basic molarity/curie question

Dr E. Buxbaum EB15 at
Wed Nov 6 14:24:46 EST 1996

otterpop at (Otter) wrote:
>I am trying to figure out the molarity of my reaction.  I am using
>tritiated s-adenosyl-methionine which has a specific activity of 55.1
>Ci/mmol.  I am using 2 micro Ci in my reactions.  How many micro moles is
>that?  Since I am trying to learn how to perform this calculation, can you
>please show me how you come up with the molarity.
>Thanks for your time and help,

if 1 mmol has 55.1 Ci, then 2 uCi correspond to 0.000002 Ci * 0.001 mol / 
55.1 Ci = 36.3 pmol. Divide this by the volume of your assay (in 
liter) and you get your concentration in pmol/l or pM.

The trick is always to work in basal units. Write down all walues with 
their units and check, that the result will have the correct unit. Then 
do the calculation itself. 

By the way, strictly speaking you should be working with Bq, not Ci.

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