Gradient extractive phase prepared by controlled rate infusion
method: An applicable approach in solid phase icroextraction for
non–targeted analysis
Marzieh Enteshari Najafabadi, Elaheh Kazemi, Habib Bagheri
Journal of Chromatography A, 1574 (2018) 130-135
doi: 10.1016/j.chroma.2018.09.001
The aim of this study is to introduce an extractive phase based on gradient concept by continuous changing
in chemical functional groups for non–targeted analysis. For this purpose, three different two–component
coatings containing (3–aminopropyl)trimethoxysilane (APTES) as polar and either phenyltriethoxysilane
(PTES), octyl–trimethoxysilane (OTMS) or methyltrimethoxysilane (MTMS) as nonpolar precursors were
formed on the modified stainless steel wires using controlled rate infusion (CRI) method. The presence of
polar and/or non–polar functional groups on the surface of substrate was evaluated by Fourier–transform
infrared spectroscopy (FTIR) together with contact angles determined alongside the gradient surface. The
morphology and thickness of the prepared fibers were also investigated by scanning electron microscopy
(SEM). Furthermore, uniform single–component fibers from polar (APTES) and nonpolar (PTES) coatings
were fabricated in order to be compared with the gradient sorbent. The gradient phase was implemented
as a fiber coating in headspace– or immersed–solid phase microextraction of various compounds including chlorobenzenes, polycyclic aromatic hydrocarbons, chlorophenols and volatile organic compounds
(Log Kow range: -0.77 to 4.64). Under the optimized condition, the limits of detection and quantification were obtained in the range of 0.01–0.5 µg L-1 and 0.05–1.5 µg L-1, respectively. The intra–day and
inter–day relative standard deviations of 2–10% and 11–17% were achieved, respectively. The method
was successfully applied to the extraction of VOCs from real water sample and relative recoveries were
between 89 and 105%. The capability and efficiency of the gradient coating appears to be quite appropriate
for non–targeted analysis.