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Decreased benzo(a)pyrene concentration in rapeseed oil packed in polyethylene terephtalateCommercially available rapeseed oil, the same oil additionally refined physically, and paraffin oil for comparison purposes were spiked with benzo(a)pyrene (BaP) at the level of 29.4, 34.3, and 50.4 mg kg 21, respectively, filled into polyethylene terephtalate (PET) cylindrical-shape receptacles, and the BaP concentrations were followed within 73 h by HPLC analysis. During this time, the BaP concentrations decreased to 22.9, 25.4, and 23.5 mg kg 21 due to sorption of BaP onto PET. Using a modified kinetic equation, diffusion coefficients of BaP in all oils were calculated. The values of the diffusion coefficients and distribution coefficients indicated that other compounds present in the oils competed with BaP and affected the rate of BaP diffusion in the oils and the extent of adsorption onto PET. Moreover, the curves of BaP concentration vs. time, obtained experimentally, exhibited oscillations in BaP concentrations around the adsorption curves calculated by the kinetic equation. This was observed especially at the initial stages of the experiments, with the subsequent establishing of steady equilibrium BaP concentrations between liquid and solid phases at the end of the experiments, which does not correspond with known theory of adsorption.

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