Comparison of two polythiophene nanocomposites-based dispersive micro solid-phase extraction procedures coupled with salt-induced/magnetic separations for efficient preconcentration of toxic metal ions from food samples

Abstract For the first time, the polythiophene nanocomposite-based air-agitated dispersive micro solid-phase extraction coupled with salt-induced decantation is proposed for the preconcentration of the Pb(II) and Co(II) ions in the food samples. The nanoadsorbent was first synthesized via an in situ sonochemical oxidative polymerization method in the presence of FeCl3, as the oxidant, and other additives, including sodium dodecylbenzene sulfonate and ZnO nanoparticles (NPs). The use of an inorganic salt in the centrifugation step was influential on the separation of this highly soft nanocomposite. In the next step, the developed approach was statistically compared with the air-agitated magnetic micro solid-phase extraction method based on the same sorbent substrate but conjugated with magnetic NPs to retrieve the highly soft nanocomposite via magnetic forces. Under the optimal conditions, the two procedures provided comparable linear dynamic ranges with the correlation of determinations higher than 0.98. The detection limits obtained were satisfactory (8.0–10 ng mL−1 for the salt-induced dispersive solid-phase extraction and 0.7–1.5 ng mL−1 for magnetic assisted dispersive solid-phase extraction, respectively). The calculated enrichment factor values were approximately the same for the two procedures. In addition, the magnetic dispersive solid-phase extraction procedure enjoyed appropriate repeatability. These satisfactory validations satisfy the high efficiency of the salt-induced and magnetic procedures and the effectiveness of the used nanocomposites to establish versatile retention mechanisms without any crucial demand for the derivatization or complexing agents.