基于双曲面弯晶技术的高精度便携式X射线荧光光谱法快速测定土壤中10种重金属元素

Rapid Determination of 10 Heavy Metal Elements in Soil by High-definition Portable X-ray Fluorescence Spectrometry Based on Hyperbolic Curved Crystal Technology

摘要:

土壤重金属污染是制约区域生态改善与农产品安全的关键因素，研究快速测定土壤中重金属元素含量具有重要意义。通过系统考察方法的标准曲线、检出限、精密度和正确度等性能指标，并将实际样品测定结果与电感耦合等离子体质谱法（ICP-MS）进行比对，建立了一种基于双曲面弯晶技术的高精度便携式单波长激发-能量色散X射线荧光光谱法（高精度PXRF），快速测定国家土壤标准物质和湖南永州市农田土壤中砷（As）、铬（Cr）、铜（Cu）、锰（Mn）、镍（Ni）、铅（Pb）、锌（Zn）、镉（Cd）、锑（Sb）、钴（Co）10种重金属元素的含量。实验结果显示，在X射线管电压50 kV、电流0.8 mA、测量时间600 s等最优条件下，方法的线性关系较好，土壤中10种目标元素检出限达0.002~7.1 mg/kg，相对标准偏差为0.30%~5.3%，相对误差平均值为－10%~16%，精密度和正确度良好，且与ICP-MS法无显著差异，可以满足土壤样品中As、Cr、Cu等重金属元素的现场快速测定需求。该方法具有便携性好、前处理简单、检测速度快和环境要求低等显著优点，能为土壤重金属的现场应急和预警监测提供有效、快速、科学的技术支撑。

Abstract:

Soil heavy metal pollution is a key factor constraining regional ecological improvement and agricultural product safety. Therefore，developing rapid methods for determining heavy metal content in soil is of great significance. A high-definition portable mono-excitation energy-dispersive X-ray fluorescence spectrometry （HPXRF） method based on hyperbolic curved crystal technology was optimized and established for the rapid determination of ten heavy metal elements，including arsenic （As），chromium （Cr），copper （Cu），manganese （Mn），nickel （Ni），lead （Pb），zinc （Zn），cadmium （Cd），antimony （Sb），and cobalt （Co），in national soil standard reference materials and farmland soil samples collected from Yongzhou City，Hunan Province. Key analytical performance parameters of the method，such as calibration curve linearity，detection limits，precision，and accuracy，were systematically evaluated. The results obtained from real sample analysis were compared with those measured by inductively coupled plasma mass spectrometry （ICP-MS）. Under the optimized conditions （X-ray tube voltage 50 kV，current 0.8 mA，measurement time 600 s），the method exhibited good linearity. The detection limits for the ten target elements in soil ranged from 0.002 to 7.10 mg/kg，the relative standard deviations ranged from 0.30% to 5.3%，and the average relative errors ranged from －10% to 16%. These results indicate satisfactory precision and accuracy. Furthermore，no significant difference was observed between the results obtained by this method and those by ICP-MS. The proposed method meets the requirements for the on-site rapid determination of heavy metal elements such as As，Cr，and Cu in soil samples. With its significant advantages，including good portability，simple sample pretreatment，fast analysis speed，and low requirements for operating environment，this method can provide an effective，rapid，and scientific technical support for on-site emergency response and early warning monitoring of soil heavy metals.