Application of Response Surface Methodology to Analyze the Effects of Soil/Liquid Ratio, pH, and Incubation Time on the Bioaccessibility of PAHs from Soil in In Vitro Method

Central composite design using response surface methodology was employed to optimize soil/liquid ratio (S/L), pH, and incubation time for polycyclic aromatic hydrocarbons (PAHs) bioaccessibility from soil in a simulated gastrointestinal tract. The magnitude of PAHs bioaccessibility in intestinal tract was found higher than that in gastric tract. Results showed that S/L had significant negative effects on the bioaccessibility of PAHs in both the gastric and intestinal tracts. The effect of pH on the intestinal tract was significantly negative, while on the gastric tract, it was positive. The incubation time presented an insignificant effect in gastric tract despite its significant positive effect in intestinal tract. The worst-case bioaccessibility conditions for PAHs in the gastric tract were found to be S/L 0.004, pH 2, and incubation time 3 h, with the maximum bioaccessibility of PAHs at 6.0% compared with 41.8% in intestinal tract with S/L 0.004, pH 6.5, and incubation time 6 h.