Resonant laser ionization and mass separation of 225 Ac

^225 Ac is a radio-isotope that can be linked to biological vector molecules to treat certain distributed cancers using targeted alpha therapy. However, developing ^225 Ac-labelled radiopharmaceuticals remains a challenge due to the supply shortage of pure ^225 Ac itself. Several techniques to obtain pure ^225 Ac are being investigated, amongst which is the high-energy proton spallation of thorium or uranium combined with resonant laser ionization and mass separation. As a proof-of-principle, we perform off-line resonant ionization mass spectrometry on two samples of ^225 Ac, each with a known activity, in different chemical environments. We report overall operational collection efficiencies of 10.1(2)