Tc generator column. Using the sol-gel method, monoclinic nanocrystalline zirconia was synthesized from zirconium oxychloride in isopropyl alcohol reacted with ammonium hydroxide solution in isopropyl alcohol resulting in a white gel. The gel was subsequently refluxed for 12 hours at ~95°C and pH at ~4 and then dried at 100°C. The drying gel was then calcined at 600°C for two hours. Meanwhile the orthorhombic nanocrystalline zirconia was obtained by reacting zirconium oxychloride solution with 2.5 M ammonium hydroxide solution which resulted in a white gel. The gel was then refluxed for 24 hours at ~95°C and pH at ~11 and then dried at 100°C. The drying gel was then calcined at 600°C for two hours. These materials were characterized using FT-IR spectroscopy, X-ray diffraction (XRD), and Transmission Electron Microscope (TEM). The Scherrer method is used for determination of crystallite size. The FT-IR spectra for both materials show absorption peak at 450-500 cm -1 which are attributed to Zr-O bond. The XRD pattern of monoclinic nanocrystalline form shows crystalline peaks at 2θ regions of 28.37°, 31.65°, 34°, 36°, and 50.3° with average crystallite size of 2.68 nm. Meanwhile, the XRD pattern of orthorhombic nanocrystalline form shows crystalline peaks at 2θ regions of 30°, 35°, 50°, and 60° with average crystallite size of 0.98 nm. The TEM micrograph indicates that the zirconia nanomaterials prepared were quite uniform in size and shape. Received: 1 2 November 2015; Revised: 9 Septem ber 2016 ; Accepted: 20 September 2016

Development of <sup>99</sup>Mo/<sup>99m</sup>Tc Generator System for Production of Medical Radionuclide <sup>99m</sup>Tc using a Neutron-activated <sup>99</sup>Mo and Zirconium Based Material (ZBM) as its Adsorbent

Molybdenum produced from fission of U-235 is the most desirable precursor for 99 Mo/ 99m Tc generator system as it is non-carrier added and has high specific activity. However, in the last decade there has been short supply of 99 Mo due to several constrains. Therefore, there have been many works performed for development of 99 Mo/ 99m Tc generator system using 99 Mo which is not produced from either LEU or HEU. This report deals with development of 99 Mo/ 99m Tc generator system where zirconium-based material (ZBM) is used as adsorbent of neutron-activated 99 Mo. The system was prepared by firstly irradiating natural Mo in the G. A. Siwabessy reactor to produce neutron-activated 99 Mo. The target was dissolved in NaOH 4N and then neutralized with 12 M HCl. The 99Mo solution was then mixed with a certain amount of ZBM followed by heating at 90°C for three hours to allow the 99Mo adsorbed on ZBM. The 99Mo-ZBM (9.36 GBq of 99 Mo was Mo/ 4.2 g ZBM) was packed on a fritz-glass column. This column was then fitted serially with an alumina column for trapping 99 Mo breakthrough. The columns were then eluted daily with saline solution for up to one week. The yield of 99m Tc was found to be between 53.7 – 74% (n= 5). All 99m Tc eluates were clear solutions with pH of 5. Breakthrough of 99 Mo in 99m Tc eluates was found to be 0.031 ± 0.019 μCi 99 Mo/ mCi 99m Tc (n= 5) which was less than the maximum activity of 99 Mo allowed in 99m Tc solution (< 1 µCi 99 Mo/mCi 99m Tc). Aluminum breakthrough in 99m Tc eluates was found to be less than 10 ppm. The radiochemical purity of 99m Tc in form of Na 99m TcO 4 was > 99%. Radiolabeling of this 99m Tc towards methylene diphosphonate (MDP) kit gave a radiolabelling efficiency of 99%. In summary, a new 99 Mo/ 99m Tc generator system that used neutron-activated 99 Mo and ZBM as its adsorbent has been successfully prepared. The 99m Tc produced from this new 99 Mo/ 99m Tc generator system attained the quality of 99m Tc required for medical purposes. Received: 23 Februari 2016; Revised: 13 July 2016; Accepted: 17 July 2016

Sorption of Mo(VI) on zirconium molybdosilicate gel and potential application as a 99Mo/99m Tc generator

Sorption of Mo(VI) from aqueous nitrate solutions onto zirconium molybdosilicate (ZrMoSi) gel was studied using 99Mo radiotracer. The acid–base titration curve showed that the prepared ZrMoSi gel was an amphoteric material with the point of zero charge (PZC) at pH 2.5. The highest distribution coefficient (600 mL g–1) of 99Mo(VI) on ZrMoSi from nitrate media was achieved at pH 2.1. The sorption kinetics of 99Mo(VI) onto ZrMoSi obeyed the pseudo-second-order model. The breakthrough sorption capacity of ZrMoSi gel was found to be 4.25 × 10–2 [mmol Mo(VI)] g–1. The prepared 99Mo/99mTc chromatographic column generator showed a good performance: The 99mTc elution yield was 87.7%, pH of the eluate ranged from 5.6 to 7.2, and the radionuclidic purity of the eluted 99mTc was >99.99% with a radiochemical purity of 98.31% (as 99mTcO4–).

The Use of Sodium Hypochlorite Solution for (n,γ)<sup>99</sup>Mo/<sup>99m</sup>Tc Generator Based on Zirconium-Based Material (ZBM)

The many problems in preparing fission product 99 Mo led into this work to develop 99 Mo/ 99m Tc generator using neutron-irradiated natural MoO 3 targets and, more specifically, to develop a zirconium-based material (ZBM) for chromatography columns that have an adsorption capacity of more than 100 mg Mo/g ZBM. This paper reports our recent experiments in the use of sodium hypochlorite solution of various concentrations to improve the yield of 99m Tc in performance of (n,γ) 99 Mo/ 99m Tc generators based on the ZBM. The synthesized ZBM was coated with tetraethyl orthosilicate for improving the hardness of the material. The adsorption of [ 99 Mo]molybdate into ZBM was carried out by reacting ZBM into [ 99 Mo]molybdate solution at 90 ° C to form ZBM-[ 99 Mo] molybdate. ZBM-[ 99 Mo]molybdate was then packed into generator column, then eluted with 10 × 1 mL of saline followed by 1 × 5 mL of NaOCl solution. The NaOCl solution concentrations used were 0.5%; 1%; 3%; and 5% for each column, respectively. This study resulted in a ZBM which has a 99 Mo adsorption capacity of 167.5 ± 3.4 mgMo/g ZBM, as well as in a yield eluate of 99m Tc of up to 70%, and the find that the optimum NaOCl concentration was 3%. The use of sodium hypochlorite solution affected 99 Mo breakthrough. The higher sodium hypochlorite concentration used, the more 99 Mo breaktrough exist on 99m Tc eluate. Received: 22 October 2014; Revised: 21 April 2015; Accepted: 21 May 2015

Radioactivity decontamination of materials commonly used as surfaces in general-purpose radioisotope laboratories.

In accord with as-low-as-reasonably-achievable and good-manufacturing-practice concepts, the present study evaluated the efficiency of radioactivity decontamination of materials commonly used in laboratory surfaces and whether solvent spills on these materials affect the findings. Four materials were evaluated: stainless steel, a surface comprising one-third acrylic resin and two-thirds natural minerals, an epoxy cover, and vinyl-based multipurpose flooring. Radioactive material was eluted from a (99)Mo/(99m)Tc generator, and samples of the surfaces were control-contaminated with 37 MBq (100 μL) of this eluate. The same procedure was repeated with samples of surfaces previously treated with 4 solvents: methanol, methyl ethyl ketone, acetone, and ethanol. The wet radioactive contamination was allowed to dry and then was removed with cotton swabs soaked in soapy water. The effectiveness of decontamination was defined as the percentage of activity removed per cotton swab, and the efficacy of decontamination was defined as the total percentage of activity removed, which was obtained by summing the percentages of activity in all the swabs required to complete the decontamination. Decontamination using our protocol was most effective and most efficacious for stainless steel and multipurpose flooring. Moreover, treatment with common organic solvents seemed not to affect the decontamination of these surfaces. Decontamination of the other two materials was less efficient and was interfered with by the organic solvents; there was also great variability in the overall results obtained for these other two materials. In expanding our laboratory, it is possible for us to select those surface materials on which our decontamination protocol works best.