Aspects on the analysis of 210Po

Area of Science:

• Environmental Science
• Radiochemistry
• Analytical Chemistry

Background:

• Polonium (Po) analysis in environmental samples has seen limited advancement since the 1960s.
• Traditional methods rely on spontaneous deposition on metals like silver (Ag), nickel (Ni), or copper (Cu) without radiochemical separation.
• Previous assumptions of 100% yield and the use of less accurate counting methods led to underestimations of Po losses.

Purpose of the Study:

• To quantitatively assess polonium (Po) losses during wet-ashing procedures.
• To compare the efficiency of different sample preparation techniques (open glass beakers, microwave digestion, Kjeldahl flasks) for minimizing Po losses.
• To investigate systematic errors in Po and lead-210 (Pb) measurements arising from electrochemical deposition and detector contamination.

Main Methods:

• Utilized a double-tracer technique to evaluate Po losses during wet-ashing.
• Compared Po losses across various digestion methods: open glass beakers, microwave ovens, and long-necked bottles (Kjeldahl flasks).
• Assessed the fraction of lead-210 (Pb) plating out with Po during electrochemical deposition and evaluated Po evaporation during alpha spectrometry measurements.

Main Results:

• Po losses during wet-ashing were approximately 30% in open glass beakers, 17% with microwave digestion, and 20% in Kjeldahl flasks.
• Significant amounts of lead-210 (Pb) (50-90%) plated out with Po, causing systematic errors in Po/Pb ratio calculations.
• Heating discs after deposition indicated less Po evaporation from silver (Ag) than nickel (Ni), with Ag showing lower overall losses.

Conclusions:

• Microwave digestion significantly reduces polonium (Po) losses during wet-ashing compared to open beakers or Kjeldahl flasks.
• Electrochemical deposition of lead-210 (Pb) introduces systematic errors in polonium (Po) and lead-210 (Pb) measurements.
• Silver (Ag) is the preferred plating metal for polonium (Po) analysis due to lower evaporation losses and better retention.