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Considerations of acidifying water samples for 99Tc analysis
R L Blanchard1, R Lieberman, W S Richardson
1S. Cohen and Associates, Inc., Montgomery, AL 36115-2601.
Health Physics
|August 1, 1993
Summary
Acidifying environmental water samples to pH 1.7 with nitric acid and evaporating them prevents technetium-99 (99Tc) volatilization before analysis. Avoid flaming planchets without detergent to prevent activity loss.
Area of Science:
- Environmental science
- Analytical chemistry
- Radiochemistry
Background:
- Radionuclide analysis of environmental water requires sample acidification to prevent adsorption.
- Potential volatilization of technetium-99 (99Tc) during sample evaporation is a concern for accurate beta analysis.
Purpose of the Study:
- To investigate the potential for technetium-99 (99Tc) volatilization from acidified water samples during evaporation.
- To determine optimal conditions for sample preparation prior to beta analysis of 99Tc.
Main Methods:
- Environmental water samples were acidified to pH 1.7 using nitric acid.
- Samples were evaporated to dryness on planchets.
- The effect of flaming planchets on 99Tc activity was assessed, with and without detergent.
Main Results:
- Acidification to pH 1.7 with nitric acid and subsequent evaporation to dryness did not cause significant volatilization losses of 99Tc.
- Flaming of planchets without the use of a detergent resulted in activity loss.
- Control samples are necessary to quantify activity loss under specific flaming conditions.
Conclusions:
- Evaporation of acidified environmental water samples (pH 1.7) is a suitable method for preparing samples for 99Tc beta analysis.
- Care must be taken when flaming planchets; detergent use or control sample analysis is recommended to account for potential activity loss.