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Where do 35S and 32P come from?

  1. May 13, 2008 #1
    Hi all,

    I remember a long time ago in highschool our bio teacher mentioned that radiotracers used in biology back in the 40s-50s came out of the Manhattan project.

    But searching through google, i haven't really been able to find which radiotracers that we commonly use in biology come from decaying uranium/plutonium etc.

    2 of the big radiotracers we use are [tex]^{35}S[/tex] and [tex]^{32}P[/tex]. Normally sulfur is used to label proteins and phosphorus is used to label DNA (although [tex]^{32}P[/tex] is useful for phosphorylation states of proteins too)

    There are also others used such as [tex]^{123}I[/tex] and [tex]^{125}I[/tex].

    Many of these (particularly [tex]^{32}P[/tex]) have incredibly short half-lives so I'd imagine if they weren't being made from something with a much longer 1/2 life they'd have burned out of the universe long ago. So where do they come from and how are they made?
    Last edited: May 13, 2008
  2. jcsd
  3. May 13, 2008 #2


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    They aren't made from heavy metal decay but from neutron irradiation of smaller atoms -
    for which you need a reactor.
    Today they are generally made in small specialised reactors or as a side product in a few powerstations.
    Very short lived isotopes you have to make on-site in an accelarator and then inject them directly into the patient - often involving a frantic sprint accross the hospital.
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