Mercaptopropyl-functionalized nanoporous silica as a novel coating for solid-phase microextraction fibers

Abstract

In this study, nanoporous silica was functionalized with (3-mercaptopropyl)trimethoxysilane to obtain a high-efficiency fiber coating for solid-phase microextraction (SPME) of phenolic compounds. The new material was characterized by N₂ sorption, scanning electron microscopy and thermogravimetric analyses. The coated fiber was applied to the extraction of some phenolic and benzene, toluene, ethyl benzene and xylene (BTEX) compounds from aqueous solutions. It displayed some selectivity for the phenols and improved extraction efficiency in comparison to a commercial polydimethylsiloxane (PDMS) fiber. A simplex optimization of extraction temperature and time, ionic strength and sonication time led to an optimized protocol that gives relative standard deviations (exemplified for the extraction of phenols from spiked deionized water at 1.0 μg mL⁻¹ levels) between 6.1% and 8.9% (for n = 5). The detection limits are in the 1.0 to 11 ng mL⁻¹ range. The extraction efficiency is not significantly altered after 70 extractions and thermal desorptions. The fibers were successfully applied to the extraction and determination by gas chromatography-mass spectroscopy (GC-MS) of phenolic compounds in real samples.