Abstract
We report the first fabrication of sputtered carbon, solid-phase microextraction (SPME) fibers. These fibers have competitive extraction capabilities compared with the commercial carbon wide range (CWR) SPME fiber. This report also includes a demonstration of a newly developed SPME test mix that includes 15 different compounds with a wide range of functional groups and chemical properties. The fiber fabrication process involves sputtering carbon onto fused silica fibers, and the effects of throw distance on the morphology of the carbon coatings were studied. Four different carbon coating thicknesses were evaluated, with PDMS added as a stationary phase. These fibers were characterized with multiple analytical techniques, including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), water contact angle (WCA) goniometry, as well as headspace (HS) and direct immersion (DI)–SPME–GC–MS. The best (11.5 µm) sputtered carbon SPME fibers, with and without PDMS, were evaluated using the new evaluation mix and compared with the commercial CWR fiber and a previously sputtered/developed silicon fiber. The new probe mix helped elucidate differences among the fibers, which would have been missed by current commercial test mixes. The sputtered carbon SPME fibers showed similar functional group selectivity as commercial CWR fibers. However, the sputtered carbon fibers showed higher responses per volume compared with the commercial CWR fiber, indicating the porous morphology of the sputtered carbon has the ability to overcome large phase thickness/volume discrepancies and increase the relative recovery for various compounds.
Highlights
Solid-phase microextraction (SPME) is a green, solventless sampling technique that has grown rapidly since its introduction by Arthur and Pawliszyn [1]
scanning electron microscopy (SEM) was used to characterize the surface morphology of the sputtered carbon coatings that were deposited at three different throw distances (4, 12, 20 cm)
Coatings produced at the 4 cm throw distance were more porous than the other two. We attribute this substantial difference in morphology to the directionality of the sputtering process
Summary
Solid-phase microextraction (SPME) is a green, solventless sampling technique that has grown rapidly since its introduction by Arthur and Pawliszyn [1]. SPME requires little to no sample preparation and allows for high throughput and automated analysis via robotics. It is commonly used in tandem with gas chromatography (GC) and liquid chromatography (LC). SPME is a remarkable tool that is widely accepted by the scientific community. It is used in environmental [2], pharmaceutical [3], biological [4], forensic [5], food [6], and natural product analyses [7]. There are different commercial coatings available, e.g., polydimethylsiloxane (PDMS), polyacrylate (PA), carboxen/polydimethylsiloxane (CAR/PDMS), and PDMS/divinylbenzene (DVB). These commercial fibers suffer from various drawbacks. The fibers and coatings may be fragile, weakly adhered to each other, or show poor thermal stability, short lifetimes, high carry-over, and high phase bleed [8]
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