激光诱导击穿光谱结合多元非线性方法定量分析土壤中锰

锰元素是植物所需的微量元素之一。采用激光诱导击穿光谱(laser-induced breakdown spectroscopy,LIBS)技术对土壤中锰元素进行定量分析。以46个土壤样品为研究对象,获取土壤激光诱导击穿光谱数据,选取锰元素403.1nm的特征谱线为分析线。根据谱线强度与元素浓度建立定标曲线,相关系数仅为0.78,定标结果说明,由于土壤样品成分的复杂性,锰元素浓度受土壤基体效应影响严重,应根据锰元素在土壤中的存在形式,选取相关元素,建立多元非线性回归定量分析方法,消除基体效应,从而提高LIBS测量的准确性。在多元非线性回归方法中分别考虑碳和铁元素对锰元素浓度的影响。与定标曲线相比,在考虑碳和铁元素对锰元素影响时,LIBS预测浓度与参考浓度的相关系数为0.97,相对误差为3.2%~10.3%,测量的准确度得到提高。实验结果表明,将多元非线性回归方法和激光诱导击穿光谱技术结合可以对土壤中微量锰元素进行定量分析。

Quantitative Analysis of Mn in Soil Based on LIBS with Multivariate Nonlinear Method

Manganese (Mn) is one of the indispensable micronutrients for plants .The concentration of Mn in soil was deter‐mined with laser‐induced breakdown spectroscopy (LIBS) in this paper .Forty‐six soil samples were used to obtain the spectrum data of LIBS .The characteristic line of 403.1 nm was selected as the analytical line of Mn .The calibration curve of the net in‐tensity of Mn line at 403.1 nm versus the corresponding concentration was constructed withthe correlation coefficient 0.78 .The results showed that ,due to the complex chemical compositions of soil samples ,the calibration method influenced by the matrix effect seriously .It should utilize more information of LIBS spectra to construct the multivariate nonlinear calibration method , which can reduce the matrix effect and improve the measurement accuracy of LIBS .With multivariate nonlinear calibration meth‐od ,the interference effect of C and Fe elements on the concentration of Mn was considered .Compared with calibration method , the correlation coefficient of the prediction concentration of LIBS with reference concentration was 0.97 ,and the relative meas‐ured error was in the range 3.2% ~10.3% ,Therefore ,the measurement accuracy of LIBS was increased .The experimental re‐sults demonstrate that LIBS combined with multivariate nonlinear calibration method can be used to quantitative analysis of Mn in soil .