A system to study mineralization of volatile organic compounds (VOCs) was developed using commercially available solid-phase VOC traps and impingers to collect CO2 as well as VOCs breaking out from the solid-phase trap. The efficiencies of VOC traps containing activated charcoal (AC) or graphitized carbon black (GCB) for adsorbing [14C]trichloroethylene ([14C]TCE) and 14CO2 were evaluated and approaches for minimizing VOC losses from reaction vessels established. Mass balances showed AC and GCB adsorbed similar amounts of [14C]TCE. But, GCB had no detectable 14CO2 retention while AC absorbed about 7% of the 14CO2. Because 14CO2 absorption could influence the interpretation of mineralization experiments, GCB was concluded to be the better VOC-trapping matrix.