Pseudostationary Phase for Solid Phase Extraction

A unique pseudostationary phase for Solid Phase Extraction is presented. This pseudostationary phase consists of surfactant, which is initially immobilized onto hydrophilic cation exchange resin. The surfactant chain through hydrophobic interactions extracts hydrophobic analytes in the same manner as conventional bonded alkyl moieties on silica based non-polar sorbents. Although hydrophobic analytes can be efficiently trapped on commercially available non-polar sorbents (i.e. Ci8 silica), organic solvents that are necessary to break strong hydrophobic interactions between the analytes and the sorbent are harmful. They are also incompatible for direct introduction into a reversed phase liquid chromatographic set up. In the presented approach, the entire pseudostationary phase may be removed via ion exchange in very mild aqueous solutions, resulting in very efficient elutions with a final extract that is mild and reversed phase liquid chromatographic compatible. Rinse solution parameters were optimized and various cationic surfactants attached to cation exchangeable silica including silica modified with sulfopropyl groups and unmodified silica were investigated to reach sufficient sorbent hydrophobicity to capture EPA 16 priority polycyclic aromatic hydrocarbons (PAHs). PAHs were preconcentrated from river water and were determined using fluorescence detector coupled to high performance liquid chromatography (HPLC). Detections limits for all PAHs examined were lower than EPA\u27s maximum contaminant level