1 / 22

The Determination of 224 Ra, 226 Ra, & 228 Ra in Water Samples

The Determination of 224 Ra, 226 Ra, & 228 Ra in Water Samples. Michael Fern Eichrom Technologies, Inc. Background. EPA monitoring of radium in water in US Ra-224 found in drinking water in New Jersey Need for faster method to measure Ra-224 ASTM + US Geological Survey.

leroya
Download Presentation

The Determination of 224 Ra, 226 Ra, & 228 Ra in Water Samples

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Determination of 224Ra, 226Ra, & 228Ra in Water Samples Michael Fern Eichrom Technologies, Inc.

  2. Background • EPA monitoring of radium in water in US • Ra-224 found in drinking water in New Jersey • Need for faster method to measure Ra-224 • ASTM + US Geological Survey

  3. Original Method – Eichrom RAW01(Burnett, et al., 1995) 1 2 0.5-2 L acidified sample Ba-133 3 Load sample in 0.095M HNO3 1 Ln BaSO4 ppt Rinse 0.095M HNO3 2 0.35M HNO3 3 Resin Conversion to BaCO3 226Ra via Rn emanation 223,224Ra via a-spectrometry 1 2 3 0.095M HNO3 228Ra via 228Ac {proportional or HPGe counter} {hold for ~30 hrs.} g-ray measurement Ba-133

  4. 228Ra Results Burnett, et al. 1995

  5. Limitations of Original Method • α-emitters determined by Rn emanation: too long • Need fast method to measure 224Ra (t1/2 = 3.66 days) • 30 hour ingrowth for 228Ac • Conversion of SO42- to CO32- is tedious

  6. 1 1 2 2 3 3 1 2 3 New Approach - RAW03 Load sample at pH 2 (0.5 – 1 L) Evaporate and re-dissolve in 0.095M HNO3 Rinse 50 mL 0.1M HNO3 50 mL 8M HNO3 1 2 3 Load sample in 0.095M HNO3 Cation 1 Ln Ln Rinse 0.095M HNO3 2 • 0.35M HNO3 3 Resin Resin Resin 224, 226Ra via a-spectrometry 1 2 3 To waste 228Ra via 228Ac {proportional or HPGe counter}

  7. Advantages of New Method • No need for 228Ac ingrowth • Eliminate dangerous and inconsistent carbonate conversion • Rapid measurement of α-emitting isotopes • Same day measurement of 224Ra

  8. 226Ra % Recoveries-0.5L DI Water Eichrom data

  9. 226Ra Alpha Spectrum

  10. 226Ra, 224Ra, and Daughters 224Ra 226 Ra 220Rn 218Po 222Rn

  11. 226Ra % Recoveries in Tap water Eichrom data

  12. 226Ra in EPA SampleSept.18, 1998 Eichrom data

  13. 226Ra in NJ Sample Eichrom data

  14. 226Ra in Georgia Inst. Of Tech. Sample# S8933 Eichrom data

  15. 226Ra in Georgia Inst. Of Tech. Sample# WS 14776 Eichrom data

  16. Sample Chemical recovery (Ba-133) Spiked pCi/L (mBq/L) Found pCi/L (mBq/L) A 92.8% 1.16 (42.9) 1.22 (45.1) B 87.1% 5.80 (215) 5.73 (212) C 84.3% 11.6 (429) 11.7 (433) 226Ra ResultsHerbert, USEPA 2002

  17. Sample Chemical recovery (Ba-133) Spiked pCi/L (mBq/L) Found pCi/L (mBq/L) A 92.8% 32.8 (1210) 32.0 (1180) B 87.1% 10.9 (403) 11.9 (440) C 84.3% 4.37 (162) 4.54 (168) 228Ra ResultsHerbert, USEPA 2002

  18. Ca and Mg Interference in 500 mL Samples Eichrom data

  19. Ca Interference in 100 mL of Sample Eichrom data

  20. Detection Limits – 226RaUS EPA Requires: 37 mBq/L

  21. Summary • <37 mBq/L detection limits achievable • Eliminates inconsistent carbonate conversion • Faster measurement of 224Ra • High amounts of Ca and Mg interferences handled well with 100 mL samples • Acceptable 226Ra and 228Ra recoveries

  22. Special thanks to: • Anil Thakkar, Eichrom Technologies • David McCurdy & Ann Cleveland, ASTM • Dr. B. Parsa, New Jersey department of health, NJDr. B. Kahn, Georgia Institute of Technology, GA • References: • Burnett, W.C., Cable, P.H., & Moser, R.; Determination of Ra-228 in Natural Waters Using Extraction Chromatography, Radioactivity & Radiochemistry, vol. 6, no. 3 (1995) • Herbert, V., USEPA NAREL, Single Operator Test Report, ASTM Test Method: Ra in Water; presented at RRMC, Knoxville, TN 11/2002.

More Related