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REVIEW ARTICLE
Year : 2013  |  Volume : 36  |  Issue : 4  |  Page : 193-195  

Sequential separation of uranium, americium and plutonium from urine by extraction chromatography


1 Health Physics Laboratory, Health Physics Unit, Health Physics Division, Bhabha Atomic Research Centre, Kalpakkam, Tamil Nadu, India
2 Health Physics Division, Bhabha Atomic Research Centre, Mumbai, Maharashtra, India

Date of Web Publication8-Oct-2014

Correspondence Address:
N Praveena
Health Physics Laboratory, Health Physics Division, Bhabha Atomic Research Centre, Kalpakkam, Tamil Nadu
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0972-0464.142384

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  Abstract 

A rapid method for sequential separation of uranium, americium and plutonium from urine samples by extraction chromatography was developed. In this method, U-TEVA and TRU-resin columns were used for the separation of the radionuclides. By this method U, Am and Pu could be separated from urine samples with high recoveries and no interference from the sample matrix was observed. Radiochemical recoveries observed in the study were in the range 63.8-100%. Column separation of the radionuclides could be completed within 3 h compared to the present practice of separation of these radionuclides by ion exchange method which requires minimum 3 days to complete the separation.

Keywords: Am, extraction chromatography, Pu, U, urine


How to cite this article:
Praveena N, Santhanakrishnan V, Sankaran M R, Purohit R G, Tripathi R M. Sequential separation of uranium, americium and plutonium from urine by extraction chromatography. Radiat Prot Environ 2013;36:193-5

How to cite this URL:
Praveena N, Santhanakrishnan V, Sankaran M R, Purohit R G, Tripathi R M. Sequential separation of uranium, americium and plutonium from urine by extraction chromatography. Radiat Prot Environ [serial online] 2013 [cited 2019 Nov 13];36:193-5. Available from: http://www.rpe.org.in/text.asp?2013/36/4/193/142384


  Introduction Top


The in-vitro monitoring of the radiation workers handling actinides is done by analysis of urine samples submitted by them. The radionuclides U, Am and Pu being alpha emitters need to be separated from bulk samples and deposited as a thin source before they can be estimated by alpha spectrometry. At present, these radionuclides are separated using ion exchange methods which require minimum 3 days to complete the separation. Extraction Chromatography method using U-TEVA and TRU-resins is highly efficient in separation of actinides from biological samples. In this study, stacked U-TEVA and TRU-resin columns were used for rapid separation of U, Am, and Pu from the urine sample. The radionuclides after separation were deposited as a thin source on stainless steel planchets and the activities were estimated by alpha spectrometry.


  Experimental Top


Reagents

U-TEVA resin (di-pentylpentylphosphonate) and TRU-resin (tri-n-butylphosphate and N, N-di-isobutylcarbamoylmethylphosphine oxide) were used in this study. U-TEVA resin is selective for uranium while TRU-resin is selective for Am and Pu. All other reagents like HNO 3 , HCl used were of ACS grade. Radiochemical tracers obtained from BARC, Mumbai and diluted to the required activity of 232 U - 10.85 mBq/ml, 243 Am - 4.596 mBq/ml and 242 Pu - 8.22 mBq/ml were used.

Procedure

Column preparation


Resin columns of bed volume 2 ml were prepared by transferring 1 g of each of U-TEVA and TRU-resins in water slurry to glass columns. Flow rates of these columns were maintained at 1-2 mL/min.

Standardization of the procedure

The procedure was standardized by analyzing 10 samples spiked with 232 U, 243 Am, and 242 Pu tracers. For this purpose, 100 mg Ca, 1 ml each of 232 U, 243 Am, and 242 Pu tracers were added to 50 ml glass beaker and evaporated to dryness. The residue was dissolved in 5 ml of 3M HNO 3 +1M Al 2 (NO 3 ) 3 and taken up for column separation.

Sample preparation

Urine samples collected from non-radiation workers of volume 1200 ml were wet-ashed using concentrated HNO 3 and H 2 O 2 after addition of radiotracers 232 U, 243 Am, 242 Pu, and 100 mg Calcium carrier. Pre-concentration of radionuclides was carried out by calcium carrier co-precipitation at pH 9 by adding 1:1 Ammonia solution. Precipitate was allowed to settle overnight, centrifuged, dissolved in concentrated HNO 3 , and evaporated to dryness. The white residue was dissolved in 5 ml of 3M HNO 3 +1M Al 2 (NO 3 ) 3 . Valence adjustment was carried out by addition of 1 ml of 1.5M Sulfamic acid and 1 ml of 1.5M Ascorbic acid to reduce Pu +4 to Pu +3 so that it is retained in the TRU column and to reduce trivalent Fe which will interfere in the retention of Am in the TRU column. [1]

Column separation

The column separation procedure is based on stacked column procedure outlined in Eichrom Analytical Procedures [2] and by Thakkar. [3] In this method, U-TEVA column was stacked over TRU column and the sample solution was loaded in the stacked column after conditioning with 10 ml of 3M HNO 3 . The columns were separated after beaker rinse and column wash with 10 ml of 3M HNO 3 .

Uranium

U-TEVA column was washed with 5 ml of 9M HCl and 20 ml of 5M HCl + 0.05M Oxalic acid and uranium was eluted with 15 ml of 1M HCl.

Americium and plutonium

TRU column was washed using the following solutions sequentially; 5 ml of 2M HNO 3 , 5 ml of 2M HNO 3 + 0.1M NaNO 2 , 5 ml of 0.5M HNO 3 . Americium was eluted with 3 ml of 9M HCL and 20 ml of 4M HCl. Thorium removal was carried out by 25 ml of 4M HCl+0.1M HF, and plutonium was eluted with 10 ml of 0.1M ammonium bioxalate. Flowchart of the column separation procedure is given in [Figure 1].
Figure 1: Flow chart for sample preparation and column separation

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Source preparation

The eluted solutions were evaporated to dryness, and the radionuclides were electro-deposited as a thin source on SS planchets in (NH 4 ) 2 SO 4 medium at pH 2.2. The radionuclide activities were estimated by alpha spectrometry.


  Results and discussion Top


In the procedure, standardization study, radiochemical recoveries of 80-100% could be achieved for all the three radionuclides. This standardized procedure was adopted for separation from urine samples.

In this study, 18 urine samples were analyzed, and the radiochemical recoveries obtained are given in the [Table 1].
Table 1: Chemical recovery of radionuclides


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The resins used were found to be highly selective, and the separations free from interferences (thorium and 210 Po) could be achieved. The radiochemical recoveries of U and Pu are comparable with the conventional ion exchange method and Am recoveries obtained are considerably better in comparison. Reproducibility of this method was confirmed by consistent recoveries obtained for the radionuclides analyzed. Column separation of the radionuclides could be completed within three hours compared to minimum three days required for conventional ion exchange method resulting in a significant reduction in analysis time and increase in the number of samples that can be analyzed.

American National Standards Institute N13.30 [4] defines the acceptance criterion for radiobioassay as-25 to+50% for relative bias and 40% for relative precision, respectively. The overall relative bias for uranium, americium, and plutonium was found to be-22%, −20% and-17%, respectively. Reproducibility of the radiochemical recoveries was calculated using relative precision and was found to be 16%, 23%, and 10% for uranium, americium, and plutonium, respectively.


  Conclusion Top


Stacked U-TEVA and TRU columns used for sequential separation of U, Am, and Pu present in the urine samples were found to highly efficient, reliable, and rapid. Recoveries obtained by this method are comparable with the ion exchange method for U and Pu and considerably better for Am. This method could be used in the analysis of urine samples in emergency situations as well as in routine analyses.

 
  References Top

1.Maxwel SL 3 rd . Rapid analysis of emergency urine and water samples. J Radioanal Nucl Chem 2008;275:497-502.  Back to cited text no. 1
    
2.Americium, Plutonium and Uranium in Urine. ACUO2, Analytical Procedures Rev. 1.6; Eichrom Technologies 2005.  Back to cited text no. 2
    
3.Thakkar AH. A rapid sequential separation of actinides using Eichrom's extraction chromatographic material. J Radioanal Nucl Chem 2002;252:215-8.  Back to cited text no. 3
    
4.Performance Criteria of Radio-Bioassay: Health Physics Society. American National Standards Institute ANSI N13.30-2011  Back to cited text no. 4
    


    Figures

  [Figure 1]
 
 
    Tables

  [Table 1]


This article has been cited by
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Zhongtang Wang,Jian Zheng,Keiko Tagami,Shigeo Uchida
Journal of Radioanalytical and Nuclear Chemistry. 2017;
[Pubmed] | [DOI]



 

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