Year : 2011 | Volume
: 34 | Issue : 3 | Page : 157--158
Radioanalytical determination of plutonium and americium using ion exchange and extraction chromatography technique in urine
V Santhanakrishnan1, KR Sreedevi1, S Rajaram1, PM Ravi2,
1 Environmental Survey Laboratory, Environmental Studies Section,Health Physics Division, BARC, Kalpakkam, Tamil Nadu, India
2 Environmental Studies Section, Health Physics Division, BARC, Mumbai, India
Environmental Survey Laboratory, Environmental Studies Section,Health Physics Division, BARC, Kalpakkam, Tamil Nadu
The use of anion exchange chromatography for the separation of Pu and extraction chromatography technique for the separation of Am from urine samples was studied. In the earlier method, Pu separation was carried out by anion exchange chromatography followed by Am separation by cation exchange chromatography. The chemical recovery of Am obtained by cation exchange separation method was inconsistent and low in the range 30-70%. In this study, the average Pu recovery obtained using anion exchange chromatography was 89.2 with standard deviation of 10.4 and the average Am recovery obtained using extraction chromatography with TRU resin was 77.4 with standard deviation of 14.8. Moreover, Am separation could be completed within three hours using the TRU column compared to two days that were required for the cation exchange chromatography.
|How to cite this article:|
Santhanakrishnan V, Sreedevi K R, Rajaram S, Ravi P M. Radioanalytical determination of plutonium and americium using ion exchange and extraction chromatography technique in urine.Radiat Prot Environ 2011;34:157-158
|How to cite this URL:|
Santhanakrishnan V, Sreedevi K R, Rajaram S, Ravi P M. Radioanalytical determination of plutonium and americium using ion exchange and extraction chromatography technique in urine. Radiat Prot Environ [serial online] 2011 [cited 2021 Jan 20 ];34:157-158
Available from: https://www.rpe.org.in/text.asp?2011/34/3/157/101682
Plutonium and Americium being alpha emitters need to be separated from biological samples like urine and deposited as a thin source on a stainless steel disc, so that the activities can be estimated by alpha spectrometry at very low levels. From urine samples, Pu after pre-concentration is separated by anion exchange column. This method is well established and the chemical recoveries obtained are high and consistent. Am separation is carried out by preconcentration with bismuth phosphate/calcium oxalate precipitation followed by radiochemical separation using cation exchange chromatography. The chemical recovery obtained using this method was inconsistent and low in the range 30-70%. Extraction chromatography technique using resins, which are element selective, have been found to be highly efficient in the separation of transuranics from different types of biological samples. In this study, anion exchange separation method was used for separation of Pu and extraction chromatography technique using TRU resin, which contains N,N-di-isobutyl carbamoyl methyl phosphine oxide (CMPO) as extractant and tri-n-butyl phosphate (TBP) as diluent adsorbed on inert polymeric support, has been used for the separation of Am from urine.
2. Materials and Methods
Urine sample of volume 1200 ml was wet ashed with 40 ml HNO 3 and 10 ml H 2 O 2 for six hours after adding 1 ml of 100 mg/ml Ca carrier as Ca(NO 3 ) 2 . 236 Pu and 243 Am tracers were also added in order to determine the radiochemical yields. The oxidation state of Pu in the sample was reduced to +3 with the addition of 100 mg NH 2 OH.HCl and the sample was allowed to cool down. Pu and Am in the sample were co-precipitated along with calcium phosphate with addition of 1:1 ammonia solution at pH 9 and allowed to settle overnight. After decanting the supernatant the precipitate was centrifuged, dissolved in HNO 3 and evaporated to dryness.
2.1 Pu separation
The residue was dissolved in 5 ml 8M HNO 3 and the separation was carried out as per the procedure given in the ERL Procedure Manual (ERL Procedure Manual,1998).  Briefly, the Pu in the sample solution was converted to Pu +4 with the addition of 1 ml of 1M NaNO 2 . The sample solution was loaded on DOWEX 1X8 anion exchange resin column (dia −0.8 cm, height -7.0 cm) pre-conditioned with 40 ml 8M HNO 3 . The column was washed with 50 ml 8M HNO 3 to remove the sample matrix components, Am and U. The 8M HNO 3 effluent was preserved for Am separation. Th was removed from the column by washing with 40 ml 8M HCl and was discarded. Pu from the column was eluted with 50 ml 1.5M NH 2 OH.HCl and evaporated to dryness. The hydroxylamine residue was decomposed with HNO 3 and Pu was electro-deposited on a SS planchet in NH 4 (SO 4 ) 2 solution at pH 2.2 for two hours. The Pu activity in the planchet was estimated using Alpha Spectrometry system consisting of 450 mm 2 PIPS (Passivated Implanted Planar Silicon) detectors with a resolution of 28 keV and efficiency of 24%. Chemical recovery was determined from the activity of 236 Pu tracer.
2.2 Am separation
This method is based on the determination of actinides in urine and water samples by extraction chromatographic method outlined by Arginelli et al., Maxwell and Thakkar (Arginelli, 2005 and 2008; Maxwell, 2008; and Thakkar, 2002) ,,, in which TRU-resin was used to separate Am. The 8M HNO 3 effluent from the Pu separation step was dried and the residue was dissolved in 10 ml 3M HNO 3 -1M Al(NO 3 ) 3 and was loaded on a TRU resin column (dia −0.35 cm, height -5 cm) pre-conditioned with 10 ml 3M HNO 3 . The column was rinsed with 5 ml 3M HNO 3 and 5 ml 2M HNO 3. The nitrate concentration was lowered with addition of 5 ml 0.5M HNO 3 . Am was eluted from the column with 3 ml 9M HCl and 20 ml 4M HCl. The eluate was dried and the electro-deposition and estimation of Am activity in the sample was done by the same method used for Pu. Chemical recovery was determined from the activity of 243 Am tracer.
3. Results and Discussion
In this study, 21 urine samples were analyzed. The recovery of Pu varied between 70 and 100 with a mean of 89.2 and standard deviation of 10.4. The Am recovery was in the range of 66-96 with a mean of 77.4 and standard deviation of 14.8. The TRU resin was observed to be highly selective for Am and there was no interference from 210 Po which is normally present in urine samples. The TRU column could be used for ten samples after which the recovery of Am falls below 50% and had to be replaced. The Am separation with TRU column could be completed within three hours compared to two days that were required with the cation exchange separation method. Moreover, the quantity of reagents used was also small resulting lower generation of reagent waste.
Extraction chromatography technique was found to be highly efficient in the separation of Am from urine. The procedure used for radiochemical separation of Pu by anion exchange chromatography followed by Am separation by extraction chromatography using TRU resin from urine gave consistently good recoveries. The time taken to complete Am separation by extraction chromatography technique was less than three hours.
The authors express their sincere gratitude to Dr. A. K. Ghosh, Director, HS&E Group, BARC, Dr. D. N. Sharma, Associate Director, HS&E Group, BARC, and Dr. P. K. Sarkar, Head, Health Physics Division, BARC for their keen interest in the work.
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