X射线荧光光谱法测定土壤样品中的氟

Determination of Fluorine in Soil Sample by X-Ray Fluorescence Spectrometry

污染的土壤及水系沉积物中氟(F)具有长期积累效应,因此测定土壤中的F具有重要意义。F是超轻元素,激发效率低,荧光产额低,且在光路中易被吸收。为提高F测定的分辨率,改善信背比,本研究使用PX8晶体为分析晶体,比PX1晶体信背比提高近2倍。低原子序数元素X射线的强度在很大程度上取决于基体的组分,为减少吸收/增强效应对F测定的影响,仅采用35个土壤标准物质建立F的校准曲线,经谱线重叠干扰校正、基体效应校正,方法的线性关系良好(R 2=0.978),测定限为50μg/g。采用28个土壤样品验证方法的可靠性,结果表明,X射线荧光光谱法可满足土壤样品中F测定误差的要求。

Non-metallic fluorine as a pollutant has an important impact on human health and ecosystem. Fluorine in contaminated soil and sediment has long-term accumulation effect. Therefore, the determination of fluorine in soil is of great significance. Fluorine is an extra-light element, the excitation efficiency is low, the fluorescence yield is low, and it is easy to be absorbed in the optical path. In this study, to improve the resolution of fluorine determination, PX8 crystal was applied and the ratio of peak to background of PX8 crystal was nearly 2 times higher than that of PX1 crystal. The X-ray intensity of low atomic number element depended on the composition of matrix to a great extent. To reduce the influence of absorption/enhancement effect on fluorine determination, the calibration curve of fluorine was established by 35 soil reference materials only. The line overlap and matrix interference were corrected by empirical coefficients, and the linearity was good ( R 2=0.978). The limit of determination of a method (LDM) was 50 μg/g. The method was successfully used for detection of fluorine in 28 soil samples. The results showed that the values of fluorine in soil determined by X-fluorescence could meet the error requirement of the analysis.