Solid phase extraction of 16 polycyclic aromatic hydrocarbons from environmental water samples by π-hole bonds

Through theoretical computation, it was demonstrated that perfluorobenzene can form π-hole⋅⋅⋅π bonds with polycyclic aromatic hydrocarbons (PAHs). Then, the π-hole bond was firstly introduced in solid phase extraction in which perfluorobenzene-bonded silica sorbent was synthesized and used for the solid phase extraction of sixteen PAHs in water. Compared with the traditional octadecyl silica sorbent, the perfluorobenzene-bonded silica sorbent showed higher adsorbabilities for the PAHs with 4-6 benzene rings, for which the recoveries increased by approximately 20%. Under the optimized conditions, the proposed SPE-HPLC-FLD/UV method was successfully applied for the analysis of 16 PAHs in river water and waste water samples with the limits of detection ranged from 0.002 to 0.08 μg⋅L^-1. In addition, when the perfluorobenzene-bonded silica sorbent compared with the phenyl-bonded silica sorbent, the results indicated that π-hole⋅⋅⋅π bonds between perfluorobenzene and PAHs were stronger than the π-π interactions between the PAHs and benzene in hexane solution, which highlights the remarkable potential for the application of the π-hole bond in the SPE field.