为提高激光诱导击穿光谱(laser induced breakdown spectroscopy,LIBS)技术定量分析的精度,开展了磁场约束下LIBS技术对土壤中重金属元素检测的研究,并采用多谱线强度归一化内标法进行数据处理。通过比较磁场强度分别为0 T、0.3 T、0.8 T、1.25 T时的光谱特性,得到光谱强度和信噪比(signal-to-noise ratio,SNR) 随磁场强度增大而增大,在1.25 T磁场强度时,样品 元素Cd和Cu的光谱强度和SNR要比无磁场作用分别增强了34.77%、56.33%和40.83%、74.12%,构建了磁场强度为1.25 T时的Cd和Cu元素定量分析模型。结果显示,相对于传统内标法,采用多谱线强度归一化内标法的元素检测限分别从52.78 mg/kg和49.18 mg/kg降低到23.87 mg/kg和18.06 mg/kg；相关系数分别从0.961 3和0.942 7提高到0.996 9和0.999 3。本实验研究改善了LIBS的光谱特性,提高了定量分析的精度,采用多谱线强度归一化内标法降低了重金属的检出限和测量误差。

In order to improve the accuracy of quantitative analysis of laser induced breakdown spectroscopy (LIBS) technology, the research on the detection of heavy metal elements in soil by LIBS technology under the confinement of magnetic field was carried out,and the data were processed by multi spectral line intensity normalized internal standard method.By comparing the spectral characteristics when the magnetic field intensity was 0 T,0.3 T,0.8 T and 1.25,respectively,it was obtained that the spectral intensity and signal-to-noise ratio (SNR) increased with the increase of magnetic field intensity. When the magnetic field intensity was 1.25 T,the spectral intensity and SNR of Cd and Cu were 34.77%,56.33%,40.83% and 74.12% higher than that without magnetic field,respectively.The quantitative analysis model of Cd and Cu was constructed when the magnetic field intensity was 1.25 T.The results showed that compared with the traditional internal standard method,the element detection limits of the multi spectral intensity normalized internal standard method were reduced from 52.78 mg/kg and 49.18 mg/kg to 23.87 mg/kg and 18.06 mg/kg,respectively.The correlation coefficients increased from 0.961 3 and 0.942 7 to 0.996 9 and 0.999 3,respectively.In this experiment, the spectral characteristics of LIBS are improved,the accuracy of quantitative analysis is improved,and the detection limit and measurement error of heavy metals are reduced by using the multi spectral line intensity normalization internal standard method.

国家自然科学基金(62173122)、河北省自然科学重点项目(F2021201031)和河北省引进留学人员资助项目 (C20210312)资助项目