Panasonic PT-DZ12000U Operating Instructions Manual page 127

E. Absorption and Adsorption
Absorption and adsorption are both used in air sampling
and are sometimes hard to distinguish from each other.
Absorption is a process in which atoms, molecules, or ions
enter some bulk phase - a gas, liquid, or solid material.
Adsorption is a process in which a gas or liquid aerosol
accumulates on the surface of a solid or liquid, forming a film
of molecules or atoms.
Sorption refers to both absorption and adsorption while
desorption is the reverse of either process.
Anhydrous calcium sulfate is an example of absorption
where water vapor (or tritium oxide) is collected by passing an
air stream through a cartridge containing the anhydrous
calcium sulfate. The moisture content of air can then be
measured by gravimetric or other methods and tritium oxide
in the air can be measured directly or indirectly using either a
radiation detector or liquid scintillation counting.
Silica gel, zeolites, and activated charcoal are examples of
adsorption where toxic or radioactive substances are
collected by passing an air stream through a cartridge
containing one of these materials. The radioactive
substances collected by these materials can be measured
directly or indirectly using radiation detectors. Toxic
substances collected by these materials are typically
extracted from the materials before they are measured.
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