Detection and analysis of Cd in soil by laser-induced breakdown spectroscopy based on maximum likelihood estimation

Cd is an extremely toxic element and has a great impact on human health. But the detection of Cd in the soil is still a challenge. This study aimed to improve the analytical ability of laser-induced breakdown spectroscopy (LIBS) to measure Cadmium, the trace elements in the soil. Twelve soil samples containing gradient Cd elements were prepared. The sample concentration was quantitatively analyzed and compared by using the conventional univariate calibration model and maximum likelihood estimation algorithm. Calibration analysis revealed that the fitted R2 values are 0.965 and 0.990 by the conventional univariate calibration and maximum likelihood (ML) estimation respectively. The ML estimation has higher stability and predicted concentration is more accurate. Finally, the detection limit of Cd was estimated to be 7.84 μg/g by using the proposed algorithm to correct the intensity.