Heavy Metals Detection Of Environmental Pollutants Using Laser Induced Breakdown Spectroscopy

Laser Induced Breakdown Spectroscopy is a promising technique for analyzing elements of samples recently.It has many advantages,such as rapid and in-situ analysis,online analysis and simultaneous multi-element detection.It can be used to analyze solid,liquid and gas samples.Firstly,this paper summarized the theoretical fundamental and development status. Then four kinds of LIBS technique and their applications were introduced.In this thesis,three kinds of experimental schemes were employed to analyze heavy metals of samples.The main contents and conclusions of dissertations are as follows:1.The simple pulse（SP-）LIBS was used to detect Cu element in Cu SO₄ solution.The location of laser induced breakdown,laser energy,delay time between the laser and the spectrometer et al. were optimized by Cu I 324.75 nm and Cu I 327.40 nm as analytical spectrums. The limits of detection（ LOD） of 3.98 ppm and 6.81 ppm were attained at optimized conditions through analyzing seven different kinds of Cu element in Cu SO₄ solutions.At the same condition,Cu,Zn,Mg and Cd elements in mixed solution were simultaneously analyzed.2. The dual pulse（ DP-） LIBS was employed to study Cu element in Cu SO₄ solution.Energies ratio and delay time between two laser pulses were optimized by Cu I324.75 nm for higher spectral intensity which was aimed to calculate LOD of Cu element which was found to be 1.92 ppm.We also studied and compared performance of LIBS with various wavelengths combination of nanosecond laser pulses.3.The experimental setup of LIBS with electrostatic field was built for detecting Cu element in Cu SO₄ solution to enhance detection sensitivity of LIBS.We studied the effect of voltage,plates distance,laser energy and delay time between the laser and the spectrometer on spectral intensity of Cu I 324.75 nm,then at optimized conditions calculated Cu element LOD of 2.74 ppm.4.The femtosecond laser plasma filament LIBS（FIBS）was used to analyze heavy metals（Ca,Fe and Cr）in polar leaves.The Ca and Fe elements concentrations in stem and mesophyll from one leaf were detected and compared by corresponding spectral intensities.Heavy metals in Polar leaves from four locations with different environment in Changchun City were analyzed qualitatively by the same way.The reasons for difference in element concentrations of polar leaves from various locations were explained by environmental pollutions.