Institute for Plant Production and Agroecology in the Tropics and Subtropics, Universität Hohenheim, Garbenstr. 13, 70599 Stuttgart, Germany; World Agroforestry Centre (ICRAF), P.O. Box 30677, Nairobi 00100, Kenya.
Sci Total Environ. 2013 Oct 1;463-464:374-88. doi: 10.1016/j.scitotenv.2013.05.068. Epub 2013 Jul 3.
Total X-ray fluorescence spectroscopy (TXRF) determines concentrations of major and trace elements in multiple media. We developed and tested a method for the use of TXRF for direct quantification of total element concentrations in soils using an S2 PICOFOX™ spectrometer (Bruker AXS Microanalysis GmbH, Germany). We selected 15 contrasting soil samples from across sub-Saharan Africa for element analysis to calibrate the instrument against concentrations determined using the inductively coupled plasma-mass spectroscopy (ICP-MS) standard method. A consistent underestimation of element concentrations using TXRF compared to ICP-MS reference analysis occurred, indicating that spectrometer recalibration was required. Single-element recalibration improved the TXRF spectrometer's sensitivity curve. Subsequent analysis revealed that TXRF determined total element concentrations of Al, K, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Ga accurately (model efficacy/slope close to 1:1 line, and R(2)>0.80) over a wide range of soil samples. Other elements that could be estimated with an acceptable precision (R(2)>0.60) compared with ICP-MS although generally somewhat under- or overestimated were P, Ca, As, Rb, Sr, Y, Pr, Ta and Pb. Even after recalibration, compared to ICP-MS the TXRF spectrometer produced underestimations for elements Na, Mg, Ba, Ce, Hf, La, Nd, W and Sm and overestimations for elements Bi, Tl and Zr. We validated the degree of accuracy of the TXRF analytical method after recalibration using an independent set of 20 soil samples. We also tested the accuracy of the analysis using 2 multi-element standards as well as the method repeatability on replicate samples. The resulting total element concentration repeatability for all elements analyzed were within 10% coefficient of variability after the instrument recalibration except for Cd and Tl. Our findings demonstrate that TXRF could be used as a rapid screening tool for total element concentrations in soils assuming that sufficient calibration measures are followed.
全反射 X 射线荧光光谱法（TXRF）可测定多种介质中的常量和微量元素浓度。我们开发并测试了一种方法，使用 S2 PICOFOX™光谱仪（德国布鲁克 AXS 微分析有限公司）直接定量测定土壤中总元素浓度。我们从撒哈拉以南非洲各地选择了 15 个具有代表性的土壤样本进行元素分析，以校准仪器，使其与电感耦合等离子体质谱（ICP-MS）标准方法测定的浓度相对应。与 ICP-MS 参考分析相比，TXRF 对元素浓度的一致低估表明需要重新校准光谱仪。单个元素的重新校准提高了 TXRF 光谱仪的灵敏度曲线。随后的分析表明，TXRF 能够准确测定 Al、K、Ti、V、Cr、Mn、Fe、Ni、Cu、Zn 和 Ga 等元素的总浓度（模型功效/斜率接近 1:1 线，R(2)>0.80），适用于广泛的土壤样本。其他元素虽然通常被低估或高估，但也可以用可接受的精度（R(2)>0.60）与 ICP-MS 进行估计，这些元素包括 P、Ca、As、Rb、Sr、Y、Pr、Ta 和 Pb。即使经过重新校准，TXRF 光谱仪与 ICP-MS 相比，仍会低估 Na、Mg、Ba、Ce、Hf、La、Nd、W 和 Sm 等元素的浓度，高估 Bi、Tl 和 Zr 等元素的浓度。我们使用 20 个独立的土壤样本对重新校准后的 TXRF 分析方法的准确性进行了验证。我们还使用 2 种多元素标准品以及重复样本的分析方法重复性来测试分析的准确性。除了 Cd 和 Tl 之外，所有分析元素的总浓度重复性在仪器重新校准后的 10%变异性系数内。我们的研究结果表明，在遵循充分的校准措施的前提下，TXRF 可以用作土壤中总元素浓度的快速筛选工具。
