The use of nonresonance lines in atomic absorption has usually been restricted to those elements which have a fairly closely spaced multiplet ground state or in theoretical studies to give a measure of the temperature of a flame. Our research into the use of porous graphite flameless atomizer sample cups as air filters pointed to a need for a way to occasionally reduce the sensitivity of these devices for lead determinations. In these analytical applications, air to be sampled is first drawn through the walls of a porous Woodriff furnace cup or a porous carbon rod atomizer tube and then the cup (or tube) is placed directly into the atomizer for the lead determination without any chemical or physical pretreatment of the sample.
Darryl Duane Siemer and Ronald Wayne Stone, "Analytical Potential of Nonresonance Line Flameless Atomic Absorption Spectrometry for Lead Determination," Appl. Spectrosc. 29, 240-244 (1975)