Novel Schiff base-functionalized metal-organic framework nanoparticles for dispersive solid phase extraction of copper ions from vegetable and water samples

In this study, a novel method for the extraction of Cu(II) using ligand-functionalized MOF nanoparticles is described. The synthesized nanoparticles were characterized by FTIR, XRD, SEM and EDX methods. The analytical procedure is based on ligand@MIL-101(Cr) NPs as a sorbent which were added to an aqueous solution containing Cu(II), and the mixture was allowed to equilibrate for 30 min at room temperature. When the suspension became limpid, the supernatant was poured off, and the isolated ligand@MIL-101 NPs were eluted with HCl (1 M) to desorb the preconcentrated Cu(II) ions. The eluted solution was collected and analyzed with FAAS. Effective parameters were studied and optimized to achieve the best extraction and preconcentration efficiency of this method. The optimum conditions for extraction of 200 mL of water sample include 30 mg of modified nanoparticles as the sorbent, 30 min extraction time, 7 min centrifuge time with 9000 rpm, 2 mL HCl (1 M) as the desorption solvent and 8 min desorption time. Under the optimum conditions, the limits of detection (LOD) and quantification (LOQ) for Cu(II) were 0.47 and 1.56 ng mL(-1), respectively. The preconcentration factor and RSD for five replicates of Cu(II) were calculated to be 94 and 3.04%, respectively. The nanoparticles showed excellent performances in the removal and preconcentration of Cu(II) from aqueous solutions. Finally, the applicability of this method was studied by the extraction and determination of Cu(II) in vegetable and environmental water samples with recovery percentages of 92-98%.