RESUMO
In the present work, methyl red molecularly imprinted polymeric (MR-MIP) nanostructure was synthesized using the precipitation polymerizations for the separation of MR dye from aqueous media. The as-prepared MIP was characterized using colorimetry, infrared (IR) spectroscopy, and scanning electron microscopy (SEM). In addition, vortex-assisted dispersive micro-solid phase extraction (VAD-µSPE) based on MIP nanostructure was accomplished as a simple and efficient method for selective preconcentration of low amounts of MR from aqueous solutions. The effects of important parameters such as pH, adsorbent dose, eluent volume, and vortex adsorption-desorption time on the extraction efficiency were investigated. Two techniques including UV-Vis absorption spectroscopy and solution scanometry were applied for the analysis of MR content, comparatively. In spectrophotometric determination, the highest recovery was observed at pH 3.5 after 5 and 3 min of vortex time in the adsorption and desorption steps. The preconcentration factor of 75 and a wide linear concentration range (0.010 and 2.0 mg.L-1; R2 = 0.996) and low detection limit (LOD = 5.0 µg.L-1) with an acceptable precision (RSD = 3.4 %) was observed, too. Under optimum conditions in scanometric determination, a high preconcentration factor (i.e. 500) and similar linearity (0.010-2.0 mg.L-1; R2 = 0.989) and a low LOD of 3.1 µg.L-1, with the relative standard deviation of 1.4% was observed. Both techniques were used for MR recovery from various aqueous samples, successfully.