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The Determination Of 226 Ra In Soil Samples Lawrence D. Morris General Engineering Laboratories, Inc. Anil H. Thakkar Eichrom Technologies, Inc.
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General Engineering Laboratories, Inc. Charleston, SC Objective: Design a reliable method to measure 226 Ra in soil samples by Alpha Spectroscopy thus meeting the current need of our clients. Faster Turn Around Times than current methods This procedure utilizes Cation and Eichrom’s Ln Resin Achieve Peak Resolution (FWHM) of less than 100keV
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General Engineering Laboratories, Inc. Charleston, SC Anil Thakkar visited GEL in April Discussed the Radium in Water procedure –Ran some test samples
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General Engineering Laboratories, Inc. Charleston, SC Spectrum from Testing Water Procedure
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General Engineering Laboratories, Inc. Charleston, SC This brought up the question about how well the procedure would work with soils? Spectrum from Testing Water Procedure
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General Engineering Laboratories, Inc. Charleston, SC Highlights of the Procedure: Radium in Water (RAW03) Eichrom Technologies, Inc. Digest the sample Dissolve the residue with dilute HNO 3 Pass sample through Cation resin column Elute Ra and Ba with 8M HNO 3 Evaporate eluate to dryness Dissolve residue with 0.095M HNO 3
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General Engineering Laboratories, Inc. Charleston, SC Pass through Ln Column collecting the eluate for determination of 226 Ra Perform Barium Sulfate micro-precipitation Filter Count on Gamma for Tracer Recovery ( 133 Ba) Count on Alpha for 226 Ra determination Highlights of the Procedure: Radium in Water (RAW03) Eichrom Technologies, Inc.
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General Engineering Laboratories, Inc. Charleston, SC Test #1 Results SampleVolume (g) % Yield ( 133 Ba) Activity (pCi/g) Uncertainty 2-Sigma (pCi/g) MDA (pCi/g) FWHM (keV) % Recovery 1 (Sample) 1.0196.63.700.410.05142 2 (Sample) 0.59101.13.560.460.07172 3 (Sample) 1.0792.63.550.400.04417 4 (Blank) 1.0098.2-0.010.020.073 5 (Matrix Spike) 0.5898.821.201.820.0930092.6 6 (Lab Control Sample) 1.00100.611.000.950.0580100.9
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General Engineering Laboratories, Inc. Charleston, SC Test #1 Spectra Sample 1
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General Engineering Laboratories, Inc. Charleston, SC Test #1 Spectra Sample 3
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General Engineering Laboratories, Inc. Charleston, SC Test #1 Spectra Sample 6 (LCS)
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General Engineering Laboratories, Inc. Charleston, SC Problem with initial testing: Resolution exceeded 100keV –Suspected cause was from natural Barium in the soil.
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General Engineering Laboratories, Inc. Charleston, SC Proposed solutions: Use less sample Use less Barium Carrier –100 L of 0.75 mg/mL Barium Carrier was used for Test #1 Use less Seeding Suspension
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General Engineering Laboratories, Inc. Charleston, SC Test #2 Analyze 3 samples with No Barium Carrier Analyze 3 samples with 50 L of Barium Carrier Vary aliquot size from 0.1g to 0.5g
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General Engineering Laboratories, Inc. Charleston, SC Test #2 Results SampleVolume (g) % Yield ( 133 Ba) Activity (pCi/g) Uncertainty 2-Sigma (pCi/g) MDA (pCi/g) FWHM (keV) 1 No Barium 0.4793.23.840.080.09177 2 No Barium 0.2599.14.040.430.06105 3 No Barium 0.1692.53.680.550.1596 4 50µL Barium 0.4897.93.790.360.01129 5 50µL Barium 0.2595.43.780.440.12172 6 50µL Barium 0.1096.63.850.580.26104
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General Engineering Laboratories, Inc. Charleston, SC Problem with Test #2: Resolution on samples with reduced Barium Carrier continue to exceed 100keV
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General Engineering Laboratories, Inc. Charleston, SC Test #2 Spectra Sample 1
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General Engineering Laboratories, Inc. Charleston, SC Test #2 Spectra Sample 3
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General Engineering Laboratories, Inc. Charleston, SC Test #3 Used 0.1mL of the seeding suspension 0.2mL used previously No Barium Carrier was used
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General Engineering Laboratories, Inc. Charleston, SC Test #3 No Barium Yields FAILURE
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General Engineering Laboratories, Inc. Charleston, SC Test #4 Comparison of Alpha Spec vs. Emanation Alpha Spec –Used 0.2g of sample –50 L of Barium Carrier Emanation used 0.5g of sample
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General Engineering Laboratories, Inc. Charleston, SC Test #4 Results SampleVolume (g) % Yield ( 133 Ba) Activity (pCi/g) Uncertainty 2-Sigma (pCi/g) MDA (pCi/g) FWHM (keV) Alpha Spec Run 10.2061.75.041.120.48172 20.2045.53.311.080.6099 Emanation Run 10.514.250.840.31 20.514.530.960.59
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General Engineering Laboratories, Inc. Charleston, SC Test #4 Spectra Sample 1
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General Engineering Laboratories, Inc. Charleston, SC Test #4 Spectra Sample 2
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General Engineering Laboratories, Inc. Charleston, SC Update to the Objective Further discussions with the client revealed they were never able to achieve resolution <100keV –They re-set their requirement to <250keV Current testing Average FWHM –149keV –Consistently <200keV
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General Engineering Laboratories, Inc. Charleston, SC Changes to 226 Ra Water Procedure Ensure that 0.5g or less of soil used –Minimizes natural Barium introduced Reduce Barium carrier used –50µL 0.75mg/mL
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General Engineering Laboratories, Inc. Charleston, SC In Conclusion Original FWHM Goal (<100keV) not achieved –Client changed their requirement to <250keV Average FWHM for soils 149keV Faster Turn Around Times accomplished –Soils can be run in 2 days Emanation 3 day minimum Gamma 7-30 day minimum –Waters can be run in 1 day
