[en] Radiochemical separations have traditionally been performed by various techniques which could be classified into one of three general classes of chemical separations. They are: precipitation separations, liquid-liquid separations, and ion-exchange separations. To differing degrees all of the above suffer from various issues that make their inclusion as part of modern radiochemical laboratory methodology problematic. The two main issues are that the techniques are typically time consuming and they tend to generate relatively large quantities of waste in an era when waste minimization is being vigorously pursued. A relatively new type of separation technique has been used in the past five years that is both more timely in its use and lends itself to the pursuit of minimum waste volumes in the laboratory. That technique is extraction chromatography. Here, the selectivity of solvent extraction is combined with the simplicity of column chromatography. Incorporation of selective solvents such as crown ethers allows the radiochemist to perform separations rapidly with minimum waste volumes generated for disposal by the laboratory. Examples of extraction chromatography using crown ethers will be discussed

[en] The concentrations of transuranic elements in the environment are usually extremely low. Special procedures are needed for preconcentration and separation of these nuclides from various matrices and from other actinides. Traditional ion exchange methods have been used for separation of Pu and Am for decades. In recent years extraction chromatography methods based on new materials have been developed. These new methods are simpler and faster to use than the conventional methods based on ion exchange, especially for americium. In this work application of Eichrom's extraction chromatography resins (UTEVA, TRU, TEVA) and an anion exchange resin (Dowex lx4) were studied for the separation of Pu and Am from different natural matrices. (au)

[en] The Radiochemical Engineering Development Center at Oak Ridge National Laboratory processes irradiated targets to recover the transplutonium actinides for research and industrial users. In a typical processing campaign, dekagram quantities of curium are recovered for recycle into targets for subsequent irradiation and processing; decigram quantities of californium are recovered for fabrication into neutron sources; and milligram quantities of einsteinium and berkelium as well as picogram quantities of fermium are recovered for distribution to the research community. The transcurium actinides are separated in a series of chromatographic elutions using a cation-exchange resin and ammonium α-hydroxyisobutyrate as the eluant. The fermium fraction from these final purification runs still contains significant amounts of rare earth fission products, such as yttrium, dysprosium, and holmium. In the most recent campaign, a process using a TEVA trademark resin extraction chromatography column was developed and tested to determine its effectiveness in providing a fermium product free of rare earth fission products. Gamma spectroscopy indicated that dysprosium and holmium were reduced to levels less than minimum detectable limits and that only 0.07 pg of ⁹¹Y remained in the final fermium product, which contained 0.5 pg of ²⁵⁷Fm. An overall decontamination factor of ∼10³ was achieved for fission product removal

No abstract available

No abstract available

[en] Extraction chromatographic studies of XAD-7 impregnated with unsymmetrical phosphonate, Dibutylamyl phosphonate (DBAP) for the extraction of uranium and thorium were carried out. The present studies indicate that uranium and thorium in 4 M HNO₃ were successively loaded and eluted with 0.01 M nitric acid. (author)

[en] In order to enrich ¹⁰B, 40 meter band migration of boric acid-mannitol with hydrochloric acid solution was performed by inverse frontal chromatography on a porous, 25% crosslinked, 38% quaternized 4-vinylpyridine-divinylbenzene resin. The maximum enrichment (R_L) of ¹⁰B was 94.15%. The overall process parameters, namely slope coefficient (k) and separation coefficient (e), were found to be 0.1282 cm^-1 and 0.02967, respectively

[en] Neptunium and uranium behavior in extraction chromatography system, aiming the separation of microquantities of neptunium from uranyl nitrate solutions is described. Tri-n-octylamina (TOA), tri-n-butylphosphate (TBP), thenoyltrifluoroacetone (TTA) as stationary phase, alumina, Voltalef-UF-300, silica as support material were verified. The impregnation conditions as well as the best stationary phase/support material ratio were established. TBP/alumina, TBP/Voltalef and TOA/alumina system were selected to uranium and neptunium separation studies. In the system using TBP as extractant agent uranium and neptunium separation was reached by selective elution after the retention of both elements on the column. U-Np separation by selective retention of Np was possible with TOA system. The capacity of the column was the 66.6 mg U/mL and 191.6mg U/mL for the TBP/alumina and TBP/Voltalef systems, respectively. An application of extraction chromatography system in the final phase of irradiated uranium treatment process is proposed. (author)

[en] 1-H-1-(3-[¹⁸F]fluoro-2-hydroxypropyl)-2-nitroimidazole ([¹⁸F]FMISO), is the most used hypoxia-imaging agent in oncology and we have recently reported a fully automated procedure for its synthesis using the Nuclear Interface FDG module and a single neutral alumina column for purification. Using 1-(2'-nitro-1'-imidazolyl)-2-O-tetra-hydropyranyl-3-O- toluenesulfonylpropanediol (NITTP) as the precursor, we have investigated the yield of [¹⁸F]FMISO using different reaction times, temperatures, and the amount of precursor. The overall yield was 48.4 ± 1.2% (n = 3), (without decay correction) obtained using 10 mg NITTP with the radio-fluorination carried out at 145 deg C for 3 min followed by acid hydrolysis for 3 min at 125 deg C in a total synthesis time of 32 ± 1 min. Increasing the precursor amount to 25 mg did not improve the overall yield under identical reaction conditions, with the decay uncorrected yield being 46.8 ± 1.6% (n = 3), but rather made the production less economical. It was also observed that the yield increased linearly with the amount of NITTP used, from 2.5 to 10 mg and plateaued from 10 to 25 mg. Radio-fluorination efficiency at four different conditions was also compared. It was also observed by radio thin layer chromatography (radio-TLC) that the duration of radio-fluorination of NITTP, not the radio-fluorination temperature favoured the formation of labeled thermally degraded product, but the single neutral alumina column purification was sufficient enough to obtain [¹⁸F]FMISO devoid of any radiochemical as well as cold impurities. (author)

[en] Published in summary form only