Electrospun Fibers for Solid-Phase Microextraction

A method of producing solid-phase microextraction (SPME) fibers based on electrospinning polymers into nanofibrous mats is demonstrated. Using this method the polymer mat is attached to a stainless steel wire without the need of a binder. While applicable to any polymer that can be electrospun, a polymeric negative photoresist, SU-8 2100, is used for this initial study. SPME devices composed of carbon nanofibers are also illustrated by pyrolyzing SU-8 to produce amorphous carbon. Nonpolar compounds, benzene, toluene, ethylbenzene, and o-xylene (BTEX) and polar compounds, phenol, 4-chlorophenol and 4-nitrophenol are extracted under headspace SPME conditions. Extraction efficiencies are compared to commercial polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), and polyacrylate (PA) fibers. For both the nonpolar and polar compounds, the carbon nanofiber based phases demonstrated enhanced or comparable (o-xylene only) extraction efficiencies. Distribution constants, K, for benzene on the electrospun fibers are of greater or similar magnitude to those of the compared commercial fibers and increase with carbonization temperature. Finally, the measured detection limits for all the organic compounds are similar to those measured with other SPME gas chromatography-flame ionization detector (GC-FID) methods with a large linear dynamic range (3 orders of magnitude) for quantification.