Gas-phase sorption-desorption of propargyl bromide and 1,3-dichloropropene on plastic materials

The goal of this research was to provide information for choosing appropriate materials for studying gas-phase concentrations of propargyl bromide (3BP) and 1,3-dichloropropene (1,3-D) in laboratory experiments. Several materials were tested and found to sorb both gas-phase chemicals in the following order: stainless steel (SS) < Teflon polytetrafluoroethylene (PTFE-FEP) ≃ flexible polyvinyl chloride (PVC) = acrylic < low-density polyethylene (PE) < vinyl silicone < polyurethane foam (PUF). Sorption of SS was insignificant and PUF sorbed all the fumigant that was applied. For the other materials, linear sorption coefficients (K d ) for 3BP ranged from 3.0 cm 3 g -1 for PVC to 215 cm 3 g -1 for silicone. Freundlich sorption coefficients for 1,3-D ranged from 11.5 to 371 cm 3 g -1 . First-order desorption rate constants in an open system ranged from 0.05 to 1.38 h -1 for 3BP and from 0.07 to 1.73 h -1 for 1,3-D. In a closed system, less than 2% of sorbed fumigant desorbed from vinyl while up to 99% desorbed from PVC within 24 h when equilibrated at the highest headspace concentration. Sorption of both fumigants was linearly related to the square root of time except for vinyl and silicone. This may indicate non-fickian diffusion of fumigant into the polymer matrix. Vinyl, silicone, PE, and PUF should be avoided for quantitative study of organic gases, except possibly as a trapping medium. Use of PTFE, PVC, and acrylic may require correction for sorption-desorption and diffusion.