波长色散X射线荧光光谱法快速测定大气 PM2.5中Cu和Zn的含量

摘要

介绍采用波长色散X射线荧光光谱法测定大气PM2.5中Cu和Zn含量的分析方法。采用聚四氟乙烯滤膜来制备标准样品和进行大气颗粒物采样；对大气颗粒物样品的装样杯结构进行了讨论，采用6.7μm的Polypropylene膜配合改进样杯来封装大气颗粒物样品，应用改进后的样杯对大气颗粒物中Cu和Zn进行测定，可明显降低背景，改善峰背比，降低检出限；讨论了大气PM2.5中目标元素Cu和Zn的测量条件，其分析线都采用 Kα线，分光晶体选用 PX10，采用间距300μm的准直器，Zn Kα线探测选用闪烁计数器， Cu Kα线的探测利用流气式正比计数器和封闭式正比计数器串联使用，工作电压、电流采用50 kV 和50 mA。应用制备的Cu和Zn标准样品建立工作曲线，实验结果表明，其线性相关性较好，准确度较高，Cu和Zn的相对标准偏差分别为2.43％和2.00％（n＝8），检出限分别为0.028和0.021μg · cm －2，且分析大气颗粒物单个样品时间为60 s。综上所述，该方法能够实现 PM2.5中Cu和Zn含量的快速、准确分析，为研究PM 2.5中的元素含量特征及来源解析提供科学依据。%This paper proposes the analyzing method of adopting wavelength dispersive X‐ray fluorescence spectrometry to meas‐ure the content of Cu and Zn in PM 2.5 .PT FE membrane is used to prepare standard samples and atmospheric particulate sam‐ples;a research into sample cup’s structure ,using polypropylene film of 6.7 μm to help to improved sample cup to package at‐mospheric particulate samples .The improved sample cup is used to measure the content of Cu and Zn in atmospheric particulate , which can obviously reduce background ,improve peak/background ratio and decrease detection limit to target element ;discus‐sion is made on the measurement condition of Cu and Zn in PM 2.5 :taking Kαline as analysis line of Cu and Zn ,selecting PX10 as analyzer crystal ,using 300 μm pitch collimator ,adopting scintillation detector for the Kαof Zn ,applying the integrating of flow‐gas proportional counter and closed‐end proportional counter to the Kαof Cu ,setting 50 kV ,50 mA as operating voltage and current .The prepared Cu and Zn standard sample is used to set up working curve ,the results show that their linear correla‐tions are better ,accuracy are higher ,relative standard deviations of Cu and Zn are 2.43% and 2.00% (n=8) ,detection limit are 0.028 and 0.021 μg · cm -2 respectively ,and analysis of the single sample only need 60 s .To sum up ,this method can quickly and accurately analyze the content of Cu and Zn in PM 2.5 ,and provide scientific basis for study the element content characteris‐tics and source apportionment .