  Rare event searches require extreme radiopurity in all detector components.
This includes the active medium, which in the case of gaseous detectors, is the
operating gas. The gases used typically include noble gas mixtures with
molecular quenchers. Purification of these gases is required to achieve the
desired detector performance, however, purifiers are known to emanate 222 Rn,
which is a potential source of background. Several purifiers are studied for
their O 2 and H 2 O purification efficiency and Rn emanation rates, aiming to
identify the lowest-Rn options. Furthermore, the absorption of quenchers by the
purifiers is assessed when used in a recirculating closed-loop gas system.
