title: In situ hydrothermal grown silicalite-1 coating for solid-phase microextraction.
abstract: A novel fiber coated with silicalite-1 for solid-phase microextraction (SPME) was prepared by in situ hydrothermal growth method. Six substituted benzenes (nitrobenzene, p-dichlorobenzene, m-dichlorobenzene, 1,3,5-trichlorobenzene, p-chloronitrobenzene, and m-chloronitrobenzene) were employed as model analytes. The fiber exhibited high thermal stability (little weight loss up to 600 °C) and high chemical stability (no loss of function after sequential immersion in 0.1 M HCl, 0.01 M NaOH, methanol, and n-hexane each for at least 4 h). Compared with commercial fibers, 3-6 times higher extraction efficiencies were shown on the fiber for mono- and p-substituted benzenes. Under the preoptimized conditions, the fiber afforded satisfactory enhancement factors (517-1292), wide linear ranges (more than 2 orders of magnitude), low limits of detection (0.001-0.130 μg/L), and acceptable repeatability (<9.6%) and reproducibility (<8.8%). Furthermore, the fiber offered distinct shape-selectivity attributed to the uniform molecular-scale pore structure of silicalite-1. The ratios of extraction were approximately 70 between p-dichlorobenzene and 1,3,5-trichlorobenzene, 30 between p-chloronitrobenzene and m-chloronitrobenzene, and 3 between p-dichlorobenzene and m-dichlorobenzene. After pore narrowing by surface modification with SiCl(4), the selectivity for p-dichlorobenzene over m-dichlorobenzene was further enhanced by another 10 times. Finally, the fiber was successfully applied to analysis of a real water sample.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse/School of the Environment, Nanjing University, Jiangsu 210093, China.
authors.forename: Heyun
authors.initials: H
authors.lastname: Fu
authors.forename: Dongqiang
authors.initials: D
authors.lastname: Zhu