Preparation of Solid Phase Microextraction (SPME) Probes through Polyaniline Multiwalled Carbon Nanotubes (PANI/MWCNTs) Coating for the Extraction of Palmitic Acid and Oleic Acid in Organic Solvents

A fiber coating from polyaniline (PANI) was electrochemically prepared and employed for Solid phase micreoextraction (SPME). The PANI film was directly electrodeposited on the platinum wire surface using cyclic voltametry (CV) technique. The same method was applied for the preparation of SPME fiber coated by polyaniline multiwalled carbon nanotubes (PANI/MWCNTs) composite. The concentration of sulfuric acid for electropolymerization was 0.1 M in the presence of 0.045 M aniline in aqueous solution. For the electrodeposition of PANI/MWCNT composite, 4 μg/mL of MWCNTs was dispersed into the solution. Film coating was carried out on the platinum wire by repetitive cycling of potentials between 0 and 1.0 V at the scan rate of 0.05 V/s. The applicability of these coatings were assessed through employing a laboratory-made SPME injecting device and gas chromatography with mass spectrometry (GC-MS) for the extraction of palmitic acid and oleic acid from chloroform. The developed method proved to be simple and easy, offering high reproducibility. Both PANI coated and PANI/CNT coated probes had the ability to concentrate palmitic acid and oleic acid on their coating and produced strong signals in GC-MS chromatograms. In the meantime, PANI/CNT coated SPME probes produced signals which were stronger than those produced by PANI coated SPME probes. The amount of extracted palmitic acid and oleic acid from chloroform by the PANI/MWCNTs coating was about 6 and 12 times higher than the amount extracted by plane PANI SPME fibers respectively. It could be suggested that the composite material with CNTs has both an increased surface area and an elevated absorptive capacity which leads to this overall increase in extracted palmitic acid and oleic acid.