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.

中文翻译：

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基于最大似然估计的激光诱导击穿光谱法检测和分析土壤中的Cd

镉是一种剧毒元素，对人体健康有很大影响。但土壤中镉的检测仍然是一个挑战。本研究旨在提高激光诱导击穿光谱 (LIBS) 测量土壤中痕量元素镉的分析能力。制备了十二个含有梯度 Cd 元素的土壤样品。使用常规的单变量校准模型和最大似然估计算法对样品浓度进行定量分析和比较。校准分析表明，通过传统的单变量校准和最大似然（ML）估计，拟合的 R2 值分别为 0.965 和 0.990。ML估计具有更高的稳定性，预测的浓度更准确。最后，估计 Cd 的检出限为 7。