Not to be pedantic, but tritium is what hydrogen with 1 proton and 2 neutrons is called. It is tritium whether it is in pure (T-T), or heterogeneous (T-x) form.
It is gaseous when part of a gaseous molecule, and solid or liquid when parts of molecules in those phases.
Since it has identical properties with standard, single-nucleon, hydrogen; it can be substituted in a molecule almost anywhere hydrogen can.
I used to use tritiated compounds to track drug distribution in animals it works great for that too.