A solid-phase microextraction coating of sol-gel-derived perhydroxy cucurbit[6]uril and its application on to the...

A novel solid-phase microextraction coating that contains perhydroxy cucurbit[6]uril((OH)₁₂Q[6]) was prepared by a sol-gel method. (OH)₁₂Q[6] was used as a starting coating material with hydroxy-terminated poly(dimethylsiloxane) (OH-PDMS) to bond chemically to a fused-silica substrate using 3-(2-cyclooxypropoxyl)propyltrimethoxysilane as cross-linking agent; hydrolysis and polycondensation reactions then led to the formation of a (OH)₁₂Q[6]/PDMS-coating. The coating has a high thermal stability (360°C), long lifetime and can withstand organic and inorganic solvent rinsing because of the chemical binding between the coating and silica substrate. Its performance was tested by headspace (HS) solid-phase microextraction fiber coupled with gas chromatography to determine polycyclic aromatic hydrocarbon (PAHs) compounds in water samples. The (OH)₁₂Q[6]/PDMS-coated fiber exhibited higher enrichment factors from fourfold for naphthalene to tenfold for pyrene compared with commercial PDMS fiber, and the enrichment factors increased with the number of condensed PAH rings. The strong adsorption affinity is believed to be attributed to hydrogen bonding and CH⋯π interactions between PAHs and (OH)₁₂Q[6], according to the results of quantum chemical calculations. In the PAH analysis, the (OH)₁₂Q[6]-coated fiber showed a good repeatability (<4.7%) and reproducibility between fibers (<9.4%), low detection limits (0.03-0.15μgL^-1), and a wide linearity (0.1-1000μgL^-1) under optimized conditions. This method was used for the simultaneous determination of seven PAHs with satisfactory recoveries of 90.56%-107.4% for Huaxi river water samples and 90.23%-109.5% for local wastewater samples, respectively.