【摘要】 能量色散X射线荧光光谱仪(EDXRF)的体积小、价格低,但测量土壤重金属含量的准确度和重复性较差。提出一种用于EDXRF的新型滤波准直器,设计了多档位滤光片以及可调啮合准直窗口,并验证了加装新型滤波准直器的EDXRF的测量重复性和准确性。结果表明,自制土壤样品测试中,加装滤波准直器后测得的Cr、Cu、Zn元素含量的标准差比安装前降低了50%以上;国家标准样品测试中,与加装滤波准直器前相比,加装后Cu、Zn、As、Pb、Cr、Hg元素含量的测量标准差分别降低了45.0%、42.8%、35.2%、23.1%、27.5%、91.7%,表明安装滤波准直器可以有效提升仪器测量的重复性;使用加装滤波准直器的EDXRF测定干燥土壤和含水率10%的土壤,发现降低含水率可以有效提升测量重复性。将自行设计的EDXRF与第三方检测机构的测试结果进行比较,发现二者测得的Pb、As、Cr、Zn、Cu元素含量基本一致或相差较小,说明自行设计的EDXRF对大部分元素含量具有较好的测量准确性。更多还原

【Abstract】 Energy dispersive X-ray fluorescence spectrometers(EDXRF) are small in size and low cost, but the accuracy and reproducibility of soil heavy metal content measurements are poor. A new type of filter collimator for EDXRF has been proposed in this work, and a multi-gear filter and an adjustable meshing collimating window have been designed. The reproducibility and accuracy of EDXRF measurements incorporating the new filter collimator have been verified. The results show that for measurements on self-made soil samples, the standard deviations of Cr, Cu, Zn element contents were reduced by more than 50% after installing the new filter collimator. For measurements on national standard samples, the standard deviations of Cu, Zn, As, Pb, Cr and Hg element contents were reduced by 45.0%, 42.8%, 35.2%, 23.1%, 27.5%, 91.7%, respectively, after installing the filter collimator. These results show that installation of the filter collimator can effectively improve the reproducibility of EDXRF measurements. When using EDXRF with the filter collimator to analyze soil samples with different moisture contents, it was found that reducing the moisture content can effectively improve measurement reproducibility. When the results for EDXRF with the filter collimator were compared with those of third-party testing agencies, it was found that the measured Pb, As, Cr, Zn, Cu element contents were almost identical or showed only small differences, indicating that EDXRF incoorporating the new filter collimator has high accuracy for most heavy metals commonly found in soil.更多还原