Molecularly imprinted solid-phase extraction method based on SH-Au modified silica gel for the detection of six Sudan dyes in chili powder samples.

In this research, the successfully developed molecularly imprinted solid-phase extraction (MISPE) method based on SH-Au modified silica gel for Sudan dyes determination has been described. Gold nanoparticles (Au NPs) were organized onto the surface of silica gel through the covalent binding between sulfydryl and Au. Subsequently, molecularly imprinted polymers (MIPs) were prepared via the graft polymerization using Au NPs as the functional monomer. The composition and morphology of MIPs were characterized by X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TG). Binding property was systematically evaluated through adsorption isotherm, adsorption kinetics, and selective recognition capacity. MISPE pretreatment was successfully established after optimizing various parameters. Under optimized conditions, good linearity for six investigated Sudan dyes was ranged from 0.005 to 10.0μgg (R>0.999) with low limits of detection and quantification (1.5-4.7 and 5.2-15.5ngg, respectively). The recoveries at three different spiked levels (0.05, 0.5, and 2.0μgg of each Sudan dye) were ranged from 87.2% to 94.7% with RSD below 6.1% (n=3). The results demonstrated one reliable, sensitive and accurate MISPE pretreatment technique with excellent reproducibility for the determination of six Sudan dyes in chili powder samples.