Nanostructured-silver-coated polyetheretherketone tube for online in-tube solid-phase microextraction coupled with...

Polyetheretherketone tube is a better substrate for in-tube solid-phase microextraction than fused-silica capillary and metal tube because of its resistance to high pressure and good flexibility. It was modified with a nanostructured silver coating, and characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. It was connected into high-performance liquid chromatography equipment to build the online analysis system by replacing the sample loop of a six-port injection valve. To get the highest extraction capacity, the preparation conditions of the coating was investigated. Important extraction conditions including length of tube, sample volume, and desorption time were optimized using eight polycyclic aromatic hydrocarbons as model analytes. The tube exhibits excellent extraction efficiency toward them, with enrichment factors from 52 to 363. The online analysis method provides good linearity (0.5-100 or 1.0-100 μg/L) and low detection limits (0.15-0.30 μg/L). It has been used to determine polycyclic aromatic hydrocarbons in water samples, with relative recoveries in the range of 92.3-120%. The tube showed highest extraction ability for polycyclic aromatic hydrocarbons, higher extraction ability for hydrophobic phthalates and anilines, and almost no extraction ability for low hydrophobic phenols, due to the possible extraction mechanism including hydrophobic and electron-rich element-metal interactions.