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Tc-99 Analysis in Air Filters, An Approach to Eliminate High Bias

Tc-99 Analysis in Air Filters, An Approach to Eliminate High Bias. Mitch Abbate Barringer Laboratories Golden, Colorado. Technetium. Discovered in 1937 by Segrè and Perrier First Element Produced Artificially Fission by-product 213,000 Year Half-life, Beta Emitter Very Soluble

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Tc-99 Analysis in Air Filters, An Approach to Eliminate High Bias

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  1. Tc-99 Analysis in Air Filters, An Approach to Eliminate High Bias Mitch Abbate Barringer Laboratories Golden, Colorado

  2. Technetium • Discovered in 1937 by Segrè and Perrier • First Element Produced Artificially • Fission by-product • 213,000 Year Half-life, Beta Emitter • Very Soluble • Can Cause and Help Diagnose Cancer

  3. Barringer Analysis of Tc-99 • Historically, Tc-99 extracted into TBP • Messy/ Difficult to meet TAT and MDL • Mixed Radioactive/ Organic Waste • Evaluation of Eichrom’s TEVA Resin • Simpler Procedure • No Mixed Waste • Concern over False Positives with Air Filters

  4. Eichrom TEVA Procedure • Oxidize Tc to TcO4-, Tc(VII) • Pass sample through TEVA Resin (pH=2) • Rinse Resin with 0.01 N HNO3 • Transfer Resin to LSC Vial • Add Cocktail • Count via LSC

  5. False Positives • Air Filter Samples • Pb-210 Possible Culprit • Pb-210 in U-238 Decay Chain • Beta Emitter/ Interference with Tc-99

  6. Pb-210? • Spiked Samples with 500 pCi Pb-210 • Up to 30% Activity Found on TEVA Resin via LSC • Tried ppt. Pb w/ FeOH • Slight Activity Reduction • Recounted Original Samples • Significant Activity Drop • Bi-210 Half-Life 5.01 days

  7. Bi-210 • Ca(PO4)2 ppt. • Good Results but Too Time Consuming • Bi uptake in HF on Strong Base Resin • No Adsorption • Ref. J.P. Feris, Anal. Chem., 32, 520 (1960)

  8. Re (VII) Uptake

  9. HF Evaluation • HF Added to Load Solution • Precipitation • Rinse with HF • Bi Removed to Near Background • Some Tc-99 Yield Reduction • Rinse with HF/Nitric Acid • Near 100% Tc-99 Recoveries: no Bi or Pb • TSIE’s best with 5 N HF although 1 N OK

  10. New Air Filter Method • Tc-99 Leach w/ 1 N Nitric • H2O2 + Heat to Insure TcO4- • Dilute to < 0.3 N Nitric Acid • Load on TEVA Resin (100-150µ) • 25 mL Rinse w/ 0.01 N Nitric • 20 mL Rinse w/ 5 N HF-0.01 N Nitric • 25 mL Rinse w/ 25 mL 0.01 N Nitric • Direct Addition of Resin to LSC Cocktail • After Dark Adaptation: LSC Counting

  11. TEVA RESIN

  12. Barringer Vacuum Box

  13. Summary • Method Used for All Sample Types • Tc-99 yields average >91% • Batch of 18 Samples (+ 6 QC) • 6 Hours Total Processing Time • Two Times Faster than TBP Method • Meeting Required Detection Limits • Eliminate Mixed Waste • Eliminate Reruns

  14. Acknowledgement • Jim Preston, Barringer Laboratories • Anil Thakkar and Larry Jassin, Eichrom • Phil Horwitz and Andy Bond, PGRF

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