Flame atomic absorption spectrometric determination of Cu and Ni in tobacco samples after Preconcentration using ammonium pyrrolidine dithiocarbamate modified magnetic nanoparticles

Fe3O4 nanoparticles coated with SiO2 and modified with ammonium pyrrolidine dithiocarbamate as a new adsorbent for the single-step extraction and preconcentration of trace amounts of copper and nickel from tobacco samples were prepared. The particle sizes of nanoparticles were characterised by transmission electron microscope. Several parameters affecting the analytical performance, such as the amount of ammonium pyrrolidine dithiocarbamate, amount of magnetic nanoparticles, pH, contact time, coexisting ions, desorption solution and reuse times of magnetic solid-phase extraction, were discussed and optimised. The analytes desorbed from magnetic nanoparticles were determined by flame atomic absorption spectrometry. Under the optimum conditions, the analytical linear ranges were 0.02-15mg/L for Cu and 0.02-20mg/L for Ni (R-2>0.9992). The relative standard deviations (RSDs, n=5) of 1.8% and 2.1% were obtained for Cu and Ni, respectively. The method detection limits were 0.0028 g/g for Cu and 0.0037 g/g for Ni. The proposed method was successfully applied to tobacco sample analysis and got excellent recoveries in the range of 89.6-102.3% and RSDs (n=5) of 1.2-2.5%. This method is much faster and more effective than traditional methods, and it is promising for the analysis of heavy metals.