Electrospinning composites of polyvinylidene fluoride - carbon black on solid phase microextraction fibers for enhanced detection of volatile organic compounds by gas chromatography-mass spectrometry

Abstract

Urine contains volatile organic compounds (VOCs) that can be a source of biomarkers for different medical conditions. Headspace solid phase microextraction (HS-SPME) gas chromatography-mass spectrometry (GC–MS) is the gold standard for VOC detection but is time-consuming and expensive. Gas sensors on the other hand are portable and provide rapid results, but qualification of sensing layers is tedious as VOCs need to be tested individually. Our previous study showed that dip coating SPME fibers, using them to extract VOCs from urine and analyzing them by GC–MS is a tool to rapidly characterize sensing elements. The current study aims to extend these findings to demonstrate that HS-SPME GC–MS can identify how electrospinning can enhance the detection of VOCs due to the increased surface area. Herein, previously optimized suspensions of polyvinylidene fluoride-carbon black (PVDF-CB) were deposited on SPME fiber substrates through dip coating and electrospinning, used to extract VOCs from urine and were subject to GC–MS. Electrospinning parameters (applied voltage, flow rate and duration) were optimized, which showed that an applied voltage of 17 kV and a flow rate of 0.25 mL/hr was optimal for electrospinning fibers with 1.5 µm diameter, high coverage and little to no beading. SPME fibers electrospun with PVDF-CB for 10 min were compared to dip coated fibers, and the results showed electrospun fibers had increased efficiency to extract an abundant number of VOCs in urine. These VOCs were enriched when sampled by the electrospun fiber by factors ranging from 1.5 – 5.5. Results also showed that the electrospun fibers had significantly higher reproducibility (p-value < 0.001) relative to dip coated fibers. In summary, electrospinning has the capability of fabricating more sensitive SPME fibers relative to dip coating, and therefore may be utilized in the future for an array of different applications including but not limited to VOC biomarker discovery.

Keywords

• Volatile organic compounds (VOCs)
• Solid phase microextraction (SPME)
• Gas chromatography-mass spectrometry (GC-MS)
• Electrospinning