We describe a new process for preparing porous solid phase microextraction (SPME) coatings by the sputtering of silicon onto silica fibers. The microstructure of these coatings is a function of the substrate geometry and mean free path of the silicon atoms, and the coating thickness is controlled by the sputtering time. Sputtered silicon structures on silica fibers were treated with piranha solution (a mixture of concd H₂SO₄ and 30% H₂O₂) to increase the concentration of silanol groups on their surfaces, and the nanostructures were silanized with octadecyldimethylmethoxysilane in the gas phase. The attachment of this hydrophobic ligand was confirmed by X-ray photoelectron spectroscopy and contact angle goniometry on model, planar silicon substrates. Sputtered silicon coatings adhered strongly to their surfaces, as they were able to pass the Scotch tape adhesion test. The extraction time and temperature for headspace extraction of mixtures of alkanes and alcohols on the sputtered fibers were optimized (5 min and 40 °C), and the extraction performances of SPME fibers with 1.0 or 2.0 μm of sputtered silicon were compared to those from a commercial 7 μm poly(dimethylsiloxane) (PDMS) fiber. For mixtures of alcohols, aldehydes, amines, and esters, the 2.0 μm sputtered silicon fiber yielded signals that were 3–9, 3–5, 2.5–4.5, and 1.5–2 times higher, respectively, than those of the commercial fiber. For the heavier alkanes (undecane–hexadecane), the 2.0 μm sputtered fiber yielded signals that were approximately 1.0–1.5 times higher than the commercial fiber. The sputtered fibers extracted low molecular weight analytes that were not detectable with the commercial fiber. The selectivity of the sputtered fibers appears to favor analytes that have both a hydrophobic component and hydrogen-bonding capabilities. No detectable carryover between runs was noted for the sputtered fibers. The repeatability (RSD%) for a fiber (n = 3) was less than 10% for all analytes tested, and the between-fiber reproducibility (n = 3) was 0–15%, generally 5–10%, for all analytes tested. The repeatabilities of our sputtered fibers and the commercial 7 μm PDMS fiber are essentially the same. Fibers could be used for at least 300 extractions without loss of performance. More than 50 compounds were identified in a gas chromatography–mass spectrometry headspace analysis of a real world botanical sample with the 2.0 μm fiber.

Item Type:	Refereed Article
Keywords:	coatings, solid phase microextraction, sputtering, gas chromatography
Research Division:	Chemical Sciences
Research Group:	Analytical Chemistry
Research Field:	Separation Science
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Chemical Sciences
Author:	Yan, DD (Ms Dandan Yan)
Author:	Tedone, L (Ms Laura Tedone)
Author:	Nesterenko, PN (Professor Pavel Nesterenko)
Author:	Paull, B (Professor Brett Paull)
Author:	Shellie, RA (Associate Professor Robert Shellie)
ID Code:	106835
Year Published:	2016
Web of Science® Times Cited:	5
Deposited By:	Chemistry
Deposited On:	2016-02-23
Last Modified:	2017-10-30
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