Applications Of Flow Injection-solid Phase Extraction System In Metal Ions Detection

With the development of industrialization, many accumulative and toxic metalions enter environment inevitably, which causes serious environmental pollutionproblems and threatens people’s health. It is important and challenging work todesign a novel, simple and rapid method with good sensitivity and accuracy todetermine the metal ions in different samples. However, it is difficult to determinesuch metal ions by most analytical techniques because of the low concentrations andmatrix interferences. So a preconcentration and separation step is necessary prior todetermining.Solid phase extraction is a widely used method for preconcentration andseparation of trace metal ions because of its special advantages such as less organicsolvent consumption, good selectivity, no phase separation and easy to combine withflow injection analysis. Many materials including active carbon, silica gel and nanomaterials have been used as sorbents for pretreating metal ions. Developing new andeffective adsorbing materials has become a hot spot. In this work, two newadsorption materials are synthesized in order to preconcentrate and separate tracemetal ions and a series of experiments is launched around their adsorptive property.（1） Sol-gel method is employed to synthesize TiO₂/graphene composite（TiO₂/GN） as a novel adsorption material. The material is enclosed in a microcolumnto build a flow injection-solid phase extraction system （FI-SPE） to preconcentratetrace La, Tb, and Ho prior to their determinations by microwave plasmatorch-atomic emission spectrometry （MPT-AES）. The experimental parametersincluding sample flow rate, sample loading time, sample pH, eluent concentrationand eluent flow rate are investigated in detail and the optimal conditions areestablished. Under the optimum experimental conditions, the detection limits of La, Tb, and Ho are2.2,1.6, and2.8μg/L respectively. The proposed method has beensuccessfully applied to detect La, Tb, and Ho in rare earth oxide samples.（2） Poly （aryl ether ketone） containing pendant carboxyl groups （PEK-L） ispacked in the microcolumn to build a FI-SPE-MPT-AES system for thepreconcentration and determination of arsenic （As） and antimony （Sb）. Under theoptimal experimental conditions, the detection limits of As and Sb are0.27and0.38μg/L respectively.