A breath gas analysis module for supplying a sample gas to a gas detector includes a manifold having a body defining a chamber therein. The chamber includes a main passage extending through the manifold body, an outlet passage extending into the manifold body from an outlet end at a base of the manifold body and toward the main passage and a metering orifice extending between and in fluid communication with the main passage and an interior end of the outlet passage. An inlet tube is attached to the manifold body at one end of the main passage and defines an internal passage in fluid communication with the main passage. A collection tube is attached to the manifold body at another end of the main passage and defines an internal passage in fluid communication with the main passage. A check valve is positioned within the inlet tube internal passage and is oriented to permit fluid flow into, but not back from, the main passage. A resilient gas reservoir is attached to a free end of the collection tube opposite an end thereof attached to the manifold body. The resilient gas reservoir defines a storage chamber therein which is in fluid communication with the collection tube internal passage.