| Title: | Sol-gel coating technology for the preparation of solid-phase microextraction fibers of enhanced thermal stability |
| Author(s): | Chong SL; Wang D; Hayes JD; Wilhite BW; Malik A; |
| Address: | "Department of Chemistry, University of South Florida, Tampa, Florida 33620-5250" |
| ISSN/ISBN: | 0003-2700 (Print) 0003-2700 (Linking) |
| Abstract: | "A novel sol-gel method is described for the preparation of solid-phase microextraction (SPME) fibers. The protective polyimide coating was removed from a 1-cm end segment of a 200 mum o.d. fused-silica fiber, and the exposed outer surface was coated with a bonded sol-gel layer of poly(dimethylsiloxane) (PDMS). The chemistry behind this coating technique is presented. Efficient SPME-GC analyses of polycyclic aromatic hydrocarbons, alkanes, aniline derivatives, alcohols, and phenolic compounds in dilute aqueous solutions were achieved using sol-gel-coated PDMS fibers. The extracted analytes were transferred to a GC injector using an in-house-designed SPME syringe that also allowed for easy change of SPME fibers. Electron microscopy experiments suggested a porous structure for the sol-gel coating with a thickness of approximately 10 mum. The coating porosity provided higher surface area and allowed for the use of thinner coatings (compared with 100-mum-thick coatings for conventional SPME fibers) to achieve acceptable stationary-phase loadings and sample capacities. Enhanced surface area of sol-gel coatings, in turn, provided efficient analyte extraction rates from solution. Experimental results on thermal stability of sol-gel PDMS fibers were compared with those for commercial 100-mum PDMS fibers. Our findings suggest that sol-gel PDMS fibers possess significantly higher thermal stability (>320 degrees C) than conventionally coated PDMS fibers that often start bleeding at 200 degrees C. This is due, in part, to the strong chemical bonding between the sol-gel-generated organic-inorganic composite coating and the silica surface. Enhanced thermal stability allowed the use of higher injection port temperatures for efficient desorption of less-volatile analytes and should translate into extended range of analytes that can be handled by SPME-GC techniques. Experimental evidence is provided that supports the operational advantages of sol-gel coatings in SPME-GC analysis" |
| Notes: | "PubMed-not-MEDLINEChong, S L Wang, D Hayes, J D Wilhite, B W Malik, A eng 1997/10/01 Anal Chem. 1997 Oct 1; 69(19):3889-98. doi: 10.1021/ac9703360" |
