Montmorillonite/polyaniline/polyamide nanocomposite as a novel stir bar coating for sorptive extraction of organophosphorous pesticides in fruit juices and vegetables applying response surface methodology

Abstract

In this research a novel nanocomposite based on incorporation of montmorillonite (MMT) into a polyaniline–polyamide (PANI–PA) hybrid was prepared by in situ oxidative polymerization of polyaniline in the MMT–PA mixture and subsequently solvent exchange method was used to obtain a thin layer onto a stir bar substrate. The prepared nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The prepared MMT/PANI/PA nanocomposite-based stir bar was applied as an extraction device for stir bar sorptive extraction (SBSE) of organophosphorous pesticides (OPPs) in some fruit juices and vegetables in combination with gas chromatography-flame ionization detector (GC-FID) detection. The effect of the MMT amount in the nanocomposite and also the effect of PANI hybridization on the extraction capability of the coating were 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). The 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 replicate 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 found to be in the range of 80.0 to 99.7%.