A method for partitioning dissolved polycyclic aromatic hydrocarbons associated with humic substances using polyethylenimine-coated glass fiber filters

Abstract

The use of a glass fiber filter coated with polyethyleneimine (PcGF) for partitioning dissolved polycyclic aromatic hydrocarbons (PAHs) that are associated with humic substances (HSs) is reported. The PAHs pass through the PcGF, while HS-associated PAHs are trapped by electrostatic interaction between the HSs and the PcGF. Based on this strategy, free- and associated-PAHs can be separated by simple filtration. Approximately 60–90% of the deuterated benzo[a]pyrene (BaP-d12) that was added to the sample solutions was in the associated form with soil type HAs, while the percentages were lower in the case of aquatic HA (ca. 25%) and FAs (ca. 10–15%). Strong correlations (R² = 0.84–0.90) were observed between the %-association for deuterated pyrene (Pyr-d10) or BaP and the degree of HS's aromaticity (log E₂₈₀), regardless of the HS fractions or their origins. The separation technique was used to evaluate the association coefficient (log K_assoc) and the capacity (C_assoc) for soil type HAs based on a Langmuir adsorption model. The log K_assoc values were not highly dependent on the origin of the HA (ca. 3.5–4.5). The BaP-d12 and Pyr-d10-C_assoc values for the HA derived from compost were more than one order larger than the corresponding values for peat. The findings indicate that C_assoc values vary with the origin of the HA and affect the environmental behavior of PAHs. The present study reports on the development of a simple partitioning technique that does not require any special training and equipment.