Plasma characteristics and quantitative analysis of Pb and Ni in soil based on LIBS technology

When measured by laser induced breakdown spectroscopy, the characteristic parameters of the plasma fluctuate significantly with the experimental parameters, which would have a greater impact on the quantitative measurement. The effects of two experimental parameters, lens to sample distance (LTSD) and delay time, on plasma temperature and electron density were analyzed. Thereafter the optimal LTSD and delay time for quantitative analysis of Pb and Ni in soil were identified. Two element calibration curves were calculated by the internal standard method under the optimal LTSD and delay time. About the two elements, correlation coefficient of the calibration curves is above 0.993. The maximum relative standard deviation (RSD) were 4.47% and 4.76%, respectively, and the maximum relative errors were 12% and 4.8%, respectively. The experimental results showed that laser induced breakdown spectroscopy method in combination with plasma characteristic parameter analysis shows the advantage on quantitative analysis of heavy metals in soil.