Detection Of Trace Elements In Water With Inorganic Nanomaterials Concentrated By X-ray Fluorescence Spectrometry

The pollution of metal ions in water sample has attracted widespread attention in public health and environmental safety.In environmental water samples,the content of many metal ions is extremely low.Therefore,the rapid detection of trace heavy metal elements in environmental water samples is of great significance for water quality monitoring.Compared with other on-site inspection technologies,X-ray fluorescence spectrometry(XRF)has been widely used in the field of solid sample detection due to its high degree of automation and the ability to achieve simultaneous detection of multiple elements.However,it is difficult to analyze directly for trace metal ions in water sample for the hand-held XRF,due to insufficient limits of detection and matrix effects.This work aims to improve the analytical performance of handheld XRF and meet the on-site rapid requirements for trace metal ions in environmental water samples.Based on inorganic nanomaterials as adsorbents of the dispersive microsolid phase extraction(DMSPE)procedure,in combination with hand-held XRF technology to establish an analytical method that can detect trace metal ions in water,and the analytical performance of the method was examined.The details are as follows:1.Preparation of flower-like magnesium silicate(FMS)by a one-step mixed solvothermal process.FMS as adsorbent of the DMSPE procedure in combination with hand-held XRF established an analytical method(FMS-DMSPE-XRF).The morphology and structure of FMS was characterize,preconcentration conditions were optimized,and coexisting ions interference were investigated.The performance of the method was studied and the actual water sample was analyzed.The accuracy of the analysis method was verified.The rapid selective detection of Pb2+,Zn2+ and Cu2+ was achieved.The limits of detection were 0.57,0.69 and 0.76 ng·mL-1,respectively.It is superior to the detection limits of other enriched materials such as tubular and lamellar materials with hand-held XRF.RSD was less than 5%.The comparison of the actual water sample results with ICP-MS,relative errors was less than 4%,except Cu2+(7.6%).The synthesis method of FMS is simple and environmentally friendly.As metal ions of preconcentrated material in actual water sample,it has a good application prospect.2.The GO/MWCNTs composite nanomaterials with layered stack structure was prepared by ultrasonicating GO and oxidized MWCNTs.GO/MWCNTs as adsorbent of the DMSPE procedure in combination with hand-held XRF established an analytical method(GO/MWCNTs-DMSPE-XRF).The morphological and structural characterization of GO/MWCNTs was investigated.The isotherm adsorption process of GO/MWCNTs for metal ions and the adsorption capacity of metal ions were studied.The preconcentration conditions were optimized.The performance of the method is studied and the actual water samples are analyzed.The accuracy of the analysis method was verified.Simultaneous preconcentration and XRF detection of eight kinds of metal elements such as Ni2+,Cu2+,Zn2+,Co2+,Fe3+,Mn2+,Cr3+ and Pb2+ were realized.The limits of detection were 0.44,0.96,0.95,1.14,0.84,1.41,0.94 and 1.73 ng mL-1,respectively.The actual water sample test results compared with ICP-MS results,relative errors are less than 5%.This method not only reduces the detection limit of hand-held XRF,but also increases analyzable metal elements and extends the range of applications.