能量色散X射线荧光光谱法测定自来水中痕量氯

采用能量色散X射线荧光光谱法,分别在空气、氮气和氦气气氛下测定自来水中痕量氯,结果表明,在氦气条件下不仅可以消除空气中氩气的干扰,还可以增加探测器接收到的氯谱峰强度,因此选择在氦气条件下采用能量色散X射线荧光光谱法测定自来水中痕量氯。通过研究氯元素峰背比与X光管管压、管流的关系,选择最佳工作条件为:光管管压15kV,光管电流800μA。氯质量浓度为0~200μg/mL时,与其对应的X射线荧光光谱相对强度呈线性,线性相关系数R²=0.9975;检出限为2.94μg/mL。按照实验方法测定30μg/mL和10μg/mL氯标准溶液中氯,结果的相对标准偏差(RSD,n=11)分别为11%和16%;对两个自来水实际样品进行加标回收试验,回收率为89%~119%。

Determination of trace chlorine in tap water by energydispersive X-ray fluorescence spectrometry

The content of trace chlorine in tap water was determined by energy dispersive X-ray fluorescence spectrometry in atmospheres of air, nitrogen and helium, respectively. The results showed that the helium atmosphere could not only eliminate the interference of argon in air, but also enhance the spectral peak intensity of chlorine received by detector. Therefore, the helium atmosphere was selected to determine trace chlorine in tap water by energy dispersive X-ray fluorescence spectrometry. The relationship between peak-to-background ratio and X-ray tube voltage and tube current was studied. The optimal working conditions were obtained as follows: the tube voltage was 15kV and the tube current was 800μA. When the mass fraction of chlorine was in range of 0-200μg/mL, it had linear relationship to the corresponding X-ray fluorescence relative intensity with linear correlation coefficient of R²=0.9975. The detection limit was 2.94μg/mL. The content of chlorine in standard solution (30μg/mL and 10μg/mL) was determined according to the experimental method. The relative standard deviation (RSD, n=11) was 11% and 16%, respectively. Two actual tap water samples were used for recovery tests. The spiked recoveries were between 89% and 119%.