Tenax as sorption sink for in vitro bioaccessibility measurement of polycyclic aromatic hydrocarbons in soils

Physiologically based in vitro methods have been developed to measure bioaccessibility of organic contaminants in soils. However, bioaccessibility of hydrophobic organic contaminants (HOCs) can be underestimated by in vitro tests if gastrointestinal (GI) solution fails to provide sufficient sorption sink for HOCs. To circumvent this drawback, Tenax was included in GI solution as sorption sink to trap mobilized HOCs and maintain the desorption gradient between soil and GI solution. Polycyclic aromatic hydrocarbons (PAHs) were selected as target HOCs, and physiologically based extraction test (PBET) was selected as the in vitro method. Inclusion of Tenax in GI solution increased bioaccessibility of PAHs in five spiked soils from 8.25-20.8% to 55.7-65.9% and the bioaccessibility of PAHs in a field contaminated soil from 3.70-6.92% to 16.3-31.0%. Our results demonstrated the effectiveness of Tenax as sorption sink to enhance PAH mobilization in bioaccessibility measurement in soils.