Separation of no-carrier-added rhenium from bulk tantalum by the sodium malonate–PEG aqueous biphasic system

The aqueous biphasic system (ABS) involving sodium malonate–polyethylene glycol (PEG) phases has been applied for the first time for separation of no-carrier-added ¹⁸³Re (T_1/2=70 d) from α-particle irradiated bulk tantalum target. The various ABS conditions were applied for investigating the separation by varying pH, temperature, PEG-molecular weight, concentration of salt. The extraction pattern was hardly affected by change in pH and the molecular weight of PEG. One step separation of nca ¹⁸³Re from Ta was achieved at the optimal conditions of (i) 50% (w/w) PEG-4000—2 M sodium malonate, 40 °C and (ii) 50% (w/w) PEG-4000—3 M sodium malonate, room temperature (27 °C).     

间[*I]苄胍的合成

放射性的间碘苄胍在临床上被广泛用于神经内分泌瘤的诊断和治疗。相比于有载体方法合成的[*I]MIBG,无载体方法合成的[*I]MIBG已经被证实了更有效且副作用更小。现合成了一种无载体MIBG的锡前体——间位三丁基锡基苄胍,经试验标记率为85%以上。     

Chelating ion-exchange methods for the preparation of no-carrier-added Cu

IntroductionWe have developed a method for producing no-carrier-added ⁶⁴Cu by using chelating resin bearing iminodiacetic acid groups.MethodsWe optimized the conditions for the selective separation of radioactive Cu from Ni and Co using the chelating resin and produced no-carrier-added ⁶⁴Cu under the optimized conditions. We analyzed the amounts of the metal ions present in ⁶⁴Cu by inductively coupled-plasma mass spectroscopy (ICP-MS) and optical emission spectroscopy (ICP-OES), and performed radiolabeling of monoclonal antibodies in order to investigate the quality of the ⁶⁴Cu produced in this study.ResultsRadioactive Cu was separated from Ni and Co with 0.1 and 2 M HCl solutions. The yield of ⁶⁴Cu isolated from the ⁶⁴NiO target was almost 87%. The radiochemical purity of ⁶⁴Cu obtained from different amounts of ⁶⁴NiO targets was >99% in all cases. We found that the ⁶⁴Cu solution presented extremely low amounts of the metal ions and showed high specific activity (average: 595 GBq/μmol). Moreover, the antibodies were labeled with ⁶⁴Cu with a high average efficiency (average: 88%).ConclusionsWe could efficiently separate ⁶⁴Cu by using short ion-exchange columns. The chelating ion-exchange method provides a high quality of ⁶⁴Cu that is sufficient for the synthesis of ⁶⁴Cu-labeled antibodies and medical applications.     

Incorporation of thiosemicarbazide in Amberlite IRC-50 for separation of astatine from α-irradiated bismuth oxide

A chelating resin was synthesized by incorporating thiosemicarbazide into Amberlite IRC-50, a weakly acidic polymer. Astatine radionuclides produced by alpha-irradiating bismuth oxide were separated using the newly synthesized chelating resin. The resin showed high selectivity for astatine. The adsorbed astatine was recovered using 0.1M EDTA at pH approximately 10.     

A simple and rapid technique for radiochemical separation of iodine radionuclides from irradiated tellurium using an activated charcoal column

A simple and inexpensive method for the separation of medically useful no-carrier-added (nca) iodine radionuclides from bulk amounts of irradiated tellurium dioxide (TeO₂) target was developed. The β⁻ emitting ¹³¹I radionuclide, produced by the decay of ¹³¹Te through the ^natTe(n, γ)¹³¹Te nuclear reaction, was used for standardization of the radiochemical separation procedure. The radiochemical separation was performed by precipitation followed by column (activated charcoal) chromatography. Quantitative post-irradiation recovery of the TeO₂ target material (98–99%), in a form suitable for reuse in future irradiations, was achieved. The overall radiochemical yield for the complete separation of ¹³¹I was 75–85% (n=8). The separated nca ¹³¹I was of high, 99%, radionuclidic and radiochemical purities and did not contain detectable amounts of the target material. This method can be adopted for the radiochemical separation of other different iodine radionuclides produced from tellurium matrices through cyclotron as well as reactor irradiation.     

Clinical evaluation of no-carrier-added meta-[123I]iodobenzylguanidine for myocardial scintigraphy

In clinical and research studies, images obtained using carrier-added meta-[¹²³I]iodobenzylguanidine (c.a. [¹²³I]MIBG) have shown quite variable quality, with varying levels of uptake in lung, liver and mediastinum; this is a significant problem for quantification of the myocardial uptake by means of region ratios. First experimental and preliminary human data in respect of no-carrier-added (n.c.a.) [¹²³I]MIBG are indicative of improved imaging quality. The aim of the present study was to evaluate the clinical value of myocardial scintigraphy with n.c.a. [¹²³I]MIBG in patients with tachyarrhythmias. The study population comprised 24 patients with tachyarrhythmogenic diseases routinely studied by cardiac single-photon emission tomography (SPET) with [¹²³I]MIBG. Twelve of the 24 patients were studied with c.a. [¹²³I]MIBG (seven females and five males; mean age 42±13 years, range 20–60 years), whereas the other 12 were studied with n.c.a. [¹²³I]MIBG (ten females, two males; mean age 41±11 years, range 18–60 years, P=NS). For quantification of the specific uptake in the different organs, count ratios were calculated on SPET images acquired 4 h p.i. Visual analysis of all [¹²³I]MIBG scans showed improved image quality (improved contrast between heart and neighbouring organs) in n.c.a. studies as compared with c.a. studies. A significantly higher heart/left atrial blood ratio was found in the n.c.a. studies as compared with the c.a. studies (10.3±3.2 vs 5.3±1.3, P=0.0003); furthermore, significantly higher heart/lung and heart/liver ratios (2.5±0.6 vs 1.5±0.3, P=0.0002, and 0.8±0.2 vs 0.6±0.1, P=0.0006, respectively) were obtained in the c.a. studies, whereas lung/left atrial blood and liver/left atrial blood ratios showed no significant differences (4.2±1.3 vs 3.6±1.1, P=0.39, and 13.7±5.2 vs 9.6±2.2, P=0.21, respectively). In conclusion, the use of n.c.a. [¹²³I]MIBG yields a significantly higher myocardial uptake associated with improvement in contrast between the heart and neighbouring organs and is therefore superior to the commercially available c.a. [¹²³I]MIBG for use in clinical and research studies of the myocardial presynaptic sympathetic nervous system. Furthermore, our data indicate that for quantification the use of a left atrial blood reference region of interest, which is only available on SPET studies, is to be recommended. Received 22 September and in revised form 2 November 1999     

无载体131I-MIBG锡试剂前体的合成

目的：探讨合成制备一种无载体131I-MIBG的前体化合物。方法：从简单原料间碘苄胺开始,通过3步反应合成无载体131I-MIBG的锡试剂前体N,N＇-二（叔丁氧羰基）-3-（三丁基锡基）-苄胍,用同位素131I标记制备无载体131I-MIBG,测定其标记率。结果：总收率41.5%,经红外光谱、核磁共振谱、质谱进行结构确证,制备的无载体131I-MIBG标记率大于80%。结论：合成了一种合适的锡试剂前体,可以用于制备无载体131I-MIBG。该合成路线收率高,原料易得,反应条件温和,操作简单,适合实验室条件下制备。