In-needle Microextraction Coupled with Gas Chromatography/Mass Spectrometry for the Analysis of Phthalates Generating from Food Containers

In this study, we fabricated a new device for headspace in-needle microextraction using a stainless steel wire coated with multiwalled carbon nanotube/polyaniline composite by coulometric technique. Then, the coated wire was placed into a stainless steel needle inside. This headspace in-needle microextraction device was applied for the determination of phthalates dissolved in aqueous solution by gas chromatography-mass spectrometry. Multiwalled carbon nanotube/polyaniline composite film of 10 mm length on the surface of stainless steel wire was optimized to polymerize electrochemically when constant potential of 2.0 V was applied during 500 s. Atomic force microscopy and Auger electron spectroscopy showed that polymerization on the surface of wire had smooth, homogeneous, and constant coating thickness of 1.5 ± 0.004 μm. The optimum molar ratio of multiwalled carbon nanotube and aniline (C:N) for polymerization was determined at 1: 2 M ratio. The optimum conditions of the proposed method were extraction temperature 50 °C, saturation time 60 min, extraction time 30 min, desorption temperature 230 °C, and desorption time 3 min, respectively. Validation of headspace in-needle microextraction-multiwalled carbon nanotube/polyaniline coupled with GC/MS was also performed including limit of detection, limit of quantitation, dynamic range, recovery, and reproducibility. The proposed device is found to be inexpensive, easy, and rapid to fabricate and could be utilized effectively as the solventless microextraction method for the analysis of phthalates generating from food containers.