Research On Laser-induced Breakdown Spectroscopy System And Detection Of Metal Elements In Water

As the basis of the operation of nature and the development of human society,the quality of water resources determines the quality of life.Healthy water resources and water environment are the barrier of the state of natural environment and the safety of human life.Faced with the increasingly serious water pollution,water quality detection plays an important role in water resources assessment and water environment protection.Laser-induced breakdown spectroscopy is a new method for elemental analysis based on atomic emission spectroscopy.Compared with other traditional detection methods,LIBS has many advantages such as short-time and multi-element analysis,as well as no morphological restriction and additional contamination to samples.In this paper,the application of this technology in qualitative analysis and quantitative detection of metal elements in water is studied.Firstly,based on the basic principle of laser-induced breakdown spectroscopy,the hardware and software system of laser-induced breakdown spectroscopy is designed and built.The hardware part of the system is composed of pulse laser,lens,optical fiber,spectrometer,photoelectric conversion and delay module.The software program is developed based on LabVIEW platform,including real-time control of the system,reading of spectral information,processing of spectral data,qualitative analysis and quantitative calculation.Secondly,several typical solid metal samples such as solder and phosphor bronze were selected to verify the spectral pretreatment,qualitative and quantitative analysis functions of the system.The test results show that the software and hardware of the system work normally and can be used for the subsequent detection of actual water samples.Finally,the system is used to carry out laboratory calibration and actual water samples related experiments and analysis.With graphite flake as the enrichment substrate of liquid sample,the external standard experiments of Cu,Ca,Mn,Al,Cr and the internal standard experiment with Na as internal standard element were carried out,and the calibration models were established respectively.The experimental results of each element showed good linear relationship.On this basis,different actual water samples were collected.In addition to the common elements Na,Mg,Ca,Sr and Ba,the samples from tap water,river estuary water and three places of seawater may also contain metal pollution such as Cr,Fe,Mn,Al and Cu.Based on the established calibration models,some elements of each sample were quantitatively calculated,and the predicted values of their contents were obtained.Among them,the kinds of metal pollution elements detected in the water samples of Yuanyao sea area were the least and the content was relatively low.The results show that laser-induced breakdown spectroscopy can be used as a semi quantitative or quantitative auxiliary method in the actual detection of metal elements in water samples.