title: Innovative separation and preconcentration technique of coagulating homogenous dispersive micro solid phase extraction exploiting graphene oxide nanosheets.
abstract: A uniquely novel, fast, and facile technique is introduced for the first time in which a scant amount of graphene oxide (GO), without modification, has been utilized in dispersive mode of solid phase extraction (SPE) for an efficient yet simple separation. The proposed method of coagulating homogenous dispersive micro solid phase extraction (CHD-µSPE) is based on coagulation of homogeneous GO solution with the aid of polyetheneimine (PEI). CHD-µSPE use full adsorption capacity of GO because in this method was used GO solution obtained from synthesis process without drying step and stacking nanosheets. In optimized condition, 30 µL GO solution (7 mg mL(-1)), obtained in synthesis process, was injected into 1.5 mL the sample solution followed by immediate injection of 53 µL PEI solution (1 mg mL(-1)). After inserting PEI, GO sheets aggregate and can be readily separated by centrifugation. PEI not only cause aggregation of GO, but also form three-dimensional network of GO with easy handling in following separation steps. Lead, cadmium, and chromium were selected as model analytes and the effecting parameters including the amount of GO, concentration of PEI, sample pH, extraction time, and type of desorption solvent were investigated and optimized. The results indicate that the proposed CHD-µSPE method can be successfully applied GO in dispersive mode of SPE without effecting on good capability adsorption of GO. The novel method was applied in determination of lead, cadmium, and chromium in water, human saliva, and urine samples by electrothermal atomic absorption spectrometry. The detection limits are as low as 0.035, 0.005, and 0.012 µg L(-1) for Pb, Cd, and Cr respectively. The intra-day precisions (RSDs) were lower than 3.8%. CHD-µSPE method showed a good linear ranges of 0.24-15.6, 0.015-0.95 and 0.039-2.33 µg L(-1) for Pb, Cd and Cr respectively. Method performance was investigated by determination of mentioned metal ions in river water, human urine and saliva sample with good recoveries in range of 94.2-103.0%. The accuracy of the method was underpinned by correct analysis of a standard reference material (SRM: 2668 level I, Urine).
authors.affiliation: Department of Chemistry, College of Science, Semnan University, P.O. Box: 35131-19111, Semnan, Iran.
authors.forename: Mehri
authors.initials: M
authors.lastname: Ghazaghi
authors.affiliation: Department of Chemistry, College of Science, Semnan University, P.O. Box: 35131-19111, Semnan, Iran. Electronic address: hzmousavi@semnan.ac.ir.
authors.forename: Hassan Zavvar
authors.initials: HZ
authors.lastname: Mousavi
authors.affiliation: Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), West Entrance Blvd., Olympic Village, P.O. Box: 14857-33111, Tehran, Iran.
authors.forename: Ali Morad
authors.initials: AM
authors.lastname: Rashidi
authors.affiliation: Occupational and Environmental Health Research Center (OEHRC), Iranian Petroleum Industry Health Research Institute (IPIHRI), Tehran, Iran.
authors.forename: Hamid
authors.initials: H
authors.lastname: Shirkhanloo
authors.affiliation: Nanotechnology Research Center, Research Institute of Petroleum Industry (RIPI), West Entrance Blvd., Olympic Village, P.O. Box: 14857-33111, Tehran, Iran; Department of Research and Development, Sharif Ultrahigh Nanotechnologists (SUN) Company, P.O. Box: 13488-96394, Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Rahighi
mesh_terms: D006108:Graphite / Q000737:chemistry*; D049329:Nanostructures; D010087:Oxides / Q000737:chemistry*; D052617:Solid Phase Microextraction / Q000379:methods*
chemical_list: D010087:Oxides; D006108:Graphite
keywords: Cadmium; Chromium; Graphene oxide nanosheet; Homogenous dispersive micro solid phase extraction; Lead