Hello.
I want to ask the method about the conversion from the result of Liquid scintillation counting (LSC) to molarity.
For example, when I measure LSC with 12ml (cocktail) + 8ml (radiolabeled sample)
Sample : HCO2-, TCO2- (tritiated formate) mixture with unknown ratio.
If I get the LSC results of this samples (1000 bq/ml), how to know the molarity of TCO2- ?
Thank you.
Of the result, 1000 Bq/ml refers to the full volume, then the total activity Will be 20,000Bq, the concentration of the original solution is 2500 Bq/ml, (2500000 Bq/liter). The Molar activity of the tritium (T2) is 2.142*10^15 Bq/mol. But in the molecule is only one tritium atom so we ide the half of this value. The molarity of the tritiated compound would be 2500000/1.071*10^15 mol/liter.
Thank you. Dr. Pal Mikecz
I have some doubts to your solution.
1. LSC measurement is performed by mixing 12 ml of a cocktail solution that converts the kinetic energy of radioactive particles into light, and 8 ml of a radiolabeled sample.
The measured value can be obtained in dpm, and the value obtained by (dpm/60)/(volume of sample;8ml) is 1000 bq/ml.
In this case, can I calculate the original concentration as 1000 bq/ml?
2. Is molar activity a converted value of specific activity?
3. Could you please recommend any literature(journal, textbook, etc) that I can study to in relation to these calculation formulas?
Thank you again
Best regards
SeongBeom Jeon.
Assuming the 1,000 Bq/ml is for the sample material, and using a half-life of 12.32 years for tritium, I get 5.609 E +11 atoms of H-3/ml, or 9.317 E-10 Molar.
Dear Seongbeom Jeon ,
It was not clear, to which volume was referred the 1000 Bq/ml. In your answer, it is clear that is for the original (8 ml) solution. Then of course you can omit the first step of my calculation. This way the final equation would be 2500000/1.071*10^15 = 9,34*10^-10 mol/liter.
This is a similar result that was given by William Uhland . The difference is the source of data of the half life of tritium.
I could recommend you any basic textbook about Radiochemistry. Better if you look for it in your environment. The most comprehensive one is perhaps: Handbook of Nuclear Chemistry: Vol. 1: Basics of Nuclear Science; Vol. 2: Elements and Isotopes: Formation, Transformation, Distribution; Edition
by Attila Vértes (Editor), Sándor Nagy (Editor), Zoltán Klencsár (Editor), Rezso György Lovas (Editor), Frank Rösch (Editor)
Best regards
Pal Mikecz
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