Electrospinning preparation of solid phase microextraction fibers based on polyamide

By R. Lucena -

Polymeric nanofibers present high surface-to-volume ratios which make them so attractive in extraction procedures since their high superficial area increases the potential interaction analyte-sorbent with positive thermodynamic and kinetic connotations. The synthesis and preparation of these nanofibers can be achieved in the lab by electrospinning. This process is based on the application of a high voltage to a polymer solution in order to produce a thin liquid jet which is finally ejected.

First of all, a precursor of the nanofiber polymer is dissolved in an appropriate solvent to produce a viscose solution which is introduced in a syringe for its dispensation at a fixed and controlled velocity. Later on, an electric field (high voltage) is established between the syringe needle and a collector which acts also as the receptor of the produced nanofibers. As a consequence of this electric field, the mutual charge repulsion on the surface of the liquid overcomes the surface tension and causes an ejection of the precursor in the form of a liquid jet. The readers can found an animation that explains the electrospinning process in the webpage of the Michigan Technological University. (animation)

Bagheri et al have recently proposed a similar approach to produce polyamide nanofibers which are finally used as sorptive phase in the solid phase microextraction (SPME) of some chlorophenols. The procedure followed by the authors in order to construct the SPME coating is very similar to that previously described but in this case the end-tip of a SPME fiber is employed as collector. In order to produce an homogeneous coating, the end-tip is rotated at 55 rpm during the application of the external electric field. The nanofibers produced presents diameters in the range of 100-200 nm with spaces between nanofibers of 200-500 nm. This final aspect is so interesting to allow the transference of the analytes through the nanofibers mat. Moreover, the sorptive material is thermostable allowing the thermal desorption of the analytes.

Link to the article: Novel polyamide-based nanofibers prepared by electrospinning technique for headspace solid-phase microextraction of phenol and chlorophenols from environmental samples.

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