Sample Pretreatment Combined With Inductively Coupled Plasma Mass Spectrometry To Analyze Trace Metal Elements In Environmental

The rapid development of battery manufacturing,petroleum refining,mining,smelting,printing,leather and other industries need to consume a lot of metal elements,but also produce a large number of waste water,waste gas and waste residue containing harmful metal elements,if not handled properly,some harmful metal elements may enter the environment.The content and form of metal elements have a far-reaching impact on living organisms and ecological environment,so it is of great significance to monitor trace metal elements in food,environment,biology and other samples.It is necessary to establish a rapid,accurate and efficient method for the analysis and detection of metal elements.At present,a variety of analysis and detection methods have been developed.Among them,ICP-MS technology,which was born in the mid-1980s,is recognized as the most powerful tool for quantitative analysis of inorganic metal elements because of its low detection limit（ppt level）,wide linear range and rapid simultaneous analysis of multi-elements.However,in addition to trace or ultra-trace metal elements,most of the actual samples,such as environmental water samples,food samples and biological samples,have complex matrix and more interference components,which may cause potential matrix effects,mass spectrometry interference,ion interference and so on.Direct sample injection will adversely affect the accuracy of ICP-MS detection results.In order to eliminate the matrix effect and mass spectrometry interference as much as possible,several different sample pretreatment methods were used to separate and enrich the target elements in complex matrix samples.The main contents are as follows:（1）Novel carboxyl functionalized tetrazole adsorbents were synthesized,and a new method for separation and enrichment of trace rare earth elements in seawater samples by synchronous magnesium hydroxide coprecipitation-dispersed solid phase extraction was developed.The effects of sample solution p H,matrix type and concentration,eluent type and concentration,extraction time were investigated.The adsorption mechanism of dispersed solid phase extraction and magnesium hydroxide coprecipitation and the potential synergistic effect between them were discussed.The optimum extraction conditions of synchronous magnesium hydroxide coprecipitation-dispersed solid phase extraction were as follows:p H of sample solution 9.0,dosage of adsorbent 5mg,concentration of precipitant Mg²⁺is 0.05mol L^-1,rare earth ions could be quantitatively adsorbed after vortex mixing for 5 minutes,and the eluent was HNO₃with 0.3 m L concentration of 0.5mol L^-1.For the simulated seawater solution,the concentration of rare earth ions is in the linear range of 1～100 ng L^-1,and the linear coefficient is good（R²:0.9912～0.9997）.For 15 kinds of rare earth elements,the LOD is between 0.003 ng L^-1（Lu）and 0.201ng L^-1（Eu）,the enrichment factor is between63.8 and 71.3,and the RSD is between 0.26 and 4.17%.The method has been applied to the determination of rare earth elements in Canadian standard seawater sample CASS-6.The relative standard deviation between the detection results and the reference value is in the range of 1.1 to 4.6%,and the recovery is between 95.6%（Eu）and 103.5%（Tm）.It is proved that this method can be effectively used for the separation and enrichment of rare earth ions in complex matrix samples such as seawater.Simultaneous magnesium hydroxide coprecipitation-dispersed solid phase extraction（ICP-MS）is a rapid and efficient method for the determination of trace or ultra-trace rare earth elements in environmental samples.（2）A new sulfhydryl functionalized adsorbent material was synthesized,and a method for speciation analysis of chromium in environmental samples by on-line reduction-solid phase extraction（（SPE））coupled with ICP-MS was established.The effects of sample solution p H,sample volume flow rate（Q）,elution conditions and reduction conditions were investigated.The optimum conditions were determined as follows:sample solution p H 4.0,sample volume flow 0.4 m L min^-1,eluent volume flow 0.2 m L min^-1,eluent HNO₃;reductant with 0.2 m L concentration 0.6 mol L^-1 and hydroxylamine hydrochloride with 20 m L concentration 80 mmol L^-1.The analytical performance of the method was evaluated.The linear coefficient was good in the linear range of 0.05～5.0μg L^-1（the detection limit of R²:0.9994）,Cr（III）was 0.012μg L^-1,and the inter-day and intra-day RSD were 3.1%and 2.3%,respectively.The method has been applied to the speciation analysis of chromium in environmental samples.the recoveries of,Cr（III）and Cr（VI）are more than 90%,and the quantitative recovery of Cr（III）and Cr（VI）can be realized.It is proved that the method is suitable for the speciation analysis of chromium in environmental samples.