Modified Magnetic Nanocomposites with 2-Aminobenzothiazole as a Selective Adsorbent for Dispersive Magnetic Micro-solid Phase Extraction of Ultra-trace Amounts of Cadmium in Environmental and Food Samples by Thermospray Flame Furnace Atomic Absorption Spectrometry

This study reports for the first time the synthesis and analytical performance of two novel magnetic nanocomposites-based silica-coated and carbon nanotubes thiol (2-aminobenzothiazole – ABT) functionalized as adsorbents for preconcentration of cadmium ions in water, cigarette and food samples by dispersive magnetic micro-solid phase extraction (DM-µ-SPE) and determination by thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS). The synthesized materials were characterized by Fourier infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), nitrogen adsorption–desorption, and thermogravimetric analysis (TGA). The pH was investigated univariately while other parameters that influence the DM-µ-SPE were investigated using a two-level (24) full factorial design. As optimized conditions, pH 7.0 and 6.0; 20 mg of nanoparticles; HNO3 1.5 M as eluent and 2 min and 8 min as elution time, were found to m-SiO2-ABT and MMWCNT-ABT, respectively. The method also showed good linearity in the range of 1.0 to 10.0 µg L−1 (r2 ≥ 0.99) and of 2.0 to 20.0 µg L−1 (r2 ≥ 0.99), and low limits of detection (0.02 and 0.11 µg L−1) to m-SiO2-ABT and MMWCNT-ABT, respectively. The nanocomposites, m-SiO2-ABT and MMWCNT-ABT, can be regenerated without significant adsorption capacity loss for ten cycles, yielding recovery percentages of analytical signal of 93.04% and of 103.2%, respectively. The analysis of different water samples (tap water and mineral water), tobacco, green tea, and rice was carried out without matrix interference, yielding recovery values ranging from 88 to 104%.