Application Of Graphene Solid-phase Extraction Combined With Atomic Absorption Spectrometry For Determination Of Several Trace Metal Elements

As a very dynamic branch of separation science, solid-phase extraction (SPE) is widelyused in the fields of environmental, pharmaceutical, clinical, food and chemitry, etc. In thestudy of the solid-phase extraction technology, it is found that the adsorption material usedis an important factor affectting the analytical sensitivity and selectivity. So looking fornew adsorbent material with superior performance has always been a hot research topic.In2004, Novoselov and Geim group in University of Manchester firstly discovered anew nanomaterial called graphene. Due to its excellent mechanical, electrical, optical andthermal properties, it has gained widespread concern in chemical, electronics, information,energy, materials and bio-medicine and other research areas. Graphene is the name given toa flat monolayer of carbon atoms with hexagonal cell tightly packed into atwo-dimensional (2D) honeycomb lattice, and is considered to be a basic building block ofcarbon allotropes including graphite, carbon nanotubes (CNTs), fullerene (C60) and so on.Successful preparation of single-layer graphene has triggered a new round of researchupsurge.However, there are not so many studies using graphene as adsorbent material forseparation and enrichment in solid-phase extraction currently. Moreover, it was mainlyapplied in the study of the adsorption for organic compounds in environmental samples,few studies focusing on the adsorption of metal ions. This study successfully synthesizedgraphene nanomaterials, and used it as column packing of solid phase extraction. Adetailed examination on adsorption performance for trace metal ions of the grapheneobtained was carried out and the column prepared was applied in quantiative detection oftrace metal elements.The first part of this paper described the principle of solid phase extraction technologyand summarized the applications of different types of solid-phase extraction materials inseparation and enrichment of metal ions. It also introduced a series of new carbonaceousmaterials (carbon nanotubes, fullerenes and graphene) as well as the ideas and researchsignificance of this paper. The second part of this paper concerned the successful preparation of graphene viareduction of graphite oxide and its characteration using a variety of analytical tools.The third part of this article concerned the develoption of a new method using grapheneas column packing of solid phase extraction coupled with flame atomic absorptionspectrometry for the determination of trace cadmium(Cd2+) in water samples. Someeffective parameters on enrichment were selected and optimized. Under optimumconditions, an enrichment factor of125was obtained. The calibration graph was linear inthe range of10.0-120.0μg L-1with a detection limit of0.54μg L-1. The relative standarddeviation (RSD) for ten replicate measurements of10.0μg L-1and80.0μg L-1Cd2+were3.57%and2.63%, respectively. The method has been applied to the analysis of Cd in tap,river, and sea water samples with satisfactory results. Compared with other adsorbentsreported in the literatures, graphene has a good adsorption properties and selectivity.The forth part of this article concerned the develoption of a new method using grapheneas column packing of solid phase extraction coupled with flame atomic absorptionspectrometry for the determination of trace copper (Cu2+) in water samples. Some effectiveparameters on enrichment were selected and optimized. Under optimum conditions, anenrichment factor of150was obtained. The calibration graph was linear in the range of10.0-180.0μg L-1with a detection limit of0.27μg L-1. The relative standard deviation(RSD) for ten replicate measurements of10.0μg L-1and70.0μg L-1Cu2+were3.68%and3.35%, respectively. The method has been applied to the analysis of Cu in tap, river, andsea water samples with satisfactory results. Compared with other adsorbents reported in theliteratures, graphene has a good adsorption properties and selectivity.The fifth part of this article concerned the develoption of a new method using grapheneas column packing of solid phase extraction coupled with flame atomic absorptionspectrometry for the determination of trace lead (Pb2+) in environmental samples. Someeffective parameters on enrichment were selected and optimized. Under optimumconditions, an enrichment factor of125was obtained. The calibration graph was linear inthe range of10.0-600.0μg L-1with a detection limit of0.61μg L-1. The relative standarddeviation (RSD) for ten replicate measurements of10.0μg L-1and400.0μg L-1Pb2+were3.56%and3.25%, respectively. The method has been applied to the analysis of Pb in waterand vegetable samples with satisfactory results. Compared with other adsorbents reportedin the literatures, graphene has a good adsorption properties and selectivity.The sixth part of this article concerned the develoption of a new method using grapheneas column packing of solid phase extraction coupled with flame atomic absorptionspectrometry for the determination of trace cobalt (Co2+) and nickel (Ni2+) inenvironmental samples. Some effective parameters on enrichment were selected andoptimized. Under optimum conditions, an enrichment factor of200was obtained. Thecalibration graph was linear in the range of4.0-200.0and5.0-200.0μg L-1with the detection limits of0.36and0.51μg L-1, respectively. The relative standard deviation (RSD)for ten replicate measurements of100.0μg L-1Co2+and100.0μg L-1Ni2+were3.20%and3.60%, respectively. The method has been applied to the analysis of Co and Ni in waterand vegetable samples with satisfactory results. Compared with other adsorbents reportedin the literatures, graphene has a good adsorption properties and selectivity.