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


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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.

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

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The determination of 224 ra 226 ra 228 ra in water samples l.jpg

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

Michael Fern

Eichrom Technologies, Inc.


Background l.jpg

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


Slide3 l.jpg

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


228 ra results burnett et al 1995 l.jpg

228Ra Results Burnett, et al. 1995


Limitations of original method l.jpg

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


New approach raw03 l.jpg

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}


Advantages of new method l.jpg

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


226 ra recoveries 0 5l di water l.jpg

226Ra % Recoveries-0.5L DI Water

Eichrom data


226 ra alpha spectrum l.jpg

226Ra Alpha Spectrum


226 ra 224 ra and daughters l.jpg

226Ra, 224Ra, and Daughters

224Ra

226 Ra

220Rn

218Po

222Rn


226 ra recoveries in tap water l.jpg

226Ra % Recoveries in Tap water

Eichrom data


226 ra in epa sample sept 18 1998 l.jpg

226Ra in EPA SampleSept.18, 1998

Eichrom data


226 ra in nj sample l.jpg

226Ra in NJ Sample

Eichrom data


226 ra in georgia inst of tech sample s8933 l.jpg

226Ra in Georgia Inst. Of Tech. Sample# S8933

Eichrom data


226 ra in georgia inst of tech sample ws 14776 l.jpg

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

Eichrom data


226 ra results herbert usepa 2002 l.jpg

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


228 ra results herbert usepa 2002 l.jpg

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


Ca and mg interference in 500 ml samples l.jpg

Ca and Mg Interference in 500 mL Samples

Eichrom data


Ca interference in 100 ml of sample l.jpg

Ca Interference in 100 mL of Sample

Eichrom data


Detection limits 226 ra us epa requires 37 mbq l l.jpg

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


Summary l.jpg

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


Slide22 l.jpg

  • 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.


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