Editing Radioactive tracer (section)

===Phosphorus===
[[phosphorus-32|<sup>32</sup>P]] is made by neutron bombardment of [[sulfur|<sup>32</sup>S]]
:[[sulfur|<sup>32</sup>S]] + [[neutron|n]] → [[phosphorus-32|<sup>32</sup>P]] + [[proton|p]]
It decays by beta decay with a half-life of 14.29 days. It is commonly used to study protein phosphorylation by [[kinases]] in biochemistry.

[[phosphorus-33|<sup>33</sup>P]] is made in relatively low yield by neutron bombardment of [[phosphorus|<sup>31</sup>P]]. It is also a beta-emitter, with a half-life of 25.4 days. Though more expensive than [[phosphorus-32|<sup>32</sup>P]], the emitted electrons are less energetic, permitting better resolution in, for example, DNA sequencing.

Both isotopes are useful for labeling [[nucleotide]]s and other species that contain a [[phosphate]] group.