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针对传统能量色散X荧光仪(energy dispersive X-ray fluorescence,EDXRF)分析土壤中微量重金属测量精确度低的问题,提出了一种X荧光仪改进方法。为了减少反射X射线的影响,入射X射线垂直照射样品,探测器平行放置与样品一侧且垂直于X射线。样品与探测器之间由准直器连接。对国家标样测量结果表明,仪器对Mo,Zn,Cu,Pb,Zr,Nb的检出限为0.4,6.68,1.97,6.84,1.60,7.59mg·kg-1。各元素对数偏差在0~0.05之间。元素含量在三倍检出限以上RSD%(GBW)小于7,元素含量在三倍检出限内RSD%(GBW)小于15。为了验证改进后X荧光仪测量效果,在大兴安岭地区采集土壤样品与传统荧光仪进行比较分析。改进X荧光仪提高了土壤中微量重金属测量精度,满足野外地质普查要求。
Aiming at the problem of low accuracy of trace heavy metals measurement in soil by energy dispersive X-ray fluorescence (EDXRF) analysis, an improved method of X-ray fluorescence spectrometer was proposed. In order to reduce the influence of reflected X-rays, the incident X-rays irradiate the sample vertically, and the detectors are placed parallel to the sample and perpendicular to the X-rays. The sample and detector are connected by a collimator. The measurement results of the national standard samples showed that the detection limits of Mo, Zn, Cu, Pb, Zr and Nb were 0.4, 6.68, 1.97, 6.84, 1.60 and 7.59 mg · kg-1, respectively. The logarithmic deviation of each element is between 0 ~ 0.05. RSD% (GBW) above the triple detection limit is less than 7 for elemental content and less than 15 for RSD% (GBW) within three times the detection limit. In order to verify the improved X-ray fluorescence measurement results, soil samples collected in the Greater Khingan Range were compared with the traditional fluorometer. The improved X-ray fluorescence spectrometer improves the measurement precision of trace heavy metals in soil and meets the requirement of field geological survey.