Multi-element analysis of heavy metal content in soils using laser-induced breakdown spectroscopy: A case study in eastern China

Laser induced breakdown spectroscopy is an emerging elemental analytical technique with the advantage of fast response, minimal sample preparation and multi-element analysis capacities. This work studied practical use of LIBS for rapid quantification of 4 (Cu, Ni, Cr, Pb) heavy metal elements in 169 agricultural soil samples. The objective is to conclude an appropriate method to reduce the interference of matrix effect in soils within the scope of data analysis, by comparing several univariate and multivariate methods of LIBS data interpretation (full spectrum and emission lines). The proposed multivariate methods, such as the least absolute shrinkage and selection operator and principal components regression were found to be effective in reducing the matrix interference and the predictive performance was stable in our experiment, approaching normalized root mean squared error of 6.84%, 8.87%, 9,71%, 10.76% for Cu, Ni, Cr and Pb, respectively. Meanwhile, the performance of univariate analysis suffered from such effect. The results showed the importance of utilizing proper multivariate chemometrics for LIBS data interpretation when quantifying the heavy metals in soils.