Novel sol-gel titania-based hybrid organic-inorganic coatings for on-line capillary microextraction coupled to high-performance liquid chromatography

Publication Year:
2006
Usage 1456
Downloads 1249
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Repository URL:
https://scholarcommons.usf.edu/etd/2586
Author(s):
Kim, Tae-Young
Tags:
In-tube SPME; CME-HPLC; CME-GC; Gradient elution; Isocratic elution; Titania-PDMS; Titania-silica-TESP-PEO; PAHs; Ketones; Alkylbenzenes; Aldehydes; Anilines; Phenols; Fatty acids
thesis / dissertation description
Novel sol-gel titania-poly(dimethylsiloxane) (TiO2-PDMS) and titania-silica-N-(triethoxysilylpropyl)-O-polyethylene oxide urethane (TiO2-SiO2-TESP-PEO) coatings were developed for capillary microextraction (CME) to perform on-line preconcentration and HPLC analysis of trace impurities in aqueous samples. Due to chemical inertness of titania, effective covalent binding of a suitable organic ligand to its surface is difficult via conventional surface modification methods. In this research, sol-gel chemistry was employed to chemically bind hydroxy-terminated poly(dimethylsiloxane) (PDMS) and N-(triethoxysilylpropyl)-O-polyethylene oxide urethane (TESP-PEO) to sol-gel titania and sol-gel titania-silica network, respectively. A method is presented describing in situ preparation of the titania-based sol-gel PDMS and TESP-PEO coatings and their immobilization on the inner surface of a fused-silica microextraction capillary.To perform on-line CME-HPLC, the sol-gel TiO2-PDMS or TiO2-SiO2-TESP-PEO capillarywas installed in the HPLC injection port as an external sampling loop, and a conventionalHPLC separation column was used for the liquid chromatographic separation. The sol-gel TiO2-PDMS-coated microextraction capillary was used for on-line CME-HPLC analysis of non-polar and moderately polar analytes, and the sol-gel coatings showed excellent pH (1-13), and solvent (acetonitrile and methanol) stabilities under elevated temperatures (150 C) over analogous non-sol-gel silica-based coatings. Extraction of highly polar analytes, especially from aqueous phases is not an easy task. However, the sol-gel TiO2-SiO2-TESP-PEO-coated capillaries showed excellent capability of extracting underivatized highly polar analytes from aqueous samples.This opens the possibility to employ sol-gel titania-based polar coatings for solvent-free extraction and trace analysis of target analytes in environmental and biomedical matrices. To our knowledge, this is the first research on the use of sol-gel titania (or titania-silica)-based organic-inorganic materials as a sorbent in capillary microextraction. The newly developed sol-gel titania (or titania-silica)-based organic-inorganic hybrid extraction media provides an effective solution to coupling CME with HPLC (CME-HPLC), and this can be expected to become a powerful analytical tool in environmental investigations, proteomic research, early disease diagnosis and biomarker research. Being a combination of a highly efficient solvent free sample preconcentration technique (CME) and a powerful separation method (HPLC), CME-HPLC poses to become a key analytical tool in solving complex chemical, environmental, and biomedical problems involving complex matrices.