Study on Separation、 Preconcentration and Analysis of Trace Elements with Carbon Nanometer Materials
|School||Wuhan Polytechnic University|
|Keywords||carbon nanometer materials solid phase extraction separation /preconcentration inductively coupled plasma mass spectrometry trace elements|
Due to the rapid development of science and technology,more metals have been used in different industrial and agricultural fields and inevitably discharged into the environment.To evaluate the effects of metals,particularly heavy metals,on the environment,ecosystem and the health of human beings,sensitive,fast,reproducible,simple and accurate analytical methods are often required for the determination of trace elements in environment samples.Although the detection power of instruments has been greatly improved , the direct determination of trace elements at extremely low concentration levels is often very difficult owing to the insufficient sensitivity of the method , the matrix interferences and contamination in the reagents and/or lab environment.Therefore,matrix separation and preconcentration procedures are often required prior to the measurement step.Among many separation and preconcentration methods,the solid phase extraction has become a interesting separation and preconcentration method because of the following advantages:high preconcentration factor,high recovery,rapid phase separation,a small amount of organic solvent consumption,the ability to be used with different detection techniques and convenient operation.In solid phase extraction,adsorbent has an important influence on analytical performances.Therefore,the choice of adsorbent is the key to extract target substances . In recent years, nanometer-size materials have drawn growing attention in analytical sciences because of their special properties.One of these properties is that most of the atoms of nanoparticle reside on the surface.The surface atoms are unsaturated,possess high chemical activity,and can easily bind with other atoms.Consequently,interest in adapting nanometer material as a new adsorbent for the preconcentration and separation of substance has increased significantly.Inductively coupled plasma mass spectrometry (ICP-MS) is a very good trace/ultra-trace element analysis technique.It has the following advanges:low detection limit,high sensitivity,wide linear dynamic range,rapid multi-element detection capability with high sensitivity . ICP-MS has been applied to the determination of trace/ultra-trace elements in geology,environment,materials and biology samples.The purpose of this study is to develop new methods using a microcolumn packed with carbon nanometer materials (such as single-walled carbon nanotubes , multi-walled carbon nanotubes and carbon nanofibers) coupled to inductively coupled plasma mass spectrometry(ICP-MS) for the preconcentration and determination of trace/ultra-trace elements in biological and environmental samples.The aim of this dissertation are described as follows:(1) The potential of multi-walled carbon nanotubes (MWNTs) as a solid-phase extraction adsorbent for the separation and preconcentration of trace precious metal (Pd)was investigated by inductively coupled plasma mass spectrometry(ICP-MS).The chief parameters such as pH,sample flow rate,sample volume,concentration of eluent and interference of coexisting ions were optimized . A new method for separation/preconcentration of trace precious metal element was described and applied to the analysis of geology sample.(2) A simple and convenient method has been developed for the determination of heavy metal element(Cd)by adsorption on the single-walled carbon nanotubes coupled with ICP-MS.The proposed method has been successful applied to the analysis of the biology sample.(3) Based on carbon nanofibers as a novel solid phase extraction adsorbent,the adsorption behavior of metal elements (Cu,Zn,Pb) was studied by ICP-MS in dynamic conditions.The optimum adsorption and desorption conditions were explored,The developed method was successfully applie to the analysis of the real sample.