Polyanaline/SBA-15 nanocomposite for inside needle capillary microextraction

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Inside needle capillary microextraction (INCAT) is a promising solid phase microextraction (SPME) mode where the sorbent material is immobilized in the inner walls of a hollow stainless steel needle allowing the continuous sample flow through the extracting phase. Therefore, INCAT enhances the kinetic of the extractions and improves the preconcentration factors since larger sample volumes can be processed. Moreover, the extraction device is inexpensive, robust and it presents a higher mechanical stability compared to classic SPME fibers.

Although conventional SPME materials can be employed as extracting phases in INCAT, new materials have been developed in this context. Bagher at al. have already described, in a research article published in the Journal of Separation Science, a nanocomposite for the extraction of polycyclic aromatic hydrocarbons in water (1). The nanocomposite is based on the combination of hexagonally ordered silica (SBA-15) and polyaniline, each component playing a different role. On the one hand, SBA-15 which is used as inert support provides a high surface area (up to 1000 m2/g), porosity (pore size in the range from 5 to 30 nm) and thermal stability (up to 300ºC) while polyaniline allows the extraction of the target analytes by π-π and hydrophobic interactions.

The synthesis of the nanocomposite consists mainly on well defined steps. First of all, the SBA-15 support is prepared by a hydrothermal treatment using a triblock organic copolymer as template. After this treatment, the organic template is removed by calcination at 600ºC and the resulting solid is dispersed in an aqueous solution containing aniline which is finally polymerized by the addition of ammonium persulfate. As a result of this synthetic process, a nanocomposite in the form of nanometric particles is obtained. These particles are finally immobilized in the inner walls of the needle using epoxy glue.

In the article, the readers will find some interesting information concerning the synthetic process, the optimization of the extraction procedure and the analytical characterization of the proposed method.

 Reference
(1) Inside needle capillary adsorption trap device for headspace solid-phase dynamic extraction based on polyaniline/hexagonally ordered silica nanocomposite. Link to the article

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