Rapid Separation Methods for Bioassay Samples

S. L. Maxwell, III and D. J. Fauth

Westinghouse Savannah River Site

Advances in Rapid Column Extraction

• Significant advances in last 5 to 10 years

• Broad application in wide range of labs – Advancing analytical technology in process lab, bioassay lab,

environmental lab, etc.

• Sample preparation required for wide range of analytical work – Remove matrix interferences prior to assay

– Preconcentrate analyte

• Advantages – simpler, more selective than ion exchange

– vacuum box speed improvements with cartridge technology

– less waste, lower acidity, less hazardous

Improvements In Column Extraction • 1990’s: Need to upgrade radiochemistry methods at SRS

– Replace solvent extraction methods in CLAB-mixed waste

– Upgrade analytical methods in SRS Bioassay Lab

• Rapid Separation Methods– Process laboratory (liquid and solid samples)

– Bioassay laboratory (urine, fecal)

– Environmental laboratory (soil)

Improvements In Column Extraction • Rapid Column Extraction Applications at SRS

– Process and waste analyses• Pu, Np, U, Am, Th, Sr, Tc-99 for waste and process solutions at SRS

(tandem methods)– E. Philip Horwitz, S.L. Maxwell et al., Analytica Chimica Acta, 310, 63,

(1995).

– S.L. Maxwell III, “Rapid Actinide-Separation Methods”, Radioactivity and Radiochemistry, 8, No 4, 36, (1997)

• UTEVA method for Pu/U oxides (Metal impurities assay on mixed oxide or actinide process solutions to remove U/Pu interferences and characterize materials by ICP-ES and ICP-MS, 1998-1999)

Improvements In Column Extraction

– Process and waste analyses• Trace actinides in mixed oxide materials (Np, Th, Am extraction for

ICP-MS using TEVA, UTEVA-1998-1999)

• Simultaneous extraction of U, Pu for IDMS assay and isotopics in mixed oxides - (2000)

– S.L. Maxwell and J. Satkowski, “Rapid Mass Spectrometry for Uranium and Plutonium”, Radioactivity and Radiochemistry Journal, Vol. 12, No 2, 2001

Recent Column Extraction Applications

• Column Extraction Applications at SRS– Soil and Fecal Sample Analyses

• Actinides in soil using Diphonix Resin-microwave digestion – S.L. Maxwell III and S. Nichols, “Actinide Recovery Method for Large

Soil Samples”, Radioactivity and Radiochemistry, 11, No 4, 46, (2000)

• Pu, Am in fecal samples using Diphonix Resin-microwave digestion and TEVA+TRU Resin, (1999)

– S.L. Maxwell and D. Fauth, “New Fecal Method for Pu and Am”, Journal of Radioanalytical and Nuclear Chemistry, Vol. 250, No. 1 , 2001

Recent Column Extraction Applications

• Column Extraction Applications at SRS, contd.

– Bioassay: urine• Column extraction in Bioassay Lab for Pu, Np, Am, U plus Sr method

using cartridge technology – S.L. Maxwell III and D. Fauth, “Rapid Column Extraction Methods for Urine”,

Radioactivity and Radiochemistry, 11, No 3, 28, (2000)

Bioassay Urine Methods

• Improve chemical recoveries, improve Th-228 removal and reduce labor costs/rework– Pu (+Np when Pu-236 tracer used) on TEVA Resin

– Pu, Np, U, Am, Sr • Single two cartridge TEVA/TRU column plus SR Resin

• No iron in urine allows novel, stacked TEVA+TRU column

• Pu, Np on TEVA; U, Am on TRU cartridge in stacked column

• Sr collected, evaporated, redissolved, separated on SR Resin column

Urine Batch: Calcium Phosphate Precipitation

Pu, Np/Am, U, Sr on TEVA/TRU RESIN (URINE)

Rinse20 mL 3MHN03

Th Removal3mL 9MHCI/30mL

8MHCI

Pu Elution30mL

0.10MHC1 - 0.05MHF - 0.1M NH4l

1) Adjust to 2.5MHN03 - 1M Al(NO3)3

2) 0.05M Sulfamic Acid + 0.2M Ascorbic Acid3) 0.4 to 0.5M Sodium Nitrite

Remove TRU cartridge:1) Elute Am with

12mL 4M HCI2) Elute U with

20mL 0.1M ammoniumbioxalate

2mL TEVA Resin(50-100 um)

2.0mL TRU-Resin(50-100 um)

Collect, evaporate, dissolve in 6M HNO3SR Resin

Electrodeposition

4mls 0.02M H2SO4 + 3mls 16M HN03

Evaporate/ash

TEVA+ TRU Stacked Column: Pu, Np, U, Am

TRU Cartridge: U, Am Stripping

SR Cartridge: Sr-90 Separation

TEVA Pu Tracer Recoveries

500 mL urine sample/ Pu-242 tracer= 1.25 dpm / One TEVA Column Fe+AA/+NO2

%Recovery (CeF3 microprecipitation) % Recovery (Electroplating* )

1) 110 1) 84.4

2) 93.3 2) 72.4

3) 92.6 3) 69.3

4) 95.2 4) 69.6

5) 101.5 5) 79.8

6) 99.3 6) 84.5

7) 97.7 7) 79.1

8) 115.4 8) 85.5

9) 107.9 9) 84.8

10) 106.8 10) 77.0

11) 101.6 11) 82.5

12) 102.6

Avg. = 102.0% (7.0% @1s) Avg. = 79.0 (6.2% @1s)

*Add 4 mL 0.02M H2SO4 to enhance F removal during solution cleanup for plating

TEVA- Np-237 , Pu-236 Recoveries

500 mL urine sample/ Np-237 spike= 1.40 dpm/Pu-236=0.425 dpm

Single TEVA column (CeF3 microprecipitation)

% Pu-236 % Np-237

Recovery Recovery

1) 94.0 ***

2) 92.5 ***

3) 101 ***

4) 100 ***

5) 111 ***

6) 91.0 88.1

7) 91.9 86.7

8) 105 102.9

9) 109 102.0

10) 88.9 94.2

Avg. =98.4% (7.9% @1s) Avg. = 94.8% (7.6% @1s)

Additional bias comparison on 24 samples: -1.49% +/- 6% estimate of bias

Bioassay Lab Alpha Counters

Bioassay Lab Gas Proportional Counters:Sr

%bias Np Control Samples

-80%

-60%

-40%

-20%

0%

20%

40%

60%

80%Bias = -2.5% RSD = 11.0 June 2000 - January 20023067 samples

TRU Resin -Am Tracer Recoveries

500 mL urine sample/ Am-243 tracer= 1.55 dpm / TRU cartridge after TEVA SA+AA/+NO2 / load TEVA and TRU at same time/remove TRU cart./elute Am

% Am-243 Recovery (Electroplating)1) 93.2

2) 92.1

3) 107.4

4) 70.3

5) 102.4

6) 103.0

7) 100.2

8) 103.3

9) 102.6

10) 94.7

Avg. = 96.9% (10.6% @1s)

Recent Advances In Urine Method

• Use scrubbed U-232 tracer to minimize Th-228 daughter added and eliminate need for 2nd TEVA column cleanup when uranium analyzed with Pu, Np, Am, Sr

• Add boric acid to eliminate adverse effect of trace fluoride on electroplating/increased tracer recoveries

Th-228 In-Growth After Removal from U-232

Microwave Digestion of Diphonix: Fecal Method

2

Pu on TEVA RESIN(2nd Column to Remove all Th-228)

• Redissolve in 7.5mL 3M HN03 + 1mL 2.5M Al(NO3)3

• Add 0.5mL 1.5M Ferrous Sulfate + 1mL 1.5M Ascorbic Acid• Add 1mL 3.5M Sodium Nitrite• Add 1mL 16M Nitric Acid

Th Removal3mL 9MHCI/7mL

8MHCIRinse

10mL 3MHN03

Pu Elution20 mL

0.10MHC1 - 0.05MHF - 0.1M NH4l

1mL TEVA Resin

% Bias Plot for DOELAP Proficiency Test

-40.0

-20.0

0.0

20.0

40.0

60.0

Pu-238 Pu-239 /240 U-234 U-238 Np-237 Am-241 Sr-90

% B

ias

Urine %Bias Fecal %Bias Acceptable Lower % Acceptable Upper %

% RSD Plot for DOELAP Proficiency Test

0.0

10.0

20.0

30.0

40.0

50.0

Pu-238 Pu-239 /240 U-234 U-238 Np-237 Am-241 Sr-90

% RS

D

Urine %Bias Fecal %Bias Acceptable Upper % Acceptable Upper %

Summary

• New rapid column extraction methods have greatly improved radiochemical separation technology– process lab support

– bioassay lab applications

– environmental lab work

• Vacuum-enhanced column and cartridge extraction methods have enhanced lab capabilities– simpler, faster, less rework, less waste

• Rapid extraction technology continues to advance at the frontier of radioanalytical chemistry