POTENTIAL ROUTE EVIDENCE FROM FUGITIVE CHEMICALS ADSORBED TO PACKAGING MATERIALS AND METAL OXIDES

Common polymeric materials used in packaging, such as paper and plastics (e.g. zip-lock bags), rapidly adsorb organic vapors and can retain them for weeks to months after short-term exposures. In a blind test, a piece of low-density polyethylene (LDPE) was placed into possession of an individual for 7 days, returned to us after a few hours of open room-air exposure, solvent extracted, and analyzed by gas chromatography-mass spectrometry. Results revealed ~50 unique organic species not found in an unexposed LDPE. The identification of these species is consistent with ambient vapors common in the individual’s personal environment (e.g., tobacco smoke). Dynamic and open system exposure characteristic of this example were quantified for tributyl phosphate (Vp ~1e-6 atm) which reached steady-state accumulation onto brown paper and LDPE within 72 hours. After 50 days of passive desorption, >1% of the initial amount remained. Analyses have been extended to adsorbed compounds on high purity and technical grades of uranium and other metal oxides using solid phase micro-extraction techniques. In almost all cases results show 10s to 100s of individual organic species are adsorbed to these materials. Boiling point range and tentative identification of these species indicate these compounds record vapor and solvent exposure in previous environments which may reflect conditions during processing, storage and distribution. The results of this work and previous literature support measuring fugitive organic chemicals adsorbed to various material substrates as a forensic tool.