[Background] The study of the detection limit of X-ray fluorescence instrument is of great significance, as it is widely used in the analysis of low content elements because of its excellent performance. [Purpose] To reduce the detection limit and measuring low content of metal elements more accurately, we provided reference for the choice of background subtraction methods and measurement conditions,etc. [Methods] This paper studied the influence factors for the detection limit of the portable X-ray fluorescence instrument, such as background subtraction method, tube voltage and tube current. Blank sample-, linear- and Sterlinski- background subtraction methods were used to subtract the backgrounds and the suitable tube voltage and tube current range were tested. Certain corresponding relationship exists between detection limit and determination limit, so the determination limit was obtained using the detection limit, and the low content samples were analyzed. [Results] Detection limit varies with tube voltage and tube current due to different background subtraction methods. The suitable tube voltage range of blank sample background subtraction is 28-40 kV and tube current range is 18-24mA, while that of linear background subtraction and Sterlinski background subtraction is 24-26 kV, 28-40 kV and 12-14 mA, 18-40 mA correspondingly. [Conclusion] Blank sample background subtraction is the best, followed by Sterlinski background subtraction, while linear background subtraction is not suitable for the low content element analysis. Each background subtraction method has its suitable tube voltage and tube current range.When the content of elements is equal to the detection limit, the signal of the element detected is reliable, but it can not be used in quantitative analysis.%讨论了便携式能量色散型X荧光仪检出限受背景扣除方法、管电压与管电流的影响.采用空白样扣本底法、线性本底扣除法、斯托林斯基法(Sterlinski)三种方法扣本底,试验了与之适宜的管电压与管电流范围,比较了三种方法的优缺点.检出限与测定限存在一定的对应关系,利用检出限得到测定限,对低含量的样品进行了定量的分析.为降低检出限值和更准确地测量低含量金属元素在背景扣除方法、测量条件等方面的选择提供参考.
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