A silica aerogel as an extractive coating for in-tube solid-phase microextraction to determine polycyclic aromatic hydrocarbons in water samples

Silica aerogel with high surface area was prepared by an acid-base two-step catalytic sol-gel method under ambient pressure drying. It was coated onto stainless steel wires as an extraction phase, then three wires were placed into a polyetheretherketone tube for forming an in-tube solid-phase microextraction device. Combined with high performance liquid chromatography, the extraction device was assessed and it exhibited better extraction ability for polycyclic aromatic hydrocarbons than for estrogens and phthalates. Eight polycyclic aromatic hydrocarbons were selected as model analytes, and four main factors including sampling volume, sampling rate, organic solvent content in the sample and desorption time were investigated to achieve high sensitivity. After that, an on-line analysis method was established with low limits of detection (0.005-0.050 mu g L-1), low limits of quantitation (0.017-0.165 mu g L-1), wide linear range (0.017-15 mu g L-1), good correlation coefficients (0.9990-0.9998) and high enrichment factors (576-2245). Relative standard deviations of the intra-day test and inter-day test were separately less than 2.0% (n = 3) and 3.6% (n = 3), demonstrating the stable performance of the extraction device. During the investigation of durability and chemical stability, relative standard deviations less than 7.8% (n = 3) indicated that the extraction device had satisfactory reusability under harsh conditions. Finally, the analytical method was successfully applied to the detection of polycyclic aromatic hydrocarbons in real water samples.