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Abstract
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In this research a novel nanocomposite based on incorporation of montmorillonite
(MMT) [1,2] into polyaniline-polyamide (PA) hybrid was prepared by in situ oxidative
polymerization of polyaniline (PANI) into MMT/PA mixture and subsequently solvent
exchange method to obtain a thin layer onto stir bar substrate. The morphology and surface
characteristic of PA and MMT/PANI/PA coated stir bars were investigated using scanning
electron microscopy (SEM), energy dispersive X-ray spectroscomy (EDX), X-ray diffraction
(XRD) and Fourier transform infrared sepectroscopy (FTIR). The prepared MMT/PANI/PA
nanocomposite-based stir bar was applied as an extraction device for stir bar sorptive
extraction (SBSE) [3] of organophosphorous pesticides (OPPs) in some fruit juices and
vegetables in combination with gas chromatography-flame ionization detector (GC-FID)
detection. The effect of MMT amount in the nanocomposite and also the effect of PANI
incorporation into PA on the extraction capability of the coating was investigated. Important
factors influencing the extraction and desorption processes including extraction time, salt
content, pH, desorption solvent, its volume and desorption time were studied and optimized
using response surface methodology (RSM) applying central composite design (CCD) [4].
Limit of detection (LOD) and linear dynamic range (LDR) of the method were in the range of
0.2 to 1 ng mL 1 and 0.6-1000 and 3-1000 ng mL-1, respectively. The method precision (RSD
%) with four replicates determinations was in the range of 2.5 to 4.4 % for distilled water at
the concentration level of 100 ng mL 1. The developed method was successfully applied to
the various fruit juices and vegetable samples, while the relative recoveries (RR%) were
obtained to be in the range of 80.0 to 99.7%.
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