Determination of Cd Content in Soil Using Laser-Induced Breakdown Spectroscopy Couple with Chemometric Methods

Heavy metal pollution in soil affects agriculture and food safety，and rapid detection of heavy metal pollution is an urgent problem to be solved.Laser induced breakdown spectroscopy（LIBS）couple with chemometrics methods were employed to conduct quantitative analysis of Cd content in soil.First，soil samples with 15 concentration gradients of Cd were manually made up.Then，the LIBS emission lines of all soil samples were collected.Preprocessing methods were used to eliminate errors and noise of spectral data.Then，characteristic lines and spectral regions of Cd were determined based on LIBS spectra.Quantity regression models based on partial least squares regression（PLSR）and back propagation-artificial neural network（BP-ANN）were set up and results were compared.As a result，models based on non-linear methods（BP-ANN）offered a promising results than linear methods of PLSR.Probable reason was that non-linear methods had an advantage to deal with matrix effects of soil automatically.Results indicated that LIBS coupled with multiple chemometrics methods could finished the detection of heavy metal Cd，which provided a brand-new analysis approach for heavy metals accurate detection in soil，and could offer theoretical foundation for development of heavy metal testing equipment.