Bitan:Calculating specific activity of hot CTP after calibration date
Calculating the specific activity of α-32P-CTP after the calibration date
CTP used is from Perkin Elmer: CTP, α-32P- 3000 Ci/mmol, 10 mCi/ml , 250 µCi.
Reference date for this lot was 11/21/09. The activity calculated for this lot on 11/27/09 is as follows:
This is CTP lot was 6 days old. The activity of α-32P-CTP, lot RSO0117175 was 0.748 of total activity on 11/27/09 based on the decay chart
According to this formula, the total activity was calculated to be 2447 Ci/mmol on 11/27/09:
where SAtheo.=9120 for the theoretical specific activity of carrier-free 32P; SAcal.=specific activity after the calibration date; and DF is the fraction of current radioactivity that will remain on the calibration date from the Decay Chart. So in this case
After the reference date, the total activity of the fresh hot CTP was 250 μCi in 25 μl, and the concentration was 10 μCi/μl (10 mCi/ml). But now, it is 187 μCi because 0.748×250=187. If 4 μl is used for in-vitro transcription reaction, the total amount used would be 4×187 μCi/25μl= 29.92=30 μCi for each reaction.