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Preparation of (228)Ra standard solution
1Czech Metrology Institute, Radiová 1, 102 00 Prague, Czech Republic.
Summary
Researchers developed two methods to isolate radium-228 (228Ra) from thorium-232 (232Th) salt for preparing standard solutions. These techniques ensure a pure 228Ra standard with high accuracy, crucial for radiological measurements.
Area of Science:
- Radiochemistry
- Nuclear Chemistry
- Analytical Chemistry
Background:
- Accurate standard solutions of radionuclides are essential for quantitative measurements in nuclear science and environmental monitoring.
- Thorium-232 (232Th) is a naturally occurring radioactive element that decays to produce various isotopes, including radium-228 (228Ra).
- Separating radium isotopes from thorium parent isotopes presents analytical challenges due to their similar chemical properties.
Purpose of the Study:
- To develop and validate simple, effective methods for isolating radium-228 (228Ra) from thorium-232 (232Th) salt.
- To prepare a high-purity standard solution of 228Ra suitable for calibration and quantitative analysis.
- To establish the activity of 228Ra in the standard solution with a low degree of uncertainty.
Main Methods:
- Two distinct methods for thorium-radium (Th-Ra) separation were developed, leveraging the differential solubility of thorium nitrate in organic solvents.
- Method 1: Co-precipitation of radium with lead (Pb) in the form of lead nitrate (Pb(NO3)2) from an acetic acid solution.
- Method 2: Solvent extraction, where thorium remains in the organic phase while radium is concentrated in the aqueous phase.
Main Results:
- The developed methods successfully isolated 228Ra from 232Th salt, yielding a standard solution with activity up to 20 kBq.
- Gamma-ray spectrometry was used to relate the activity of 228Ra to a 232Th standard, achieving an uncertainty of less than 0.7% (k=1).
- The final standard solution was confirmed to be free of 232Th and contained standard carrier concentrations of BaCl2 and HCl.
Conclusions:
- The study successfully established two straightforward and efficient methods for Th-Ra separation.
- A reliable standard solution of 228Ra was prepared with high accuracy and low uncertainty, suitable for radiological applications.
- These methods provide a valuable tool for researchers requiring precise 228Ra standards for various scientific disciplines.