Synthesis of polyaniline-coated titanium oxide nanoparticles for preconcentration of cobalt (II) followed by electrothermal atomic absorption spectrometry

An efficient and novel adsorbent, polyaniline (PANI)-coated titanium oxide nanoparticle (TiO 2 -NPs) was applied for preconcentration of ultra-trace levels of Co 2+ followed by electrothermal atomic absorption spectrometry. In this method, TiO 2 -PANI nanoparticles were synthesized by chemical method and used as an adsorbent in solid phase extraction. The scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectrophotometry were applied to characterize of the synthesized TiO 2 -PANI nanoparticles. The parameters affecting the extraction recovery including amounts of adsorbent (g), sample solution pH, and extraction and desorption time (min) were optimized by the response surface methodology based on central composite design. The optimum conditions obtained at the pH of 9.0, 10.0 mg amounts of TiO 2 -PANI nanoparticles, 10.0 min extraction time and 3.50 min desorption time. Also, the linear range of the calibration curve was obtained at 0.10–2.0 µg L −1 Co 2+ with a correlation coefficient of 0.9976. The relative standard deviation (RSD, %) was 3.7% for the six times replicate analysis of 0.50 µg L −1 of Co 2+ and the limit of detection (LOD) was 0.036 µg L −1 ( n = 8). The method’s accuracy was checked by analyzing of the certified reference material and finally, the proposed method was used for the preconcentration and determination of Co 2+ in different food and water samples.