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Monday, 16 September 2019
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Raw materials & technologies, Applications

Partitioning properties of silicone for passive sampling of PCB in indoor air

Monday, 11 July 2016

The former use of polychlorinated biphenyls (PCBs) in construction materials can lead to elevated indoor air concentrations. Danish researchers studied the partitioning of PCB congeners between indoor air and silicone with a view to establish passive sampling of PCBs.

Varying air velocity can affect silicone-indoor air partitioning of polychlorinated biphenyls (PCBs). Source: alexvav/Fotolia.com

Varying air velocity can affect silicone-indoor air partitioning of polychlorinated biphenyls (PCBs). Source: alexvav/Fotolia.com

The release of PCB congeners from silicone followed first order kinetics and confirmed air-side rate-limited mass transfer. Logarithmic elimination rate constants decreased linearly with the logKOA values of the PCB congeners, but varied in a non-linear way with air velocity. Linear uptake of PCBs was found for silicone disks (0.5 mm thickness) in a petri dish, while PCBs reached equilibrium in silicone-coated paper sheets (0.001 mm silicone on each side) exposed to indoor air for 1–2 weeks.

Prototype samplers show high sensitivity and precision

The ratios of equilibrium concentrations in silicone and conventionally measured air concentrations were roughly comparable with silicone-air partition coefficients, but further research is required for the determination of silicone-air partition coefficients. Avoiding performance reference compounds (PRCs) because of the indoor setting, the two formats were calibrated against conventional active measurements. Comparisons of air concentrations derived from active and kinetic passive sampling showed a divergence by factors of 2.4 and 2.0 (median values) for the petri dishes and the silicone-coated paper, respectively. With promising results for sensitivity and precision, the calibration of kinetic passive samplers remains the main challenge and will need suitable, non-hazardous PRCs. Equilibrium sampling indicated promising alternatives.

The study is published in: Chemosphere, Volume 160, October 2016, Pages 280–286

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