State Key Laboratory of Urban and Regional Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, China.
Environ Sci Process Impacts. 2013 Sep;15(9):1768-74. doi: 10.1039/c3em00250k.
The technique of diffusive gradients in thin films (DGT) is often employed to quantify labile metals in situ; however, it is a challenge to perform the measurements in-field. This study evaluated the capability of field-portable X-ray fluorescence (FP-XRF) to swiftly generate elemental speciation information with DGT. Biologically available metal ions in environmental samples passively preconcentrate in the thin films of DGT devices, providing an ideal and uniform matrix for XRF nondestructive detection. Strong correlation coefficients (r > 0.992 for Mn, Cu, Zn, Pb and As) were obtained for all elements during calibration. The limits of quantitation (LOQ) for the investigated elements of FP-XRF on DGT devices are 2.74 for Mn, 4.89 for Cu, 2.89 for Zn, 2.55 for Pb, and 0.48 for As (unit: μg cm(-2)). When Pb and As co-existed in the solution trials, As did not interfere with Pb detection when using Chelex-DGT. However, there was a significant enhancement of the Pb reading attributed to As when ferrihydrite binding gels were tested, consistent with Fe-oxyhydroxide surfaces absorbing large quantities of As. This study demonstrates the value of the FP-XRF technique to rapidly and nondestructively detect the metals accumulated in DGT devices, providing a new and simple diagnostic tool for on-site environmental monitoring of labile metals/metalloids.
扩散梯度薄膜（DGT）技术常用于原位定量分析生物可利用金属；然而，在野外进行测量具有挑战性。本研究评估了现场便携式 X 射线荧光（FP-XRF）在 DGT 上快速生成元素形态信息的能力。环境样品中的生物有效金属离子通过 DGT 装置的薄膜被动预浓缩，为 XRF 非破坏性检测提供了理想且均匀的基质。在标定过程中，所有元素均获得了强相关系数（r>0.992 用于 Mn、Cu、Zn、Pb 和 As）。FP-XRF 在 DGT 装置上对所研究元素的定量限（LOQ）分别为 2.74μg cm(-2)的 Mn、4.89μg cm(-2)的 Cu、2.89μg cm(-2)的 Zn、2.55μg cm(-2)的 Pb 和 0.48μg cm(-2)的 As。在溶液试验中当 Pb 和 As 共存时，当使用 Chelex-DGT 时，As 不会干扰 Pb 的检测。然而，当测试铁氢氧化物结合凝胶时，Pb 的读数显著增强，这与 Fe-oxyhydroxide 表面吸附大量 As 一致。本研究表明，FP-XRF 技术具有快速、非破坏性检测 DGT 装置中积累金属的价值，为现场环境监测生物有效金属/类金属提供了一种新的简单诊断工具。
