Determination of polyaromatic hydrocarbons in river water using a sorbent consisting of removable octadecyltrimethylammonium ions attached to cation exchange silica in conjunction with commercial C18silica

Abstract

An application that highlights the usefulness of a solid phase extraction sorbent having a removable surfactant “stationary phase” is introduced. Polyaromatic hydrocarbons (PAHs) efficiently trap on commercially available non-polar sorbents (i.e., C₁₈ silica). However, solvents that are necessary to break strong hydrophobic interactions between the analyte and sorbent are harmful and incompatible for direct introduction into a reversed phase liquid chromatographic setup. In the presented approach, the entire “stationary phase”–analyte association is removed, resulting in very efficient elutions with a final extract that is mild and reversed phase liquid chromatographic compatible. Commercial C₁₈ silica was placed adjacent to this sorbent to provide more efficient trapping of less hydrophobic PAHs. PAHs were preconcentrated from river water and were determined using fluorescence detection coupled to HPLC. Detection limits for all PAHs examined were in the sub µg L⁻¹ level.