TITLE
THEORETICAL EVALUATION OF STABILITY OF VOLATILE 
ORGANIC CHEMICALS AND POLAR VOLATILE ORGANIC CHEMICALS IN CANISTERS

AUTHOR(S)
R. W. COUTANT

PERFORMING ORGANIZATION NAME AND ADDRESS
Battelle
505 King Avenue
Columbus, Ohio 43201-2693

SPONSORING AGENCY NAME AND ADDRESS
Atmospheric Research & Exposure Assessment Lab
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711

ABSTRACT
     The potential for physical adsorption as a mechanism for loss
of volatile organic chemicals (VOC) and polar volatile organic
chemicals (PVOC) from the vapor phase in canister samples was
assessed using the principles embodied in the Dubinin-Radushkevich
isotherm.  This isotherm provides a specific relationship between
the tendency for adsorption and compound/sample specific properties
such as polarizability, vapor concentration, temperature, and
equilibrium vapor pressure.  In addition, the isotherm provides a
means for distinguishing between surfaces having different physical
and chemical properties.  A computer-based model was developed for
predicting adsorption behavior and vapor phase losses in
multicomponent systems based on the potential for physical
adsorption as well as the potential for dissolution in condensed
water for samples collected at high humidities.  At present, the
data base for the model contains relevant physicochemical data for
78 compounds (including water), and provisions for inclusion of up
to 120 additional compounds are incorporated in the software.