Application of High Pressure Pelletised Sample and LIBS in the Determination of Rare Earth Elements in Soil Samples
XU Jin-li1, 2, HU Meng-ying1, 2, ZHANG Peng-peng1, 2, XING Xia1, 2, BAI Jin-feng1, 2, ZHANG Qin1, 2*
1. Institute of Geophysical and Geochemical Exploration，Chinese Academy of Geological Sciences, Langfang 065000，China
2. UNESCO International Centre on Global-Scale Geochemistry, Langfang 065000，China
Abstract：The traditional laser induced breakdown spectroscopy (LIBS) was mostly used in the qualitative analysis of materials, because the instruments have such shortcomings as low repeatability and poor accuracy in quantitative analysis, which fails to meet the requirements of quantitative analysis on accuracy and precision. In recent years, both in hardware and software, LIBS technology has developed rapidly. Based on the outstanding advantages of LIBS technology, such as simple and fast, this method achieves multi-element quantitative analysis by one injection at the same time, and the satisfactory results have been obtained. In order to apply LIBS technology to the quantitative analysis of rare earth elements in soil samples, this paper optimizes the working conditions of LIBS technology and determines the best working conditions: Output (1.6 mJ), Gate Delay (0.1 μs), Spot Diameter (100 μm), Laser Repetition Rate (20 Hz), He (0.3 L·min-1). The analysis samples use the ultra-high pressure sample preparation technology, which improves the plasticizing effect of the sample, makes the surface more compact and flat, and effectively reduces the powder effect of the sample. With the increase of the sample preparation pressure, the characteristic spectrum of the sample shows that the baseline is obviously less, the noise is reduced, and the signal to back ratio and the precision of the measurement results are improved. The laser ablation of fresh surface greatly reduces the influence of thermal effect and improves the accuracy of the measurement results. The soil standard material (matrix matching) is used as a calibration curve, which decreases the influence of matrix effect and increases the accuracy of determination results. The method has been verified by the soil certified reference materials, and the measured value is consistent with the certified value. Although the relative error of the LREE analysis results is large, this method realizes the simultaneous determination of multiple elements using LIBS technology, promotes the application and development of LIBS technology in the field of exploration geochemistry and also provides a new idea for the popularization and application of LIBS technology in other fields.
徐进力，胡梦颖，张鹏鹏，邢 夏，白金峰，张 勤. 高压制样-LIBS技术测定土壤样品中稀土元素的应用研究[J]. 光谱学与光谱分析, 2020, 40(12): 3806-3811.
XU Jin-li, HU Meng-ying, ZHANG Peng-peng, XING Xia, BAI Jin-feng, ZHANG Qin. Application of High Pressure Pelletised Sample and LIBS in the Determination of Rare Earth Elements in Soil Samples. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2020, 40(12): 3806-3811.
