Simultaneous solid-phase extraction of Cu imprinted polymer based on Graphene oxide

Microwave-assisted double template ion-imprinted polymer (MA/Fe.sub.3O.sub.4@GO@Cd/Cu-IIP) based on magnetic graphene oxide was prepared for the extraction of Cd(II) and Cu(II) from celery extract. The synthesis of MA/Fe.sub.3O.sub.4@GO@Cd/Cu-IIP adopted inverse emulsion-suspension polymerization using Cu(II) and Cd(II) as double template ions, acrylamide as functional monomer and Fe.sub.3O.sub.4@GO as carrier. The morphology, structure and thermal stability of MA/Fe.sub.3O.sub.4@GO@Cd/Cu-IIP were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), fourier transmission infrared spectrometer (FTIR), X-ray diffraction (XRD), thermogravimetric (TG) and elemental analysis. The whole adsorption process followed pseudo-second-order kinetic, intra-particle diffusion and Langmuir isotherm models. High affinity sites and low affinity sites existed on IIP according to the Scatchard model. MA/Fe.sub.3O.sub.4@GO@Cd/Cu-IIP was successfully used as a solid phase extraction (SPE) sorbent combined with HPLC to recognize and extract Cd(II) and Cu(II) specifically in celery extract within a linear range of 0-500 [mu]g·L.sup.-1. The optimization conditions of the SPE included the concentration of eluent, the volume of celery extract, pH value and ionic strength. The solid phase extraction efficiency improved with the increase of ionic strength and still maintained a high level without the interference of competing ions. The SPE efficiency could still achieve 86.3% for Cd(II) and 98.5% for Cu(II) after 5 reuses. Results showed that the low detection limits (LOD) for Cu(II) and Cd(II) were 0.88 [mu]g·L.sup.-1-1.95 [mu]g·L.sup.-1 and 0.021 [mu]g·L.sup.-1-0.069 [mu]g·L.sup.-1, respectively. MA/Fe.sub.3O.sub.4@GO@Cd/Cu-IIP could be widely utilized for enrichment and determination of Cd(II) and Cu (II) in the extracts of celery, potato, pleurotus ostreatus, rape, tomato, lettuce, chives and shiitake.