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Star Republic: Guide for Biologists

Liquid scintillation counter efficiency

1. Prepare a dilution of radioisotope sample with known activity. A series of dilution may be needed since the scintillation counter may saturate if the radioactivity is too high.

2. Add appropriate amount of scintillation cocktail to scintillation vials.

3. Add your samples to scintillation cocktails in the vials.

4. Also prepare a vial with only scintillation cocktail as control.

5. Turn on the counter, select an appropriate program for your isotope. (If program not stored, check user manual on how to setup a program).

6. Press start. Stop when counting is done.

7. Dispose counted vials and scintillation cocktail as hazardous waste.

8. For beta decay, the radioactivity can be calculated from disintegration per minute (dpm). There should be a liner relationship between the counts per minute (cpm) measured by liquid scintillation and dpm.

counter efficiency = count per minute (cpm)/disintegration per minute (dpm)

See Liquid scintillation counter and Liquid scintillation counting.