Magnetic solid-phase extraction technique based on Fe3O4@coPPy-PTH nanocomposite for extraction of cobalt, chromium, and nickel prior to determination by micro-sample injection system-flame atomic absorption spectrometry in alcoholic and nonalcoholic beverages

A novel Fe3O4@coPPy-PTH nanocomposite-based sorbent was prepared via in-situ oxidative polymerization using Fe3O4 nanoparticles with spherical and flower-like morphologies of thiophene and pyrrole as the feedstocks. The synthesized nanocomposite utilized sensitive extraction and determination of the metal ions Co(II), Cr(III), and Ni(II) without a chelating agent, followed by a micro-sample injection system-flame atomic absorption spectrometer (MIS-FAAS). The composition and morphology of Fe3O4@coPPy-PTH nanocomposite were characterized by advanced spectroscopic and imaging techniques like SEM and FT-IR. SEM observations showed the size of Fe3O4 nanoparticles changed from 30 nm to 120 nm in diameter after the copolymer (PPy-PTH) coating. The Fe3O4@coPPy-PTH nanocomposite possesses good dispersion properties and acid stability in strong acid solutions. For effective extraction of studied analytes, the influence of sample pH, volume of sample solution and eluent, amount of adsorbent, and interference of coexisting metal ions were optimized. Under the optimum conditions, preconcentration factors were obtained to be 25 for all analytes. The calibration curves were linear in the range of 0.0-10.0 mu g L-1 with coefficients of determination (R-2) more than 0.9957 for all three analytes. Limits of detection (S/N=3) were calculated in the range of 0.17-0.23 mu g L-1. Precisions, expressed as relative standard deviations (RSD), were lower than 3.0 %, and relative recoveries were obtained in the range of 88.6-103.6 %. The proposed method (Fe3O4@coPPy-PTH/MSPE/MIS-FAAS) was successfully applied to extract and determine studied metal ions in beer, wine, and nonalcoholic beverage samples.