Analysis And Application Of Liquid Sample Matrix Transformation Based On Laser Induced Breakdown Spectroscopy

Laser-Induced Breakdown Spectroscopy(LIBS)technology,as a rising star in elemental analysis,has been successfully used in the analysis and detection of metal elements in the water environment due to its unique analytical advantages.But,owing to plasma quenching,solution sputtering,surface ripples,matting and short plasma lifetime,the performance of LIBS technology in water sample analysis is not satisfactory.Therefore,the use of LIBS technology to directly analyze the elements in the water environment is still a considerable challenge.Liquid-solid matrix conversion technology is currently a more popular method for LIBS to detect liquids.While overcoming the above-mentioned problems,it can also achieve LIBS signal enhancement and improve the sensitivity of LIBS to detect water sample elements.In this method,the choice of matrix material is the key to success.In view of this,this paper chose different types of solid-phase support matrix,established a liquid sample matrix conversion analysis method based on different materials,and combined with LIBS technology for the detection of metal elements in water samples.At the same time,the analytical performance of the established analytical method applied to the detection of heavy metal elements in actual samples was evaluated.The main research contents and innovations are as follows:(1)In the first study,we chose D190 thiol chelating resin as the solid phase matrix and applied it to the analysis of heavy metals in LIBS water samples for the first time.In order to obtain a better extraction effect,the univariate method was used to study the effects of solution p H,resin dosage,contact time and delay time on the extraction effect and LIBS performance.The proposed method was used to accurately determine the Ag and Cr in the actual water samples,the recovery rate was 88.3%～107.9%,and the RSD was less than 10.6%.The results show that the new technology has broad application prospects in water sample analysis.(2)Based on the starting point of combining liquid-solid matrix conversion and LIBS technology for water sample analysis,in this study,the green material Chitosan(Chitosan,CS)was selected as the solid-phase matrix,and solvent-assisted dispersion solid-phase extraction was introduced for the first time.(Solvent-assisted dispersive solid phase extraction,SADSPE)technology,so that the traditional liquid-solid matrix conversion technology can be sublimated.This technology significantly improves the adsorption efficiency of the adsorbent and overcomes the disadvantages of heterogeneous adsorption.It has a good adsorption effect on Ag,Cr,Pb,Cu,Co and Ni,and further reduces the LOD.At the same time,we also used SEM,TGA,XPS and other technologies to study the extraction mechanism and plasma characteristics.In the actual sample analysis,the recovery rate is 85.11%～109.45%,and the RSD is less than10.94%,which meets the technical requirements of LIBS.The analytical method established in this study further solves the problems existing in the analysis of heavy metal elements in the detection of liquid samples by LIBS technology,and has important application prospects.(3)On the basis of the second work,this study uses CS as a raw material,introduces poly(vinyl alcohol)(PVA)and polyethyleneimine(PEI),combined with a new method to synthesize adsorption Porous composite membrane material with better effect.Compared with a single CS homogeneous solution,the porous composite membrane can hold more target samples,and because of its rough surface,the coupling efficiency to the laser is higher.At the same time,the stability of the membrane and the content of functional groups have increased.As a new type of liquid-solid conversion matrix material,the membrane can successfully detect Ag,Cr,Pb and Cu in combination with LIBS technology.This method further improves the sensitivity of the LIBS method.It is expected to combine it with the membrane stent to replace the inactive filter membrane,opening up a new way for the rapid analysis of solution samples by LIBS technology.