Radioactive Decay Calculation: Activity of one milli Curie of P-Labelled ATP After 60 Days
Calculate the activity of one milli Curie of P-labelled ATP after 60 days. If the half life is 12 days.
(a) 125 micro Curie
(b) 250 micro Curie
(c) 62.5 micro Curie
(d) 31.25 micro Curie
Final Answer: (D) 31.25 µCi
Thus, the correct answer is (D) 31.25 µCi. This aligns with the principles of radioactive decay, where each half-life reduces the substance’s activity by half.
Understanding Radioactive Decay
Radioactive decay is a natural process in which an unstable isotope loses energy by emitting radiation. The rate of decay is measured by a parameter known as the half-life, which is the time required for half of the radioactive substance to decay. The decay follows an exponential pattern, meaning that after each half-life, only 50% of the remaining substance remains.
In this problem, we have P-labeled ATP with:
- Initial Activity = 1 milliCurie (mCi) = 1000 microCurie (µCi)
- Half-life = 12 days
- Total time elapsed = 60 days
Understanding the Concept
Radioactive isotopes decay over time based on their half-life. A half-life is the time required for half of a radioactive substance to decay. In this case, the half-life of P-labeled ATP is 12 days, so the activity decreases as follows:
- After 12 days → 1000 → 500 µCi
- After 24 days → 500 → 250 µCi
- After 36 days → 250 → 125 µCi
- After 48 days → 125 → 62.5 µCi
- After 60 days → 62.5 → 31.25 µCi
Significance of This Calculation
This calculation is crucial in biomedical research, nuclear medicine, and molecular biology, particularly in:
- Radioactive Tracing – Used in experiments involving labeled nucleotides for DNA sequencing or protein labeling.
- Medical Imaging – Important in PET scans and radiotherapy, where precise activity measurements ensure patient safety.
- Pharmaceutical Research – Used in studying drug metabolism and biological interactions.
Conclusion
Using the radioactive decay formula, we determined that after 60 days, the activity of 1 mCi of P-labeled ATP will decrease to 31.25 µCi. Understanding half-life decay helps in numerous scientific and medical applications, ensuring accurate dosing and experiment design.
4 Comments
Nisha
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Arushi
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March 20, 2025👍👍
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April 1, 2025👍